11th protea hotel technopark, stellenbosch 8 - 10 march 2016 book 11t… · session 1: general...

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11th

SAPBA Symposium 2016

Protea Hotel Technopark, Stellenbosch

8 - 10 March 2016

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Table of Contents

General Information.................................................................................................... 2

List of sponsors .......................................................................................................... 4

Symposium Programme ............................................................................................. 7

List of poster presentations ...................................................................................... 13

Abstracts of keynote presentations .......................................................................... 18

Abstracts of oral presentations ................................................................................. 24

Abstracts of poster presentations ............................................................................. 62

List of delegates ....................................................................................................... 99

Index of Authors ..................................................................................................... 103

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General Information

Registration desk

The registration and information desk will be situated in Omega room for the duration of the meeting,

and will be open from Tuesday 8th (12:00 – 19:00), and Wednesday 9

th and Thursday 10

th March

(07:30 – 17:00).

Language

The official language of the symposium will be English. No simultaneous translation services will be

provided.

Oral presentations

All computer presentations must be checked for viruses and reach the registration desk at least one

session before your presentation, i.e. if you present the following morning you must submit by

tea/coffee break the previous day. Computer presentations must be in MS Office Power Point.

Please note that presenters will not be allowed to use their own computers. Oral presentations will be

limited to 15 minutes (12 minutes presentation, 3 minutes discussion).

Poster presentations

Posters will be displayed for the duration of the symposium in the Omega room. All the delegates

presenting a poster are kindly requested to put up their posters by no later than the first poster

session during the coffee break on Wednesday March 9th at taken down by the end of the coffee

break on Thursday March 10th. Posters should not exceed 1200 mm (length) x 850 mm (width). A

suitable adhesive will be supplied.

Name badges

All participants must wear their name badges at all times during the symposium. Badges should be

worn when attending the events on the social programme as well to ensure access.

Refreshments

Please note that all lunches and tea/coffee breaks will be served in the foyer of the conference centre.

Delegates who have indicated Halaal and/or Vegetarian needs during online registration have been

11th SAPBA Symposium General Information

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catered for during the cocktail, lunches and gala dinner. If you have any specialized dietary needs

please inform the symposium organizers. Delegates will be held responsible for any costs incurred

due to specialized dietary needs and/or items ordered from the hotel restaurant.

Smoking

The symposium venue is a non-smoking area.

E-mail and Wi-Fi access

No computers will be made available to delegates for reading e-mail and/or to access the internet.

Delegates will however have free Wi-Fi access (please note that the venue will enforce a fair usage

policy) at the conference venue. The password for access will be made available during the first

session.

Cellphones

Delegates are requested to switch all cellphones to silent during the symposium sessions.

Airport transfers

Delegates in need of an airport shuttle can contact Faizaan Arnolds who is the reservations agent at

the Protea Hotel ([email protected]) for assistance.

Social functions

The welcoming cocktail party will be hosted in the Omega room from 17:00 – 19:00 on March 8th.

Access to the cocktail party is included in the registration fee. On March 9th the symposium dinner

will be held at the historical Nooitgedacht wine estate (GPS Coordinates: S 33° 53.387′ E 018°

49.761′). The dinner will start at 19:00 in the garden with a welcome drink.

Symposium bags and booklets

No symposium booklets will be made available to delegates. Only a registration pack containing a

flash drive with the symposium booklet (electronic format), promotional material from sponsors, and

an extended symposium programme will be provided.

Refunds

No refunds.

mailto:[email protected])

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List of sponsors

The SAPBA like to extend their gratitude to all the above organizations for their valuable support:

Agri-Enviro Solutions (Exhibitor)

Harvest Master (Exhibitor)

Kinkaid (General sponsorship & exhibitor)

Lemnatech (Conference bags, Sponsorship towards keynote speaker & exhibitor)

Sensako (Sponsorship towards keynote speaker)

Spoor & Fisher (Sponsorship towards gala dinner & registration gift)

SRES & EFS (Exhibitor)

Stellenbosch University’s Plant Breeding Laboratory (Sponsorship towards keynote speakers &

workshop)

Wintersteiger (Exhibitor)

Zuern (General sponsorship & exhibitor)


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Symposium Programme

Tuesday, 8 March 2016

12:00 – 14:00 Secretariat open for registration

Opening session

Chair: Joseph Asiwe (UL)

14:00 – 14:15 Official welcome and opening

Willem C. Botes (SAPBA) & Danie Brink (Acting Dean, Faculty of

AgriSciences, SU)

14:15 – 15:00 K1: Sensor-based phenotyping technology facilitates science and breeding

Marcus Jansen (Lemnatec)

15:00 – 15:30 K2: Low-cost drones as agricultural scouts

James Paterson (Aerobotics)

15:30 – 16:00 Coffee/Tea break

16:00 – 16:15 O1: Rapid phenotyping and analysis of wood density in provenances of

Eucalyptus dunnii

A Nel

16:15 – 16:30 O2: Modernising stone-fruit breeding programmes at ARC Infruitec-

Nietvoorbij

C Hörstmann

16:30 – 16:45 O3: Simultaneous selection for multiple traits in sugarcane breeding

populations using logistic regression models

M Zhou

16:45 – 17:00 O4: Demand-led plant breeding approaches: implications for cultivar adoption

and commercialization in Africa

H Shimelis

17:00 – 19:00 Cocktail Function (Omega room)

11th SAPBA Symposium Symposium Programme

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Wednesday, 9 March 2016


Session 1: General breeding

Chair: Maryke Labuschagne (UFS)

08:30 – 09:00 K3: Global Partnership Initiative for Plant Breeding Capacity Building (GIPB):

The Crop Improvement Community of Practice

Chike Mba (Food and Agricultural Organization, Rome)

09:00 - 09:15 O5: Introduction of applied research and student training in the pear breeding

programme of the ARC

T Human

09:15 - 09:30 O6: Streamlining the ARC phase 2 pome fruit programme

M Soeker

09:30 - 09:45 O7: Phenotypic performance of exotic pigeonpea varieties in South Africa

J Asiwe

09:45 - 10:00 O8: Performance of new orange-fleshed sweet potato cultivars in South

Africa

S Laurie

10:00 - 10:30 Coffee/Tea break and poster viewing

10:30 - 10:45 O9: Mutations, secured by clonal propagation, can be detrimental to the

commercial sector in the absence of systematic phenotypic analysis

Z Bijzet

10:45 – 11:00 O10: Phenotypic data is an important component of a citrus breeding

programme

N Combrink

11:00 – 11:15 O11: Location and seasonal effects of genotypes reaction to Eldana

saccharina borer damage in sugarcane breeding in South Africa

M Lichakane

11:15 – 11:30 O12: Litchi breeding and cultivar development in South Africa: challenges

and future prospects

S Froneman


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11:30 – 11:45 O13: The use of polycross-nurseries in mango breeding

C Human

11:45 – 12:00 O14: Predicting sugarcane progeny chromosome numbers and DNA content

from parents using flow cytometry

L Mtshali

12:00 – 13:00 Lunch

13:00 – 14:00 Biannual General Meeting

Session 2: Quantitative Genetics

Chair: Hussein Shimmelis (UKZN)

14:00 - 14:30 K4: Data-driven selection strategies for conventional and genomic breeding

programmes

Geert Haesaert (University Ghent, Belgium)

14:30 - 14:45 O15: Five year growth performance and wood properties of Eucalyptus

grandis and Eucalyptus macarthurii hybrids in the summer rainfall regions of

South Africa and Swaziland

J Cele

14:45 – 15:00 O16: Prediction of breeding values using classical genetic evaluation and

genomic relationships in a Eucalyptus grandis population

MM Mphahlele

15:00 – 15:15 O17: Comparing family with individual genotype selection for sugarcane yield

and its components for the Midlands breeding programmes in South Africa

NW Mbuma

15:15 - 15:30 O18: Location and crop-year effects on sugarcane genotype performance in

the coastal short cycle breeding programmes for the KwaZulu-Natal coast

S Sengwayo

15:30 – 16:00 Coffee/Tea break and poster viewing


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16:00 - 16:15 O19: A statistical view on wheat yield improvement: its definition,

measurement and significance

M Booyse

16:15 - 16:30 O20: Combining ability, genetic gains and path coefficient analyses in a

maize inbred line population

I Mathew

16:30 - 16:45 O21: Analysis of the genetic diversity of the South African Black wattle

(Acacia mearnsii) breeding population using SSR markers

M.W. Bairu

16:45 - 17:00 O22: The influence of environment on some yield parameters of taro

(Colocasia esculenta)

W Jansen van Rensburg

19:00 - 22:00 Gala dinner (Nooitgedacht Estate)

Thursday, 10 March


Session 3: Crop quality

Chair: Willem Boshoff (PANNAR)

08:30 - 09:00 K5: Relationship between physicochemical properties of wheat flour proteins

and baking quality

Perry KW Ng (Michigan State University)

09:00 - 09:15 O23: Dough mixing characteristics measured by Mixsmart software as

possible predictors of bread making quality in three production regions of

South Africa

M Labuschagne

09:15 - 09:30 O24: Total tocochromanol concentration in white and whole wheat flour of

South African wheat cultivars

A van Biljon

09:30 - 09:45 O25: Multivariate statistical analysis of some bread quality traits for South

African commercial wheat cultivars

J Onsando


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09:45 - 10:00 O26: Heritability and expression of selected mixogram parameters in progeny

of parents varying for mixing time

FS Pelser

10:00 - 10:30 Coffee/Tea break and poster viewing

10:30 - 10:45 O27: Development of near-infrared models for prediction of wood and pulp

traits for the forestry industry

S Naidoo

10:45 - 11:00 O28: Characterisation of stone-fruit genotypes of the ARC breeding

programme in terms of carotenoid profiles and associated fruit quality traits

W Pieterse

11:00 - 11:15 O29: Molecular characterization of the ARC apple collection with respect to

the ACS1 gene involved in fruit ethylene production

KG Mhelembe

11:15 - 11:30 O30: Understanding apple russet: a molecular, genetic and metabolomic

viewpoint

J Lashbrooke

11:30 – 11:45 O31: Evaluation of genetic diversity within South African sugarcane breeding

populations and its implication on breeding

L Makome

11:45 – 12:00 O32: The status of South African plantation forestry gene conservation and

the development of a conservation strategy for the industry

A Kanzler

12:00 – 13:00 Lunch

13:00 – 14:00 SAPBA Executive Committee Meeting

Session 4: Disease resistance breeding

Chair: Reneé Prins (Cengen)

14:00 - 14:30 K6: Five critical concepts in breeding for rust resistance

ZA Pretorius (UFS)


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14:30 - 14:45 O33: Ten years of genotypic analysis of the three wheat rusts in Southern

Africa

B Visser

14:45 – 15:00 O34: Pathogenomics of South African stripe rust in a global context

HJ van Schalkwyk

15:00 – 15:15 O35: Improved genetic characterisation of the slow rusting stripe rust QTL

(QYr.sgi-4A.1) region of Kariega through SNP array analysis

C Smit

15:15 - 15:30 O36: Development of wheat lines with complex resistance to rusts and

Fusarium head blight

A Maré

15:30 – 16:00 Coffee/Tea break and poster viewing

16:00 – 16:15 O37: Multi-environment evaluation of maize inbred lines for resistance to

Fusarium ear rot and fumonisins

L Rose

16:15 – 16:30 O38: Standardizing sugarcane thrips (Fulmekiola serrata) damage,

identifying molecular markers, and its implication for resistance breeding

S Joshi

16:30 – 16:45 O39: Evaluation of cowpea varieties for bruchid (Callosobruchus

rhodensiansus) resistance in South Africa

IM Letsoalo

16:45 - 17:00 Concluding remarks and closing

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List of poster presentations

P1: Shortcutting cuttings

W Brink

P2: Molecular mapping of Fusarium head blight resistance genes in wheat

C Dweba

P3: Field performance of three generations of tepary bean mutants

ET Gwata

P4: Molecular characterisation of new sources of adult plant resistance to wheat rusts

S Figlan

P5: Impact of disease on forestry in the subtropical area of Zululand and future plans to monitor

the occurrence of new diseases

G Galloway

P6: Evaluations of mineral elements and total protein content in the immature pods of different

cowpea (Vigna unguiculata (L.) Walp.) genotypes in South Africa

A Gerrano

P7: An overview of the application of molecular markers at the Agricultural Research Council's

Institute for Tropical and Subtropical Crops

E Hajari

P8: Artificial screening for cold tolerance of various Pinus species and hybrids

H Ham

P9: Identification of crop wild relatives in South Africa

M Hamer

P10: Applications of flow cytometry in plant breeding programmes of the Agricultural Research

Council's Institute for Tropical and Subtropical Crops

K Hannweg

P11: Distant hybridisation as a breeding technique to improve papaya

J Husselman

P12: Unlocking the potential of crop wild relatives using predictive characterization

W Jansen van Rensburg

P13: Molecular fingerprinting and characterization of the ARC’s peach collections

L Kwalimba

P14: Combining ability of local and exotic maize (Zea mays L.) inbred lines for grain yield under

low nitrogen stress

P Makhumbila

11th SAPBA Symposium List of poster presentations

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P15: The effect of lower sodium chloride levels on bread quality

AF Malan

P16: Heritability and genetic gain for grain yield and path coefficient analysis of some agronomic

traits in early-maturing maize hybrids

S Maphumulo

P17: Identification of genes controlling dwarf trait in apple (Malus pumila Mill.)

Z Mbulawa

P18: Morphological diversity of selected South African sorghum (Sorghum bicolor L. Moench)

genotypes

A Mofokeng

P19: Improved resistance to Fusarium ear rot and fumonisin contamination in F1 maize hybrids

N Netshifhefhe

P20: Characterization of sweetpotato (Ipomoea batatas L. Lam) germplasm using morphological

traits and protein content

S Naidoo

P21: Evaluation of pod shattering in a distinct F2 plant population

KM Nevhudzholi

P22: Characterising South African historic wheat cultivars for seedling stem rust resistance

P Ntshakaza

P24: QTL validation of marker-trait associations for stem rust resistance in a diverse panel of

African wheat

R Prins

P25: DNA fingerprinting of fruit crops at the ARC

S Safodien

P26: Classification of ARC maize (Zea Mays L.) inbred lines into CIMMYT A and B heterotic pools

SF Shandu

P27: Mapping the Russian wheat aphid (Diuraphis noxia) resistance gene (Dn2401) on the 7DS

chromosome of wheat (Triticum aestivum L.)

T Sikhakhane

P28: Genetic analysis of stripe rust resistance in the wheat line NRSPan4

C Smit

P29: Optimal population size when pre-breeding for multiple pest resistance bread wheat lines

SL Sydenham

P30: Collection and preliminary characterization of the Spider plant (Cleome gynandra) germplasm

in Limpopo (South Africa).

F Thovhogi

P31: Pre-breeding bread wheat lines with Russian wheat aphid resistance

V Tolmay


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P32: Association of grain yield, proline and stress tolerance indexes in selection for drought stress

tolerance in soybean

R van der Merwe

P33: Yield potential and stability of vegetable-type soybean genotypes

R van der Merwe

P34: Guava breeding in South Africa: challenges and future prospects

S Willemse

P35: Protein fractions explaining the variation for Mixograph peak time in South African hard red

wheat cultivars

BS Wentzel

P36: Molecular characterization of Potato Virus Y strains in South Africa

LK Ledwaba

P38: Comparative differential gene expression analysis in response to PVY infection in resistant

and susceptible potato cultivars

M Ranketse

P39: Mapping quantitative trait loci for blush skin in European pear

S Ntladi

P40: MS-MARS facilitated pre-breeding aimed at the improvement of fungal resistance in wheat

SW Meintjes

P41: Initiation of a pre-breeding effort aimed at physiologically important traits for yield

improvement in wheat.

W Ngcamphalala

P42: Initiation of a pre-breeding effort aimed at water stress resistance traits for yield improvement

in wheat.

J Mthembu

P43: Initiation of a pre-breeding effort aimed at salinity resistance traits for yield improvement in

wheat.

N Cebekhulu


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Abstracts of keynote presentations

K1

Sensor-based phenotyping technology facilitates science and breeding

M. Jansen

Lemnatec, Germany

Grand challenges of the future, like feeding human population, dealing with climatic uncertainties,

environmental stress, or conserving biodiversity and natural resources, demand for substantial

improvements in plant breeding and crop management. Multi-level analysis of plant properties,

reaching from genome to phenome, is essential for making plant breeding, cultivation, and

management compatible to future scenarios. Substantial improvements in plant production and

adapting plants to novel uses in bio-materials, energy, and pharmaceuticals demand for rapid and

reliable characterisation of plant traits, in particular phenotypes. At the same time plant production

and management has to gain strongly in efficiency in order to deal with increasing limitations in

resource availability, and to minimise negative effects on natural ecosystems.

Phenotypic analysis takes place at laboratory-, greenhouse-, and field- scale and therefore demand

for platforms that carry sensor technology enabling non-invasive measurements. Such technology

delivers reliable, repeatable, and standardised datasets for plant science and breeding. Sensor fusion

makes data acquisition and evaluation comprehensive, but complex at the same time. Complex data

sets in turn enable mathematical models to describe and predict plant functionality and structure.

In particular field performance is of interest for researchers and breeders and therefore the novel Field

Scanalyzer was developed to assess phenotypes of plot-grown plants. The first installation runs at

Rothamsted Research in a joint project with LemnaTec. Other types of LemnaTec Scanalyzers

operate at laboratory and greenhouse level, and multiple scientific publications prove their utility in

plant growth analyses, mutant screenings, and stress assays. Moreover, several breeding and

agrochemical companies rely on such technology for candidate genotype test or substance screening.

Such applications not only comprise plant phenotyping as such, but also image analysis for

measuring insect or microbe responses. Recent developments enable seed- and germination-

screening. Root phenotyping for soil-grown and agar-plate-grown plants is in focus of current

developments.

11th SAPBA Symposium Keynote presentations

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K2

Low-cost drones as agricultural scouts

J. Paterson

Aerobotics

The use of drones in agriculture allows for the collection of imagery and sensor data over large areas

in a short period of time. Data collected from drones can be used to generate high-resolution maps,

monitor crop health, height, irrigation stress, as well as aid in yield estimation.

Aerobotics is leveraging recent advancements in guidance systems, batteries and low-cost sensors to

make this drone technology practical and affordable for every farmer. This talk gives an overview of

drone types, sensor types, methods used to generate actionable data from collected images and

some of the challenges faced with this technology.

K3

Global Partnership Initiative for Plant Breeding Capacity Building (GIPB): The Crop

Improvement Community of Practice

C. Mba

Seeds and Plant Genetic Resources Team, Plant Production and Protection Division, Food and

Agriculture Organization of the United Nations, Rome, Italy

Significantly more nutritious food must be produced, without further damaging the environment and/or

human health, in order to feed an ever-growing population in the face of climate change. In fact, the

global food and agricultural research and development community is grappling with devising the

means for producing an unprecedented 60 to 70 percent more food in the coming four decades

without recourse to additional arable lands, agricultural water resources and external inputs.

Undoubtedly, farmers must have access to a diverse suite of well-adapted, nutritious and input use-

efficient crop varieties in order to attain this lofty goal sustainably. For farmers to have access to these

‘smart’ crop varieties, a critical mass of skilled plant breeders and ancillary scientists must be

available to apply both classical and powerful novel tools to generate superior crop varieties capable

of translating the potentials encoded in the genetic blueprints of plant genetic resources for food and

agriculture into improved productivities on farmers’ fields. Evidence abounds that the numbers of


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these skilled personnel available in the public sector breeding programs, which are mandated with

several food security crops of many developing countries, are sub-optimal. It was in a bid to redress

this that the multi-stakeholder platform, the Global Partnership Initiative for Plant Breeding Capacity

Building (GIPB), was convened by the Food and Agriculture Organization of the United Nations and

multiple development partners. We describe GIPB’s successes in the developments of policy and

advocacy instruments; enhancing human and institutional capacities; facilitating access to

technologies; fostering the exchange of PGRFA; and disseminating information. . We also describe

the e-learning course on pre-breeding which was developed under GIPB’s auspices as means to

facilitate the further broadening of the genetic base of parents used in plant breeding. We also provide

an overview of the customizable Planning and Assessment Tool which will aid policy makers and

development agencies in assessing the fitness for purpose of need-based crop improvement

programs. Finally, we offer perspectives on the ideal profile of the plant breeding team in a demand-

driven program.

K4

Data-driven selection strategies for convential and genomic breeding programmess

G. Haesaert 2, Maenhout, Steven

1,2 and Bernard De Baets

1

1Department of Mathematical Modelling, Statistics and Bioinformatics, University Ghent

2Department of Applied Biosciences, University Ghent

As the price tag of high-density genotyping comes down, genomic selection gradually finds its way

into breeding programs of various plant and animal species. Widespread adoption of this selection

approach is, however, hindered by a lack of user-friendly software that allows practical breeders to

distil reliable breeding values from their available phenotypic and genotypic data collections. The

increasing density of commercial SNP chips and the computational challenges this imposes on

existing software solutions forms a second hurdle which is generally difficult to overcome without

considerable concessions with respect to the dimensionality of the initial problem.

These two obstacles have been the key motivation for the development of the Progeno software

system. In its core, Progeno is a linear mixed model computing engine which was written from scratch

to solve problems involving millions of unbalanced phenotypic observations in combination with dense

molecular marker profiles containing tens, if not hundreds of thousands of individual marker scores. It

offers ample model flexibility including a wide range of possibilities for imposing a predefined structure

on the variance of random effects and residuals including unstructured, compound symmetry,


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autoregressive, anisotropic and many other variance and correlation structures. Pedigree and

molecular marker information can be integrated in the variance structure of random effects using

various approaches ranging from a classic numerator relationship matrix to more recent advances

such as Reproducing Kernel Hilbert Space Regression. Unknown variance parameters are estimated

from the data by means of Average Information Restricted Maximum Likelihood. The computational

workload can be spread over multiple processors and flexible out-of-core storage techniques avoid

having to compromise with respect to data quantity or model complexity due to computer memory

limitations.

The Progeno computing engine allows to integrate all the available phenotypic and molecular data

that has been gathered over many years of breeding. For each phenotypic trial, the linear mixed

model formulation that produces the best fit to the data is automatically selected using a subset of a

predefined selection of candidate model terms and residual variance structures. The specific model

details of each trial are combined in an all-encompassing meta model after which all variance

parameters are re-estimated producing the optimal model for the available data. Outlier detection and

cross-validation routines allow to identify suspicious observations and validate the quality of the

resulting model respectively.

The resulting prediction models can be valorised by breeders by means of an user-friendly web

application that allows to explore raw, corrected and aggregated trial results and to obtain breeding

values for individuals with phenotypic observations as well as pedigree- or genomic-based predictions

for unobserved and non-existent individuals or crosses. The system also generates optimal cross-

advice when provided with a set of candidate parental individuals and a weighing of the relative

importance of each trait.

The industrial applicability of the presented Progeno technology has been validated in commercial

breeding programmes of maize, winter oilseed rape, potatoes, pigs and orchids and proof-of-concept

projects for various other species are ongoing.


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K5

Relationship between Physicochemical Properties of Wheat Flour Proteins and Baking Quality

P.K.W. Ng

Department of Food Science and Human Nutrition, Michigan State University

Wheat flour proteins are unique and the largest protein molecules found in nature. The uniqueness of

these polymers provides a wide array of opportunities to the food industry to produce high quality

products in which no other natural polymer materials can be substituted. Wheat flour protein

chemistry and the roles flour proteins play in dough rheology will be briefly reviewed. Results will be

presented from a few studies to illustrate novel approaches to understanding the relationship between

wheat flour proteins and dough rheology and the opportunities for the food industry for producing

innovative products.

K6

Five critical concepts in breeding for rust resistance

Z.A. Pretorius

University of the Free State, Bloemfontein

Rust diseases continue to cause significant yield losses in numerous crops of economic importance.

Current day threats include the rusts of barley, coffee, common bean, lentil, maize, oat, ornamental

plants, soybean, sugarcane, sunflower, tree species, wheat, etc. The fungal organisms which cause

rust diseases are diverse but in general are adapted to rapid dispersal and build-up of inoculum,

some have complex life cycles with alternate and ancillary hosts, whereas sophisticated parasitism

and inherent genetic variability contribute to their successful nature. Breeding programmes aimed at

rust resistance require dedicated and detailed attention to several areas of research. These concepts

will be dealt with in the presentation.

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Abstracts of oral presentations

O1

Rapid phenotyping and analysis of wood density in provenances of Eucalyptus dunnii

A. Nel , W. Naidoo, T. Le Roux and A. Kanzler

Sappi Forests Research, Planning and Nurseries, P.O. Box 1314, Howick, 3290, South Africa

During the past decade, Eucalyptus dunnii, Dunn’s white gum, has increased in importance as a

commercial South African forestry species. Favourable properties such as drought and cold tolerance,

adaptability and tolerance to some pests and diseases make it highly desirable to the South African

forestry industry. E. dunnii occurs naturally in two distinct populations in a restricted area in the border

region between New South Wales and Queensland in Australia, and these natural populations are

well represented in the breeding populations in South Africa. Previous growth studies have indicated

that limited variation in growth properties exist in these populations. Results from this study confirmed

the low provenance variation in growth properties, but found significant provenance and family

variation for wood density traits. Wood density is an important property for pulpwood, and is an

important economical factor in the production process. There were significant family (p=0.0005) and

provenance (p=0.0247) effects for wood density determined with increment wood cores, and

provenances from the two distinct natural populations grouped together. Individual tree heritability for

wood density was 0.43, compared with 0.10 for diameter growth. This information can be used to

structure the breeding programme into sub-populations based on wood density. The genetic analysis

of wood density determined with traditional increment wood cores was also compared with that using

a rapid phenotyping technique using a Resistograph® increment drill.

11th SAPBA Symposium Oral presentations

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O2

Modernising Stone-fruit Breeding Programmes at ARC Infruitec-Nietvoorbij

C.U. Hörstmann and K. Tobutt

Cultivar Development Division, ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599,

South Africa

For nearly eighty years the ARC and its various preceding institutions have been running stone-fruit

breeding programmes. During the 2013/2014 season ARC bred cultivars accounted for almost 65% of

the approximate 8640 hectares of peaches, plums and apricots planted in South Africa. However the

industry faces significant challenges. The plum breeding programme has released many excellent

cultivars over the last half decade, in contrast the total apricot acreage has been shrinking steadily at

about 140 ha/annum since 2009, one of the main reasons being a lack of good replacement cultivars.

The ARC is struggling to meet the requirements of apricot markets, and the breeding programme is

under pressure to rush evaluation and release cultivars. The challenge is to build on the successes of

the past and not rely on them. With the modern age come modern technology that can be applied to

breeding programmes. The modern breeder also has to contend with modern challenges such as

restricted funding, competition from foreign breeding programmes, tightly controlled quarantine

structures that hinder the import of new germplasm, and the high demands for fast outputs from

industry in a development field that takes place in terms of decades. Modern technology can however

speed up breeding to a certain extent. By applying molecular markers to fingerprint and characterise

known function genes in ARC genebanks and selections the programmes can design better crosses,

and screen seedlings before going to field, saving on costs and time spent evaluating less than

optimal material. Tissue culture also allows for germplasm to pass though quarantine much more

easily, but comes at higher financial cost. It is in this environment that the traditional stone-fruit

breeding programmes at ARC Infruitec-Nietvoorbij need to change to meet the challenges, embrace

the opportunities, and deliver top quality cultivars to the South African market.


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O3

Simultaneous selection for multiple traits in sugarcane breeding populations using logistic

regression models

M. Zhou

South African Sugarcane Research Institute (SASRI), Private Bag X02, Mount Edgecombe, 4300

Simultaneous selection for multiple traits in plant breeding is known to increase the value of varieties

to growers because a cultivar is required to possess optimum high trait values for several

economically important characteristics. Visual selection is inefficient while multivariate statistical

analysis is too complicated for large data sets. Nearest neighbour analysis and partial replication are

limited to analysing one trait at a time. The objective of this study was to demonstrate logistic

regression models as a statistical tool for simultaneous selection of several traits in sugarcane

breeding. The data for stalk number, height and diameter, sucrose and fibre content and number of

Eldana saccharina Walker (Lepidoptera) bored stalks collected from Stage II trials at Bruyns Hill

(BSL13) and Glenside (SSL13) research stations in the Midlands Region of KwaZulu-Natal, were

analysed using the logistic procedure of SAS. Stalk numbers, height, diameter and number of eldana

bored stalks were highly significant (P<0.0001) indicating their value in simultaneous selection for

high cane yield. Sucrose and fibre content were non-significant indicating the need to increase their

genetic diversity in these breeding populations. Selected genotypes in BSL13 populations produced

20% more stalks that were 23% taller and 7% thicker while those for SSL13 had 22% more stalks that

were 21% taller and 10% thicker. The selected genotypes produced 66% higher cane yield for BSL13

and 74% higher cane yield for SSL13. Eldana damage in selected genotypes was 37% lower for

SSL13 and 14% lower for BSL13. Simultaneous selection for high stalk numbers, taller and thicker

stalks with lower eldana damage achieved higher cane yield. The logistic regression models can be

applied for simultaneous selection for several traits in stage I to identify superior families, and in

replicated stages to select genotypes with optimum combination of important commercial

characteristics for release.


27

O4

Demand-led plant breeding approaches: implications for cultivar adoption and

commercialisation in Africa

H. Shimelis 1, P. Tongoona

2, P. Kimani

3, N. Yao

4, R. Chirwa

5, J.C. Rubyogo

6, V. Anthony

7 and G.

Persley8

1School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag

X01, Scottsville 3209, Pietermaritzburg, South Africa

2West Africa Centre for Crop Improvement, College of Basic and Applied Sciences, University of

Ghana, Legon, PMB LG 30, Ghana

3Plant Breeding and Biotechnology Program, Department of Plant Science and Crop Protection,

College of Agriculture and Veterinary Sciences, University of Nairobi, P.O Box 29053-00625 Nairobi,

Kenya

4Biosciences for Eastern and Central Africa (BecA), International Livestock Research Institute, P. O.

Box 30709, Nairobi 00100, Kenya

5Chitedze Agricultural Research Station, P.O. Box 158, Lilongwe, Malawi

6Seed Systems and Agr. Technology Transfer, CIAT-Tanzania

7Syngenta Foundation for Sustainable Agriculture, WRO 1020.11.66, Schwarzwaldallee 215, P.O.

Box, CH‐4002, Switzerland

8Gabrielle Persley, Global Change Institute, University of Queensland, St Lucia, Australia

There is low adoption of improved varieties in Africa estimated at <35% compared to >60% in Asia

and >80% in South America. The reason for the low adoption in Africa is attributed to, among other

factors, limited consultation of stakeholders such as farmers, processors, retailers and consumers in

the crop value chain by breeders during variety development. Adoption of newly bred varieties can be

improved by the involvement of clients in the design, development and commercialization of crop

varieties. This paper presents the contents of a Demand-led Plant Breeding Module which describes

the principles and processes of stakeholder consultation during cultivar design and development. The

module comprises of seven units as follows: Unit 1 - Principles of Demand-Led Plant Variety Design;

Unit 2 - Visioning and Foresight for Setting Breeding Goals; Unit 3 - Understanding Clients’ Needs;

Unit 4 - Variety Design and Setting Standards; Unit 5 - Variety Development Strategy, Stage Plan,

Timelines and Variety Registration; Unit 6 - Investment Decisions in Variety Development and Unit 7 –

Monitoring, Evaluation and Learning (MEL). The demand‐led module was developed by a partnership

among plant breeding education and research institutions in Africa, the Syngenta Foundation for

Sustainable Agriculture, the Crawford Fund, the Australian International Food Security Research

Centre and the Global Change Institute of the University of Queensland. The target audiences for the


28

Demand-led Plant Breeding Module are postgraduate plant breeding students, educators,

professional breeders and R&D managers. Inclusion of the demand-led breeding approach in plant

breeding curricula in Africa may promote improved variety adoption.

O5

Introduction of applied research and student training in the pear breeding programme of the

ARC

T. Human


South Africa

One of the major breeding objectives of the ARC pear (Pyrus communis L.) breeding programme in

South Africa is breeding a range of blush cultivars. Blush pears are still regarded as novel and fetch a

price premium over normal green, yellow or brown cultivars on overseas markets. Early successes of

the ARC in breeding blush cultivars such as ‘Rosemary’ and ‘Flamingo’ and, more recently,

‘Cheeky®’, created an opportunity for South African pear producers to capitalise on the high prices.

Conventional pear breeding is time-consuming and expensive, with a minimum time lapse of 18 years

from crossing to cultivar release, and breeders are constantly looking to stream-line the process. The

tools of marker-assisted selection (MAS) should definitely contribute to breeders’ efforts in this regard,

but unfortunately few markers are available to pear breeders. Therefore, there is a need to identify

microsatellite markers which are linked to genes / alleles associated with economically important traits

and disease resistance to allow MAS at a very early stage of seedling development. Thus, as part of

the mission of the ARC to develop the next generation of breeders and geneticists, students are being

trained to perform such applied research as part of their MSc or PhD studies, currently in

collaboration with Stellenbosch University (SU). Progenies have been raised which are segregating

for attributes like lower chill requirement, blush skin, full red colour, good flavour, susceptibility to

internal breakdown and double flowers. This presentation will explain the parallel methods of

conventional and molecular assisted breeding whilst highlighting the involvement of students and

other achievements of the breeding programme.


29

O6

Streamlining the Agricultural Research Council’s (ARC) Phase 2 Pome Fruit Programme

M.K. Soeker

ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599

The fruit breeding programme at ARC Infruitec-Nietvoorbij deals with many different fruit crops, of

which pome-fruit (apple and pear), stone-fruit and grape are the most important. In recent years,

pome-fruit breeding and evaluation have been left behind. This has partly been due to lack of

manpower and resources, as well the complexity of the fruit species. The addition of the pome-fruit

evaluator in 2012, to the breeding team at the ARC has allowed a rethink of the Phase 2 evaluation

programme. This has resulted in more stringent evaluation, better record keeping (new databases),

earlier industry involvement and a greater collaboration, with other divisions at the institute, viz. Post-

Harvest and Biometry Divisions. In addition, the availability of THRIP funding has allowed the

implementation of molecular techniques in the Phase 2 programme. The use of SSR markers to

fingerprint the ARC’s advanced selections is now well advanced, allowing us to check trueness-to-

type, as well as to guard against mishaps in the orchards; and it will also facilitate IP protection to

guard the ARC’s selections against unauthorised propagation. We have also been able to place

greater emphasis on the characterization of these advanced selections with gene-based markers for

genes involved in ripening (ACS1) and incompatibility (S-alleles). In future, we hope to apply some of

these markers earlier in the programme to screen selections for promising traits and removing non-

promising selections before they are planted in the orchard and thus save time and money.


30

O7

Phenotypic performance of exotic pigeonpea varieties in South Africa

J.A.N. Asiwe

University of Limpopo (Turfloop Campus), Department of Plant Production, Soil Science and

Agricultural engineering, Private Bag X1106, Sovenga, 0727 South Africa

Pigeon pea (Cajanus cajan (L.)) is an important tropical grain legumes with world average yield of 684

kg/ha. Pigeonpea is an important source of cheap plant protein, feed for animals, fuel or fire wood for

rural dwellers, green manure and biological plough for nutrient recycling. The yield of pigeonpea in

South Africa is very low because cultivars grown by farmers are long duration types and

photosensitive. The introduction of early maturity types are critically important for sustainable

pigeonpea production in Limpopo province.

Twenty two varieties introduced from ICRISAT Kenya were evaluated at the University Research

Farm. The trials were laid in a randomized complete block design with three replications. During crop

growth, the trial was protected from weeds and insects, and data were collected on plant height, days

to 50% flowering, number of pods per plant, days to 75% maturity and grain yield.

The results show that significant difference (P< 0.05) was observed among the varieties for all the

variables measured. Among the 22 varieties, nine varieties (ICEAP 00604, ICEAP 00612, ICEAP

00652-2, ICEAP 01101-1, ICEAP 01101-2, ICEAP 01106-1, ICEAP 01107-5, ICEAP 01107-6, and

ICEAP 01107) flowered early with a range between 89 and 95 days to attain 50% flowering. Grain

yield varied from 951 to 5371 kg/ha with variety ICEAP 00659 exhibiting the highest yield while ICEAP

01101-1 was the poorest (951Kg/ha).

Five early flowering varieties (ICEAP 00604, ICEAP 01101-2, ICEAP 01107-5 and ICEAP 01284) are

recommended for cultivation in Limpopo province, as well breeding stock for the improvement of

pigeonpea varieties in South Africa.


31

O8

Performance of New Orange-Fleshed Sweet potato Cultivars in South Africa

S. Laurie , W. Mphela, R. Greyling and P. Adebola

Agricultural Research Council, Roodeplaat, Vegetable and Ornamental Plant Institute, Private Bag

X293, Pretoria, 0001

South Africa has a diverse population, with some pockets of society being in a first world setup and

other in third world impoverished setup; furthermore vitamin A deficiency is a serious health problem.

One strategy to combat micronutrient deficiency is through biofortification, particularly orange-fleshed

sweet potato [Ipomoea batatas (L.) Lam] is promoted for this purpose due to high content of naturally

bio-available β-carotene. Availability of cultivars with high dry mass, good yield, and good taste is

critical in this regard. Local cream-fleshed parents and orange-fleshed US introductions were used in

the local polycross program. In the present study agronomic performance, stability, and genetic

diversity of newly developed orange-fleshed genotypes were tested. Twelve entries were evaluated at

four sites for two seasons in multi-environment trials and the data was subjected to ANOVA and

genotype plus genotype-by-environment interaction (GGE) biplot analysis. Simple-sequence repeat

(SSR) analysis of the 12 entries was done followed by hierarchical clustering. Cultivar Impilo

produced stable, high root yield similar to the commercial control cultivar Beauregard. The genetic

analysis indicated relatedness of most new genotypes with the cream-fleshed parents used in the

polycross program. The improved cultivars offer considerable yield advantage above US introductions

previously recommended for combating vitamin A deficiency. During the past year, over 1 million

cuttings of improved orange-fleshed sweet potato were disseminated to six of the SA provinces and

planted by small-scale commercial farmers for income generation. In order to exploit the nutritional

benefits of orange-fleshed sweet potato, private–public partnerships and investment will be needed

for upscaling the impact of new cultivars on food and nutrition security.


32

O9

Mutations, secured by clonal propagation, can be detrimental to the commercial sector in the

absence of systematic phenotypic analysis

Z. Bijzet , J.H. Husselman and I.J. Froneman

Agricultural Research Council, Institute for Tropical and Subtropical Crops, Private Bag X11208,

Nelspruit, 1200, South Africa

Plant breeding has been defined as the art and science of changing the traits of plants in order to

produce desired characteristics and this can be achieved in various ways from simply selecting plants

with desirable characteristics for propagation, to more complex molecular techniques.

One of these techniques is the use of natural occurring and induced mutations especially when the

aim is to improve one or two easily identifiable characters in an otherwise well-adapted cultivar. The

main advantages are that the basic genotype of the variety is usually only slightly altered, while the

improved characters are added, and that the time required to breed the improved variety can be

shorter than when hybridisation is used to achieve the same result.

In crops where a highly sought after enhanced trait can be secured through vegetative propagation,

the benefit of mutations (spontaneous or induced) is even more profound especially in view of a

constantly growing need for new and innovative cultivars to meet the changing requirements of the

markets, and optimize accessibility of cultivars to Southern African producers.

Although a mutation is a one-cell event, multicellular apices generally consist of a number of cell

layers such as the epidermis, sub-epidermis and the rest and have a number of meristematic cells in

each layer. More than one vegetative cycle is therefore needed to confirm the stability of a new

attribute. The consequences of premature registering and commercialising of a mutated cultivar could

be detrimental to the commercial sector. Case studies are presented to illustrate the impact of fast

tracking mutations into the commercial domain without a systematic phenotypic analysis approach


33

O10

PHENOTYPIC DATA IS AN IMPORTANT COMPONENT OF A CITRUS BREEDING PROGRAMME

N. Combrink1 , Z. Bijzet

2, M. Booyse

3 and M. Labuschagne

4

1ARC-Institute for Tropical and Subtropical crops, P.O. Box 25, Addo, 6105

2ARC-Institute for Tropical and Subtropical crops, Private Bag X11208, Nelspruit, 1200, South Africa

3ARC-Biometry, Stellenbosch, P.O. Box 3279, Matieland, 7602

4University of the Free State, P.O. Box 339, Bloemfontein, 9300

Conventional citrus breeding programmes generally aim at improving several different characteristics,

each with a different inheritance pattern. This complicates the process of parent selection and the

planning of controlled crosses. Information on the interrelationships among fruit characteristics is very

important as the probability of breeding a new superior quality cultivar depends largely on these

relationships. An understanding of the inheritance of these characteristics can aid in the selection of

parents and planning of controlled crosses. Phenotypic data was collected from six mandarin families,

with ‘Kiyomi’ as female parent and ‘Dancy’, ‘Hansen’, ‘Rishon’, ‘Roma’, ‘Shani’ and ‘Sunburst’ as male

parents, for the characteristics of rind colour, fruit size, fruit shape, Brix %, acid percentage and the

Brix to Acid ratio. This data was collected in order to gain information on the interrelationships among

the fruit characteristics studied as well as how they are inherited.

Female parent ‘Kiyomi’ was very different from the male parents, while a small variation was found

between the families. All the families showed an improvement in the population over one of the

parents for rind colour, fruit size and fruit shape. The ‘Kiyomi’ x ‘Rishon’ family was superior for the

Brix:acid ratio, while the other families inherited a high acid. The fruit’s external quality characteristics,

of rind colour, fruit size and fruit shape, were inter-correlated while the internal fruit characteristics of

acid percentage and the Brix:acid ratio were correlated. There were no correlations between the fruit’s

external quality characteristics and the fruit’s internal quality characteristics. Therefore, fruit

characteristics contributing to different traits were mostly independent from each other and it is

possible to improve traits such as rind colour, fruit size, fruit shape and the fruits internal quality

through breeding in citrus.


34

O11

LOCATION AND SEASONAL EFFECTS ON GENOTYPES REACTION TO ELDANA

SACCHARINA BORER DAMAGE IN SUGARCANE BREEDING IN SOUTH AFRICA

M. Lichakane1 and M. Zhou

1,2

1South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, KwaZulu-Natal,

4300

2University of the Free State, P.O. Box 339, Bloemfontein, 9300, Free State, South Africa.

Eldana saccharina (eldana) is a stem borer of sugarcane that causes yield loss by tunnelling through

the sugarcane stem. Losses attributed to eldana are more than R744 million per annum. The

objective of this study was to evaluate the influence of genotype by environment interaction (GxE) on

the eldana damage and implications for resistance breeding Data were collected from trials planted at

five locations, from 2003 to 2007 and harvested in plant, first and second ratoon crops. Twenty stalks

per plot were randomly chosen, number of bored stalks counted and converted to percent (PBS).

There were highly significant (p<0.001) location effects indicating differences in levels of damage

indicating that some locations might be more suitable as screening sites compared to others. Three

Gingindlovu locations had high PBS ranging from 48.52 to 69.87 % which was significantly higher

than the two Kearsney locations with 13.87 to 36.08 %, suggesting Gingindlovu is an ideal screening

site. Highly significant (p<0.001) genotype effects were observed, showing differences in the levels of

damage and the ability to discriminate among genotypes. Location by genotype (GxL) effects were

highly significant (p<0.001) indicating damage among genotypes was significantly influenced by

location. This implies the ability to discriminate for location specific eldana resistance. There were

significant (p<0.05) genotype by crop (GxC) interaction effects in 2003, 2005 and 2006, indicating

seasonal effects. The trials were grown during drought seasons which significantly increased eldana

damage from 53.00% with normal rainfall to 95.78 % during drought. Location by genotype by crop

interaction (GxLxC) was significant (p<0.05) for 2003, 2004 and 2006 indicating presence of complex

GxE for eldana resistance.


35

O12

Litchi Breeding and Cultivar Development in South Africa: challenges and future prospects

A. D. Sippel1, J.H. Husselman

2 and I.J. Froneman

1,

1ARC-Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa

2ARC-Institute for Tropical and Subtropical Crops, P.O. Box 25, Addo, 6105; South Africa

For more than a century, only two cultivars have dominated litchi plantings in South Africa, with

‘Mauritius’ at 75% and ‘McLean’s Red’ at 25%. Due to increasing competition from other Southern

Hemisphere producing countries a demand arose for high quality early and late cultivars. A project

was thus initiated in 1992 by researchers of the Agricultural Research Council’s Institute for Tropical

and Subtropical Crops (ARC-ITSC) where available germplasm, mainly limited to research orchards,

were evaluated in a coordinated manner. This was followed with a breeding project to purposefully

combine favourable traits of promising material through hybridization. These initial efforts in litchi plant

improvement were hampered by a lack of genetic diversity in the local collection, necessitating the

enlargement of the narrow genetic base of cultivars available in South Africa. This led to a focused

collaboration effort with researchers and producers of other litchi producing countries to obtain

advanced cultivars and breeding lines from these sources. Subsequently a total of 34 new cultivars

and/or selections were imported and added to the local germplasm collection. The addition of these

new cultivars/selections to the breeding programme will substantially increase the probability of

producing outstanding new strains in years to come. Additionally, a genotype reference database for

litchis was recently created at the ARC-ITSC, using molecular marker technology. The database will

serve to facilitate the characterization of litchi cultivars and the establishment of a core collection of

cultivars for more focused breeding. This presentation focusses on recent advances in local breeding

efforts and techniques, as well as progress with the establishment and multiplication of newly

imported litchi and longan cultivars in South Africa.


36

O13

The use of polycross-nurseries in Mango breeding

C. Human , S. Willemse and A. Sippel

Agricultural Research Council - Institute for Tropical and Subtropical Crops, Private Bag X11208,


The mango industry in South Africa is mainly based on five or six commercial cultivars with numerous

negative characteristics, therefore the mango breeding program of the Agricultural Research

Council’s Institute for Tropical and Subtropical Crops (ARC-ITSC) was started during 1990. Although

the classical breeding of mango cultivars is an inefficient and time consuming process, most of the

current mango cultivars were derived from classical breeding or random selection. Natural crosses

(open pollination) are mainly used in the ARC-ITSC breeding program although artificial crosses

(hand pollination) and caging of topworked cultivars were also used. Due to the low success rate of

hand pollinations, open pollinated crosses from polycross-nurseries are used. Polycross nurseries

involve planting selected parent clones in an isolated area with the plants positioned in a manner that

facilitates all possible combinations. A second phase statistical trial with 11 promising selections

compared to four commercial cultivars also doubled up as the polycross-nursery. Crossing is by way

of natural pollinators and while the female plant is known the pollen source is not. The progeny are

evaluated in different orchards to determine their commercial potential. In the Phase I phase open

pollinated seedlings are planted in high density orchards. The aim is to establish 500-1000 trees per

year. This seedling program consisted of 2696 seedlings spread over six hectares. Currently 330

(12.2%) of the seedlings originated from the polycross-nursery. A total of 91 selections were made

from the seedlings that originated from the polycross nursery. This high percentage of promising

selections can be attributed to the concentration of beneficial genes in the polycross nursery.


37

O14

PREDICTING SUGARCANE PROGENY CHROMOSOME NUMBERS AND DNA CONTENT FROM

PARENTS USING FLOW CYTOMETRY

L. Mtshali1 , M. Zhou

1,2, M. Labuschagne

2 and J. Albertyn

2

1South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, Durban,

South Africa

2University of the Free State, P.O. Box 339, Bloemfontein, 9300, Free State, South Africa.

Sugarcane cultivation, milling and sugar refining in South Africa is a R12 billion industry and relies

heavily on releasing superior varieties. Investing in sugarcane improvement increases cultivar genetic

gains. Knowledge of sugarcane cytogenetics will improve the efficiency of commercial and

introgression breeding and their ability to deliver cultivars and parental genotypes. Flow cytometry is

used to determine genomic size and DNA ploidy in plant cytogenetics. This study aimed to estimate

and compare the DNA content, chromosome numbers and DNA ploidy of sugarcane genotypes and

predict progeny DNA content and chromosome numbers. DNA content and ploidy of genotypes from

six commercial and four introgression crosses was determined using maize as a standard and the

data analysed using the Statistical Analysis System (SAS). The low coefficient of variation (CV% <

1.5%) and R² > 0.95 indicated repeatable data. There were highly significant differences (P < 0.001)

between commercial and introgression parents and progenies. Introgression parental genotypes

produced 9.2% higher DNA content, 9.6% more chromosomes and 9.6% higher DNA ploidy than

commercial genotypes. Introgression parents also produced higher standard deviations in DNA

content (36.1%), chromosome numbers (35.97%) and DNA ploidy (35.61%) estimates than

commercial parents indicating higher population variability. Highly significant (P < 0.001) and positive

(> 0.9) correlations were present between the DNA content estimates, chromosome numbers and

ploidy levels. Multiple linear regression analysis showed that male parents were significantly

associated with a 0.42 (P=0.0026) increase in DNA and 0.45 (P=0.0004) increase in chromosome

numbers of progenies. The significant association indicates that special focus on males during parent

selection is required. Female parents had a non-significant association with both DNA (0.19,

P=0.4203) and chromosome numbers (0.23, P=0.2299) of progenies. Predicting DNA and

chromosome numbers of progenies from parental genotypes could be used to determine progeny

genetics and performance during crossing.


38

O15

Five year growth performance and wood properties of Eucalyptus grandis and Eucalyptus

macarthurii hybrids in the summer rainfall regions of South Africa and Swaziland

J. Cele and T. Swain

Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, 3209.

Global predictions for the next 50-100 years foresee an increase in temperature, increase or decrease

in rainfall, and increase in frequency and intensity of extreme events. Therefore the development of

Eucalypt hybrids that can tolerate these events is a priority. Eucalyptus grandis is a species of major

importance for plantations with approximately 340 000 ha grown in South Africa. The species has

vigorous growth, and has good rooting ability, and pulping properties, but average to low wood

density and is highly prone to frost damage. Eucalyptus macarthurii is one of the few cold and frost

tolerant eucalypt species commercially planted on colder, high altitude and low productivity sites in

South Africa. Hybrids were developed by crossing E. macarthurii pollen (ex ICFR) onto E. grandis

selections (ex CSIR), and hedges were established in White River. Growth characteristics (diameter

at breast height and height) were evaluated in the E. grandis x E. macarthurii clones and controls, and

basal area calculated. The top performing clones were sampled for pulp yield and basic density.

Results showed that there were clones that performed better than, or equal to, the pure species

controls for diameter, basal area and height at the sites. The basic density of the top E. grandis x E.

macarthurii clones was higher than that of the E. grandis control, at sites where it was planted. The

pulp yield of the selected top clones was higher than that of both E. grandis and E. macarthurii, but

comparable to that of E. nitens and E. dunnii. Twenty clones were selected, based on diameter at

breast height, height and pulp yield, for further testing as having commercial potential for growth on

the more temperate sites of the summer rainfall regions of South Africa.


39

O16

Prediction of breeding values using classical genetic evaluation and genomic relationships in

a Eucalyptus grandis population

M.M. Mphahlele1,2

, G. Hodge3, F. Isik

3, A.A. Myburg

2

1Mondi Forests, Research and Development, Biotechnology, Mountain Home Estate, off Dennis

Shepstone Drive, Hilton, 3245, South Africa

2Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of

Pretoria, Private Bag X20, Pretoria, 0028, South Africa

3Department of Forestry and Environmental Resources, North Carolina State University, Campus

Box: 8002, Raleigh, NC, 27695 USA

Breeding values (BV) of an E. grandis population consisting of full-sibs, half-sibs, and trees with

unknown pedigree were predicted for seven growth and wood property traits. A total of 1558 trees

were genotyped using the EucHIP60K.Br SNP chip, generating 64639 SNP loci. After filtering the

SNP by call rate (<0.80) and minor allele frequency (<0.05), 21993 informative SNP were retained

with an average density of 1 SNP every 28.7kb. The BV were predicted based on phenotypic

(IBLUP), pedigree (ABLUP), realised genomic (GBLUP) and combined pedigree with realised

genomic (HBLUP) relationship matrices. The accuracy of predicting BV and the predictive ability of

the BLUP models are reported, averaged across randomly selected validation groups. The average

accuracy of predicting BV with GBLUP was 0.05 (s.d. = 0.01) higher (p < 0.05) across the traits

compared to ABLUP_G and for HBLUP it was 0.06 (s.d. = 0.03) lower (p < 0.001) compared to

ABLUP_H. The average predictive ability of IBLUP_G versus GBLUP across the traits was 0.12 (s.d.

= 0.10) higher (p < 0.05) compared to IBLUP_H versus HBLUP. The average predictive ability of

ABLUP_H versus HBLUP was 0.19 (s.d. = 0.04) higher (p < 0.001) with a bias range of 1.02 to 1.08

across the traits compared to ABLUP_G versus GBLUP with a bias range of 0.53 to 0.81. The

accuracy of predicting BV improved with GBLUP compared to ABLUP_G, and regressed with HBLUP

when compared to pedigree predicted non-genotyped full-sibs (ABLUP_H). The predictive ability of

IBLUP was higher with GBLUP compared to HBLUP and there was marginal bias between the

predictive ability of HBLUP versus pedigree predicted non-genotyped full-sibs. In conclusion, the

benefits of GBLUP in this E. grandis population was realised with limited or absent pedigree

information, and this benefit was transferable to non-genotyped full-sib trees using HBLUP.


40

O17

COMPARING FAMILY WITH INDIVIDUAL GENOTYPE SELECTION FOR SUGARCANE YIELD

AND ITS COMPONENTS FOR THE MIDLANDS BREEDING PROGRAMMES IN SOUTH AFRICA

N. Mbuma1, M.M. Zhou

1,2 and R van der Merwe

2

1South African Sugarcane Research Institute, Private Bag X02, Mt Edgecombe, 4300.

2Department of Plant Sciences, University of the Free State, P.O Box 339, Bloemfontein, 9300.

Family selection is the positive selection of an entire population of individuals from a cross and is now

widely practiced in sugarcane breeding. The objectives were to compare family with individual

genotypes selection (IGS) for cane yield, stalk number, stalk height and stalk diameter and evaluate

their implications at early stage of selection for humic and sandy soils breeding programmes in the

Midlands region of South Africa. Data for stalk numbers, height and diameter collected from seedling

progenies and used to estimate cane yield were analysed using the Statistical Analysis System. Both

family and individual genotype effects for all traits produced significant (P<0.001) variance. Family

variance was 1.2 to 5.0 times that of individual genotype variance indicating larger family variability

among families than individual progenies. The family broad-sense heritability (H) (25 to 90%) was

larger than that of individual genotypes (1.6 to 23.5%) suggesting selecting superior families would be

more accurate than individual genotypes. Populations grown on humic soils produced higher family H

(58 to 90%) than those from sandy soils (24 to 90%), indicating a higher precision of family selection

in humic soils. Families produced higher predicted selection gains (%Gs) (range 9 to 59%) compared

to individual genotypes (1.1 to 12%) indicating higher efficiency associated with family selection.

Humic soils populations produced higher average family %Gs (45%) than sandy soils (25%)

suggesting better selection efficiency. Humic soils provide uniform growth because they are less

prone to moisture fluctuation and have higher nutrient content than sandy soils. Significant family and

individual genotype variances indicates family selection followed by IGS within selected families will

increase efficiency in the first stage of sugarcane breeding. The larger family variance, higher H and

higher %Gs indicates superiority of family compared with IGS in the breeding programme.


41

O18

Location and crop-year effects on sugarcane genotype performance in the coastal short cycle

breeding programmes in South Africa.

S. Sengwayo 1, M.M. Zhou

1,2 and M. Labuschagne

2

1South African Sugarcane Research Institute, Private Bag X02, Mt Edgecombe, 4300.

2Department of Plant Sciences, University of the Free State, P.O Box 339, Bloemfontein, 9300.

In sugarcane breeding, advanced variety trials are planted at several locations and harvested in plant

and ratoon crops to evaluate genotype by environment interactions (GxE). Coastal short cycle crops

are harvested at 12-14 months. The objectives of this study were to determine the location and crop-

year effects and their implications on the coastal breeding programmes at Gingindlovu and

Empangeni. Data for yield, quality and agronomic traits were collected from five trial series planted at

five locations (two at Gingindlovu and three at Empangeni) and harvested in the plant and two ratoon

crops. Location effects were significant (P < 0.05) for TCH and TSH (yield traits) (2006; 2007) and

stalk height (2006), indicating potential environmental effects on genotype performance at different

locations. Genotype effects were highly significant (P < 0.0001) for all traits indicating large

differences between entries. Genotype by location interaction was significant (P <0.05) for brix %

(2003; 2004), yield traits (2006), dry matter % and fiber % (2003), indicating that ranking of genotypes

for these traits changed over locations. Crop-year effects were significant (P<0.05) for yield traits

(2003, 2006), brix % (2003 to 2006), estimable recoverable crystal (ERC %), Purity % and Pol %

(2005, 2005, 2007), stalk diameter (2007) and stalk height (2003, 2003), indicating seasonal effects.

Genotype by crop-year (GC) interaction was significant (P < 0.05) in all series for yield traits, ERC %,

Brix %, Pol % indicating that genotype performance fluctuated significantly across ratoons. Significant

GC suggests genotype performance is strongly influenced by the confounding effect of ratoon cycles

and seasonal variation. Crop-year had a larger influence on genotype performance than location

effects, therefore testing genotypes across more ratoons is more important. Selecting genotypes for

cane yield using stalk number, height and diameter (less-significant GC parameters) could reduce the

effect of crop-years.


42

O19

A Statistical view on wheat yield improvement: Its definition, measurement and significance

M. Booyse1, M. Labuschagne

2, K. Pakendorf

3, I. Heyns

4, A. Malan

4, E. von Well

4 and R. Lindeque

4

1ARC Biometry, P.O. Box 3279, Matieland, 7602

2Department of Plant Sciences, University of the Free State, P.O Box 339, Bloemfontein, 9300

3Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602

4ARC- Small Grain Institute, Private Bag X29, Bethlehem,9700

Wheat is the biggest winter cereal crop in South Africa and the second largest cereal to feed the

population of South Africa. The population of South Africa grows with approximately one million

people a year. Consistent wheat production is necessary for food security and is therefore of extreme

agricultural and economic significance. Future production increases depend on the ability to improve,

or at least maintain, the rate of increase to feed the population. The study was undertaken to

investigate genetic improvement (genetic advance) in wheat by various statistical methods of

analysis. This was done to determine the most suitable procedure to evaluate genetic improvement in

the three wheat production areas of South Africa, namely the Western Cape regions, the Free State

province and the irrigation areas. Linear regression (TRET) and various variance component methods

were investigated to determine genetic advance. The recommended method of determining genetic

advance in this study is TRET. In the Western Cape elite trials TRET predicted a genetic advance of

1% per year. No significant trend was observed in the elite trials of the Free State with TRET. A

genetic advance for yield of 0.7% per year was found in the warm region of the elite irrigation trials.


43

O20

Combining ability, Genetic Gains and Path Coefficient Analyses in a Maize Inbred Line

Population

I. Mathew

University of KwaZulu Natal, 2 Carbis Rd, Scottsville, PMB, 3201

Farmers in SSA continue to obtain low yields despite the high potential yield that can be achieved.

The wide gap between actual yields obtained and potential yield is partly due to growing of

unimproved varieties by the majority of farmers. The development of improved and high yielding

hybrids can help to reduce this gap significantly. Characterisation of maize inbred lines is crucial for

developing high yielding maize hybrids. A line x tester analysis involving 38 crosses generated by

crossing 19 maize inbred lines with two tropical testers was conducted for different agronomic traits.

The maize inbred lines used in this study were sampled from a bi-parental inbred population

developed by a shuttle breeding program at University of KwaZulu Natal. The objectives of the study

were to estimate combining ability of inbred lines and hybrids, to evaluate the performance of the

hybrids in agronomic traits and grain yield, to calculate breeding gains achieved through selection and

to deduce the relationship between secondary traits and grain yield. In total 50 hybrids, including

control hybrids were evaluated in the trial. The hybrids were planted in the summer season of 2014/15

under rainfed conditions at three sites, Cedara, Dundee and Ukulinga in five metre row plots and

replicated twice in 5X10 alpha lattice design under recommended agronomic practices for maize.

Data was collected using a CIMMYT protocol and subjected to statistical analyses using ANOVA and

REML packages in GENSTAT 14th edition and PATHSAS macros in SAS 9.3 computer software. The

results showed varying performances between the lines, crosses and control hybrids at the different

sites. Inbred lines DMSR-8, DMSR-13, DMSR-30 and DMSR-35-5 were shown to have good

combining ability while DMSR-21 and DMSR-73 showed positive specific combining ability. Selection

across sites improved grain yield by 9.32% over the population mean and by 10.22% and 12.73% at

Cedara and Dundee, respectively over commercial hybrids. Ranking by mean yield identified hybrids

15XH16, 15XH20 and 15XH28 at Cedara, Dundee and Ukulinga respectively, as the highest yielding

hybrids for that particular environment. GGE biplot and AMMI analyses revealed that hybrids 15XH10,

15XH13, 15XH20, 15XH25, 15XH28, 15XH34 and 15XH39 were the most stable hybrids. Secondary

traits were found to be associated with grain yield potential of hybrids. Ear prolificacy had the most

important relationship with grain yield and was recommended for selection in grain yield improvement

programs.


44

O21

Analysis of the genetic diversity of the South African Black wattle (Acacia mearnsii) breeding

population using SSR markers.

M.W. Bairu and W.G. Coetzer

Institute for Commercial Forestry Research (ICFR), P.O. Box 100281, Scottsville, 3209

The Institute for Commercial Forestry Research (ICFR) is the only research organisation undertaking

black wattle breeding in South Africa. To enable the conventional and operational breeding

programme, the ICFR recently developed an SSR-based fingerprinting tool. Genetic analysis of the

current breeding populations (218 trees in five populations) was done using a 11 marker ICFR

fingerprinting panel. Briefly, DNA was extracted using a modified CTAB protocol. Multiplex SSR-PCR

was performed using the KAPA2G Fast Multiplex kit. PCR products were then sent to Stellenbosch

University Central Analytical Facility for fragment analysis using capillary electrophoresis. The

electropherogram was read and alleles were scored using the GeneMarker software. The bi-allelic

data was then analysed by various software packages such as GenAlEx v6.5 (for estimation of

heterozygosity), STRUCTURE v2.3.4 and STRUCTURE harvester (for bayesian assignment analysis

to assess the pattern of genetic structuring), Populations v1.2.32 (individual genetic distances

between trees using Nei’s genetic distance) among others. The findings of the analysis will be

discussed.

O22

The influence of environment on some yield parameters of Taro (Colocasia esculenta).

W. Jansen van Rensburg1, P. Shanahan

2 and P.O. Adebola

1

1Agricultural Research Council, Private Bag X293, Pretoria, 0001

2African Centre for Crop Improvement, University of KwaZulu Natal, King George V Ave, Durban,

4041, South Africa

Taro (Colocasia esculenta), known as Amadumbe in South Africa, is a root crop that is traditionally

cultivated in the coastal and sub-tropical regions of South Africa. Taro is typically produced by small

holder farmers and traded informally, however, taro has commercial potential. Very little information is

available on the introduction and movement of taro in South Africa. No improved cultivars exists and


45

farmers plant local landraces of material that they have retain from the previous season. Furthermore,

there is also very little information available on the influence of the environment on specific genotypes

of taro.

ARC has built up a taro germpalsm collection that exists of local and foreign accessions. Twenty nine

of these accessions were planted at three localities, representing different agro-ecological zones.

These localities were Umbumbulu (South of Durban), Owen Sithole College of Agricultural (OSCA,

Empangeni) and ARC - Vegetable and Ornamental Plants (Roodeplaat, Pretoria). Different growth

and yield related parameters were measured. The data were analyzed using analysis of variance

(ANOVA) and additive main effects and multiplicative interaction (AMMI) analyses.

There was clear indication that environment influence some of the parameters like total yield and

number of cormels per plant. There was not a single accession that excel for all the characteristics in

all three the environments. However, there was some, like Thandizwe43, that were under the best for

most of the parameters. The yield (total weight of cormels) of accessions Nxele, Dlomodlomo19 are

stable over the three environments. The local accessions also perform better than the foreign

accessions. It is clear that some of the accessions do have the potential to be commercialized in

South Africa.

O23

Dough mixing characteristics measured by Mixsmart® software as possible predictors of

bread making quality in three production regions of South Africa

M. Labuschagne1, A. van Biljon

1 and R.C. Lindeque

2

1Department of Plant Sciences (Plant Breeding), University of the Free State, P.O. Box 339,

Bloemfontein, 9300

2ARC- Small Grain Institute, Private Bag X29, Bethlehem,9700

South Africa has three wheat production regions, the winter rainfall region where spring wheat is

planted; the summer rainfall where winter and intermediate wheat is cultivated; and the irrigation

region where spring wheat is grown. The aim of this study was to determine dough mixing

characteristics as measured by Mixsmart® software in these regions over two consecutive seasons in

two representative locations in each region, and to relate this to economically important quality

characteristics. In the winter rainfall area Mixsmart characteristics were very poor predictors of baking

quality. The best predictors of loaf volume in this region were flour protein content and wet gluten


46

content, which, in turn, were highly related. In the irrigation area, midline peak value and midline right

value were very good predictors of flour protein content, gluten content and loaf volume. Midline peak

value was highly correlated with protein content in both the irrigation and summer rainfall areas.

Envelope peak integral followed by midline right integral was the best predictor of loaf volume in the

summer rainfall area. From the correlations it would seem that the peak value is a better predictor

than peak time of baking quality, but a single parameter cannot fully describe the complexity of mixing

time. Several parameters from the mixograph have to be selected and used in multivariate statistical

analysis to obtain a more accurate prediction of loaf volume. This would be valid for the irrigation and

summer rainfall areas, but not the winter rainfall area.

O24

Total tocochromanol concentration in white and whole wheat flour of South African wheat

cultivars

A. van Biljon1, M.T. Labuschagne

1, N. Mkhatywa

1, B.S. Wentzel

2 and E. Johansson

3

1Department of Plant Sciences (Plant Breeding), University of the Free State, P.O. Box 339,

Bloemfontein

2Small Grains Institute, P.O. Box 29, Bethlehem, South Africa

3The Swedish University of Agricultural Sciences, Department of Agrosystems, Box 104, Alnarp,

Sweden.

Wheat is well known for its bread-making and baking qualities. However this important cereal is also a

good source of fiber, phenolics, carotenoids and vitamin E, also called tocochromanol.

Tocochromanols are only synthesized in plants and important because of their antioxidant activity.

Making vitamin E an important component in any diet. The aim of this study was to determine the

tocochromanol content in white and whole wheat flour of ten South African cultivars grown at three

different locations. Saponification and normal phase-high performance liquid chromatography was

used to separate the compounds. Total tocochromanol concentration in genotypes ranged between

16.49 - 25.49 mg kg-1

for white flour and 41.92 - 54.87 mg kg-1

for whole wheat flour. The

tocochromanol was, on average, 60% higher in whole wheat flour. Tocochromanol compounds

consists of eight lipid-soluble antioxidants: alpha-, beta-, gamma-, delta-tocotrienol and alpha-, beta-,

gamma-, delta-tocopherol. The major compounds found in the samples were alpha- and beta-

tocotrienols and alpha- and beta-tocopherols. Alpha-tocotrienol and alpha-tocopherol were more than

75% lower in white flour compared to whole wheat flour while beta-tocotrienols were only 47% lower

in white compared to whole wheat flour. Only traces of delta-tocochromanol compounds were found in


47

all samples. Results also indicate environment and genotype and the interaction between the two,

influenced tocochromanols significantly. In conclusion, the variation in tocochromanol content

between cultivars suggests that some will be a better source of tocochromanols allowing for selection

for increased tocochromanol content in the breeding process.

O25

Multivariate statistical analysis of some bread quality traits for South African commercial

wheat cultivars

J. Onsando1, A. van Biljon

1, B.S. Wentzel

2, M.T. Labuschagne

1

1Department of Plant Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South

Africa

2 Small Grain Institute, P.O. Box 29, Bethlehem, 9700, South Africa

Selected wheat quality parameters were evaluated in 51 wheat cultivars from three different breeding

programmes. Trials were based on a randomised complete block design with three replications.

Principal component analysis (PCA) and factor analysis were conducted to understand the data

structure, cultivars and trait relationships. In all three breeding programmes principal component (PC)

1-5 explained approximately 90% of the total variations among the trails. The first PC explained

34.16% of variation in the summer rainfall programme (DLS), 38.83% in the winter rainfall programme

(DLW) and 38.62% in the irrigation programme (IRR). The second PC explained 24.15% (DLS);

23.50% (DLW) and 24.91% (IRR) of variation respectively. Selection may be done based on the first

PC and it will be helpful in the breeding programmes for development of cultivars with good bread

quality traits. The most prominent relations were found between dough extensibility and dough

strength in all the breeding programmes. The bi-plots indicated specific cultivars could be selected as

parents, as they are closely associated with a quality trait of interest in the different breeding

programmes. The knowledge generated from the PCA will assist breeders in making selections thus,

reducing costs required to obtain the genetic parameter estimates necessary to construct selection

indices.


48

O26

Heritability and expression of selected mixogram parameters in progeny of parents varying for

mixing time

F.S Pelser1, A. van Biljon

1, B. Wentze

2 and M.T. Labuschagne

1

1Department of Plant Sciences (Pant Breeding), University of the Free State, P.O. Box 339,

Bloemfontein 9300, South Africa.

2Small Grains Institute, Private Bag X29, Bethlehem 9300, South Africa

In baking, the first step is to mix flour and ingredients with water. When water is added to the flour it

becomes hydrated and viscoelastic dough forms).

Mixing time is an indication of time that is needed for dough to reach maximum consistency. Not

much is known about the inheritance of mixing time in South African wheat cultivars. The aim of this

study was to determine the expression and the heritability of mixing time and related characteristics in

selected parents and their F1 progeny. Six parents were crossed in the greenhouse in all

combinations in a diallel mating design, excluding reciprocals, to produce 15 F1 progeny. The F1

progeny and parents were planted in Orania, Petrusburg and Maggogong in a randomised complete

block design with three replications. The grains were conditioned, milled and subjected to mixing time

analysis using Mixsmart® software. General combining ability (GCA) and specific combining ability

(SCA) of the parents as well as the narrow sense heritability for the characteristics was calculated

using Agrobase software. Midline-development time, -peak integral and -peak time showed very high

narrow sense heritability. Envelope peak-integral and -tail width displayed high narrow sense

heritability at some locations. High GCA:SCA ratios indicated the prevalence of additive gene effects

for midline-development time, -peak integral and -peak time, indicating that these characteristics are

largely genetically determined, and that selection for them should lead to genetic gain.


49

O27

Development of near-infrared (NIR) models for prediction of wood and pulp traits for the

forestry industry

S. Naidoo , W. Naidoo, R. Ismail and A. Kanzler

Sappi Forests Research, Planning and Nurseries, Shaw Research Centre, P.O. Box 473, Howick,

3290

High dimensional near-infrared (NIR) spectral data can detect multi-traits of chemical, physical,

mechanical and anatomical properties of wood materials. Chemical analyses can be slow, expensive

and require sophisticated laboratory equipment and trained staff, whereas NIR spectroscopy

potentially offers a very high correlation between the laboratory based “wet chemistry” results and the

NIR spectral data. Consequently, the advantages of NIR spectroscopy include ease of use, speed (30

seconds for multiple assays), simultaneous analysis of several components, non-pollutant, non-

invasive and non-destructive assays, and the possibility of online or field implementation. In this

study, NIR models were developed to predict screened pulp yield, total lignin and glucose content in

Eucalyptus trees. PLS regression with a variable selection methodology was used for modelling

purposes. The final models exhibited low validation errors (RMSE values between 0.80 and 1.30) with

high predictive abilities (R2 values between 0.73 and 0.9). These models provide a quick and

inexpensive method of phenotyping wood property traits in the forestry industry. Robust and reliable

models, based on large sample sizes allow for the prediction of trait levels, which will enhance the

value of this technology to applied research in the wood and paper industry. These models have been

successfully used to predict phenotypes in biotechnology, breeding and land management trials.


50

O28

CHARACTERISATION OF STONE-FRUIT GENOTYPES OF THE ARC BREEDING PROGRAMME

IN TERMS OF CAROTENOID PROFILES AND ASSOCIATED FRUIT QUALITY TRAITS

W. Pieterse1 , M.A. Vivier

2, P.R. Young

2, K.R. Tobutt

1

1Cultivar Development Division, ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599

2Institute for Wine Biotechnology, Stellenbosch University; Private Bag X1, 7602, Matieland, South

Africa

Stone-fruits such as peach (Prunus persica), apricot (P. armeniaca) Japanese plum (P. salicina) and

almond (P. dulcis) have been cultivated for ~ 4000 years and in South Africa for ~ 300 years. The

value of the South African stone-fruit industry amounts to ~ R1 700 million, with a combined export

volume of ~ 75 000 tons. Breeding programmes have been developing cultivars for the last ~ 100

years. At ARC, stone-fruit breeding programmes focus on consumer and grower requirements such

as taste, texture and appearance and high productivity, with disease resistance and different

harvesting dates. Peach and Japanese plum are diploid with 2n = 2x = 16 chromosomes. Peach is

less heterozygous than plum as a consequence of self-compatibility. Peach is highly characterised

genetically and is considered as a model species for the family Rosaceae with not only linkage maps

in various progenies but also the genome sequence. Peach flesh colour (white vs. yellow) is

controlled by a single locus (Y) mapping to linkage group 1 and the yellow is due to carotenoids. The

alleles responsible for yellow colour have recently been attributed to mutations in the gene PpCCD4

which encodes a carotenoid cleavage dioxygenase enzyme. Carotenoids such as β-carotene are

important components of fruit quality affecting flavour and colour since carotenoids serve as

precursors of norisoprenoids. The presence of norisoprenoids depends on carotenoid concentration.

We are currently investigating carotenoid-derived quality impact factors of peach and plum,

specifically fruit-flesh colour and aroma compounds and are conducting a comparative analysis to

determine the natural diversity available in parents and profiling segregating progenies to analyse the

inheritance of carotenoid-derived traits. Depending on the results obtained, mapping studies with

microsatellites and/or SNP chips are tentatively planned to locate possible Quantitative Trait Loci or

major genes. It is hoped to present preliminary results.


51

O29

MOLECULAR CHARACTERISATION OF THE ARC APPLE COLLECTION WITH RESPECT TO

THE ACS1 GENE INVOLVED IN FRUIT ETHYLENE PRODUCTION

K.G. Mhelembe 1,2

, J.H. Kriel1, C. Bester

1, R. Roodt-Wilding

2, E.D. Louw

3 and K.R. Tobutt

1

1Cultivar Development Division, ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599,

South Africa

2Department of Genetics, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa

3Department of Horticultural Science, Stellenbosch University, Private Bag X1, Matieland, 7602,

South Africa

Apple (Malus pumila Mill.) is the second most important deciduous fruit crop after grape in South

Africa. Approximately 40% of the produce is exported to the Northern Hemisphere markets. Over-

maturity of fruits upon arrival at distant markets would lead to rejection of shipments, making storage

potential an important objective in the apple breeding programme conducted by Agricultural Research

Council’s Infruitec-Nietvoorbij. Phenotyping of fruit characteristics in apple progenies is protracted due

to the long juvenile phase. However, the enzyme aminocyclopropane-1-carboxylic acid synthase

(ACS) is known to be involved in production of ethylene by the fruit during ripening. The ACS1

genotypes, associated with an indel in the promoter region of the gene, are known to correlate with

ethylene production – aa, high ethylene production; ab, medium; or bb, low ethylene – making

molecular characterisation an effective approach. The accessions in the ARC gene bank have

recently been fingerprinted to confirm trueness to type. A total of 292 accessions, mostly of M. pumila

and some closely related Malus species, regarded as true to type, were genotyped for the ACS1

variants. New primers for ACS1 were designed that can be fluorescently labelled and result in smaller

products compared to the published primers and allow automated sequencing instead of gel

electrophoresis. Of the 256 M. pumila accessions, 118 were aa, 109 were ab and 29 were bb.

Knowledge of ACS1 genotypes will help the design of crosses for low ethylene production associated

with late ripening. The primers will be useful for marker-assisted screening of segregating progenies

to reduce the number of seedlings planted in the field and allow for early identification of cultivars with

good storage potential.


52

O30

Understanding Apple Russet: A Molecular, Genetic and Metabolomic Viewpoint

J. Lashbrooke1, K. Tobutt

2, A. Aharoni

3 and F. Costa

1

1Research and Innovation Centre, Fondazione Edmund Mach Via E. Mach 1, San Michele all'Adige,

38010, TN, Italy

2ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch, 7599

3Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel;

Apple russet, the phenomenon involving cracking of the apple fruit cuticle and subsequent production

of a corky suberized layer, can be viewed as either a defect or an attribute in apple breeding. While

there are a number of historically important russeted cultivars, and a niche market for these apples

still exists (at least in Europe), typically the formation of russet on the surface of apples is considered

undesirable by today’s consumers. While environmental factors have been found to influence russet

formation, there is strong evidence for genetic control of this phenotype. Mapping of QTL regions

linked to russet formation was performed in the progeny of a ‘Golden Delicious’ and ‘Braeburn’ cross,

and candidate genes screened. This led to the identification of an APETALA2-domain transcription

factor which is likely essential for proper cuticle development and which was found to be defective in

expression in russeted lines. Further large-scale expression analysis and metabolomic analysis

comparing russet and normal cultivars was performed. These results together with recently published

public data paint a picture for the russet formation as a secondary phenotype resulting from the

improper cuticle formation. As such there are multiple loci which may underlie a failure of the apple to

form functional cuticular layer, and hence lead to russet formation. Understanding cuticle formation in

apple russet, and identifying key genes, will allow breeders to select both for, and against, russet

formation.


53

O31

Evaluation of Genetic Diversity within South African Sugarcane Breeding Populations and its

Implication on Breeding

L Makome 1, S. Joshi

1,2 and M. Ghai

2

1South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, South

Africa

2University of KwaZulu-Natal, King George V Ave, Durban, 4041, South Africa

The South African Sugarcane Research Institute (SASRI) breeding programme relied solely on

phenotypic characteristics to structure the breeding population for variety improvement, which are

influenced by environmental conditions. The current study was undertaken to evaluate the genetic

diversity within SASRI breeding populations using molecular markers, which are known to be stable.

A total of 11 genomic microsatellites (gSSRs) and 10 Expressed Sequence Tag microsatellites (EST-

SSRs) were used in this study. The sampled population consists of 557 genotypes, comprising of a

subset of 470 genotypes selected from different SASRI breeding programmes including released

varieties and 87 wild/related sugarcane clones. Genetic diversity was assessed at two levels: within

and between breeding populations. Out of 11 gSSRs tested, only eight were amplified, while only six

EST-SSRs were amplified. gSSRs produced a total of 242 alleles, ranging from 64 to 476 base pairs

(bp), whereas, EST-SSRs produced 134 alleles ranging from 70 to 575 bp. GenAlExV6.501 was used

to calculate polymorphic information content (PIC) values, genetic distances, Mantel correlations, and

Principal Co-ordinate Analysis (PCoA). Dendograms were generated using Randomised Axelerated

Maximum Likelihood (RAxML). The PIC value for gSSRs was higher, ranging from 0.71 (SEGMS840)

to 0.88 (SMC569CS) with an average of 0.77 compared to EST-SSRs, which ranges from 0.44 (EST-

SSR45) to 0.69 (ESTA63) with an average of 0.60. PCoA and phylogenetic analysis were able to

classify wild and related species into three groups. Furthermore, both analyses were able to reveal

low genetic diversity exists within and between breeding populations. The Mantel correlation test

revealed the decline in genetic diversity over a period of 50 years. We conclude that both marker

types either in combination or individually, were effective in depicting the diversity within/among

populations. The current outcome will assist breeders to develop strategies to improve and maintain

genetic gains through introgression breeding.


54

O32

The status of South African plantation forestry gene conservation and the development of a

conservation strategy for the industry

A. Kanzler 1, T. Swain

2, S. Verryn

3, F. van Deventer

4, W. Jones

1 and A.A. Myburg

5

1Sappi Forests Research, Planning and Nurseries, Shaw Research Centre, P.O. Box 473, Howick,

32902

2Institute for Commercial Forestry Research, P.O. Box 100281, Scottsville, 3209.

3Hans Merensky

4Mondi

5Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of

Pretoria, Private bag X20, Pretoria, 0028.

Fast-growing tree plantations are cultivated on around 1.2 million hectares and contribute significantly

to the South African economy, supporting around 170,000 jobs and a R25 billion industry. Over the

last century, South Africa has been importing, testing and commercializing a wide range of tree

species and populations that have contributed hugely to the success of the forest industry today.

However, climate change and globalisation has led to increasing abiotic stress, as well as biotic

stresses such as disease and insect attacks, highlighting the need for breeders to be more proactive

to manage rapid environmental and market changes. Consequently, it is argued that a systematic and

well managed national gene conservation strategy for fast-growing plantation trees is urgently needed

and that this should include multiple role players - including private industry, government and other

public institutions such as universities. A plan is presented that attempts to integrate and compliment

the needs of tree breeders, industry and gene conservation. It ‘should not be directed at maintaining a

forest population in a given state forever, but rather at ensuring the long-term enhancement of the

genetic diversity available to meet future human needs’. This strategy will need to ensure maximise

genetic diversity, both across and within species; facilitate the rapid transfer of genotypes from

conservation banks into breeding programs as and when needed; and link phenotyping to genetic

diversity so that breeders can understand / quantify the significance and value of the conserved

material. The achievement of these objectives will be dramatically enhanced with the use of genome-

wide DNA genotyping technology (population genomics) along with other new technologies (such as

remote sensing) so that we can better integrate and utilise phenotypic information from the tree with

environmental variables on a landscape level.


55

O33

Ten years of genotypic analysis of the three wheat rusts in Southern Africa

B. Visser1, T. Terefe

2, L. Herselman

1 and Z. Pretorius

1


Africa

2Agricultural Research Council-Small Grain Institute, Private Bag X29, Bethlehem 9700, South Africa

Wheat (Triticum aestivum L.) acts as host for three Puccinia spp. causing stem rust (P. graminis Pers.

f. sp. tritici Eriks. and E. Henn; Pgt), leaf rust (P. triticina Erikss.; Pt) and stripe rust (P. striiformis

Westend.; Ps) respectively. Traditional identification of rust races depends on their infection profiles

on a defined wheat differential set. Since 2007, we have successfully implemented microsatellite

marker analysis at the University of the Free State to complement race phenotyping. Results have

indicated that both the Pgt and Pt populations consist of two separate lineages, while for Ps a single

clonal lineage is present. The composition of all three rust populations is dynamic, with both local

adaptation and foreign introductions contributing to changes within the population. These proposed

introductions are mainly from neighboring countries that form a single epidemiological region with

South Africa. Genetic analysis of field isolates collected during annual surveys conducted by the

ARC-SGI in Bethlehem, confirms the overall structure of the Pgt and Pt populations, but also showed

that multiple genotypes can exist for a single phenotype. This is despite the fact that the sexual phase

of Pgt and Ps that is completed on Berberis spp. has not been reported in South Africa. Finally,

genotypic analysis of selected South African and Australian races supports previous indications of Pgt

urediniospore movement across the Indian Ocean and its establishment in Australia.


56

O34

Pathogenomics of South African stripe rust in a global context

H.J. van Schalkwyk1, R. Prins

1,2, Z.A Pretorius

1, L.A. Boyd

3, C. Uauy

4 and D.G.O. Saunders

4

1University of the Free State, Bloemfontein 9300, South Africa

2CenGen (Pty) Ltd, South Africa

3NIAB, Huntingdon Road, Cambridge CB3 0LE, UK

4John Innes Centre, Norwich Research Park, Colney Ln, Norwich, NR4 7UH, UK

Stripe (yellow) rust, caused by the fungus Puccinia striiformis f. sp. tritici (PST), is a major global

wheat disease. New PST strains that show higher infection rates and rapid adaptation to previously

regarded less favourable environmental conditions have been observed over the last 15 years.

Consequently it continued to spread to areas where it was not previously recorded. In South Africa

(SA), the first stripe rust occurrence was detected in 1996, and more races were detected in

subsequent years. A better understanding of the South African PST pathotypes and how they fit in the

global context is needed. We aimed to address this by sequencing the genomes of four historical PST

isolates displaying the four distinct virulence profiles. This allowed us to place the historical South

African PST isolates in context with global PST isolates where sequence data was available. This

analysis illustrates that the historical South African PST races are more closely related to PST from

other African countries when compared to isolates from Africa, Europe and Asia. Through pairwise

comparison of isolates, we identified candidate effector genes showing specific polymorphisms

between the four isolates that could be related to their distinct virulence profiles. We are currently

undertaking gene expression profiling of these candidates to determine if these effectors are

specifically upregulated during infection–a key characteristic of effector genes. This study has shed

new light on the potential origin and adaptation of stripe rust in South Africa and will provide tools for

rapid genotypic classification of infections in the field.


57

O35

Improved genetic characterisation of the slow rusting stripe rust QTL (QYr.sgi-4A.1) region of

Kariega through SNP array analysis

C. Smit1, S. Krattinger

2, M. Horn

3 and R. Prins

1,4

1CenGen (Pty) Ltd, 78 Fairbairn Street, Worcester, 6850, South Africa

2Institute of Plant Biology - University of Zurich

3Sensako (Pty) Ltd


Africa

Kariega was the first wheat cultivar in South Africa to be subjected to a linkage mapping approach to

unravel the genetics of a quantitative trait. Using a QTL analysis approach, its adult plant stripe rust

resistance components were determined and verified i.e.: Lr34/Yr18/Sr57/Pm38 (7D), QYr-sgi.2B.1

(2B) & QYr-sgi4A.1 (4A). The multi-pathogen Lr34/Yr18/Sr57/Pm38 resistance gene is one of a

handful of genes that has proven to be effective against all three wheat rusts over decades. Cloning

of the Lr34/Yr18/Sr57/Pm38 slow rusting gene on 7D revealed that it encodes a full-size ATP-binding

cassette (ABC) transporter of the ABCG subfamily, which is different to the nucleotide-binding site

leucine-rich repeat (NBS-LRR) family of resistance genes the predominant number of single/major

genes consist of. Doubled haploid lines were developed in the same genetic susceptible background

and the QYr.sgi-4A.1 region was targeted for the identification of informative SNPs by submitting

these lines, together with the appropriate control lines, for analysis on the Illumina iSelect 90K wheat

SNP array. A high resolution mapping population is under construction to map these SNP markers in

an attempt to delimit the QTL region on 4A to a clonable distance. The cloning of this gene will

contribute towards a better understanding of the underlying mechanism of slow rusting resistance.


58

O36

Development of wheat lines with complex resistance to rusts and Fusarium head blight

A. Maré , H. Castelyn, Z. Pretorius and L. Herselman

Department of Plant Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South

Africa

Sustainable wheat production in South Africa is of economical importance for farmers, the milling

industry and consumers. Wheat production is affected by a number of fungal diseases, especially leaf

rust, stem rust, stripe rust and Fusarium head blight (FHB). The aim of the study is to combine

durable rust and FHB resistance into a single wheat line and to use different phenotypic and

molecular screening methods to evaluate these lines. Wheat lines with resistance to the three rusts or

FHB were developed from two different breeding programmes at the University of the Free State.

Three rust resistant lines were selected as female parents containing the following rust resistance

genes/quantitative trait loci (QTL): Lr19, Lr34/Yr18/Sr57, Sr2, Sr26, Sr39 and QYr.sgi-2B.1. FHB

resistant BC2F2 and BC2F6 lines were selected as male parents, containing different combinations of

Fhb1, Qfhs.ifa-5A-1 and Qfhs.ifa-5A-2. Molecular markers were used to confirm the presence of the

expected genes/QTL in the putative parents. More than 100 crosses were made between the best

identified rust and FHB resistant lines. Since these selected parents were not homozygous for all

markers, the generated six-week-old F1 seedlings were screened using molecular markers to identify

the best plants for combining rust and FHB resistance in the double cross population. Nine genotypes

with different rust resistance gene/QTL combinations were selected for phenotypic evaluation in the

greenhouse at both seedling and adult plant stages. Rust infection was furthermore evaluated by

quantifying the biomass accumulation of the inoculated pathogen in each genotype using reverse

transcriptase real-time polymerase chain reaction (RT-qPCR) analysis. The presence of the expected

rust resistance genes/QTL was confirmed using marker-assisted selection. Results indicated that RT-

qPCR results correlated with infection type scores and the combination of genes/QTL present.


59

O37

Multi-environment evaluation of maize inbred lines for resistance to Fusarium ear rot and

fumonisins.

L. Rose1 , M. Mouton

1, I. Beukes

1, B. Flett

2, C. van der Vyver

3 and A. Viljoen

1

1Department of Plant Pathology, Stellenbosch University, Private Bag X1, Matieland, 7602, South

Africa.

2Grain Crops Institute, Agricultural Research Council, Potchefstroom, South Africa.

3Institute of Plant Biotechnology, Stellenbosch University, South Africa.

Fusarium verticillioides causes Fusarium ear rot (FER) of maize and produces fumonisins which

affects grain quality. Host-plant resistance can reduce both FER and fumonisins in maize. In this

study, 18 maize inbred lines were evaluated for resistance to F. verticillioides and fumonisins at five

localities in South Africa. Additive main effects and multiplicative interaction analyses revealed

significant environment x genotype interactions, with inbred lines CML 390, US 2540W, RO 424W

and VO 617y-2 consistently exhibiting low FER severity (≤ 5%), fungal biomass (≤ 0.1 ng μl-1) and

fumonisin levels (≤ 5 ppm). Genotype main effect and genotype x environment (GGE) biplots showed

that inbred lines CML 390, US 2540W, RO 424W were most resistant to FER, fungal colonization and

fumonisin accumulation, respectively, while inbred line RO 424W was most stable in its resistance

response over environments. These inbred lines also demonstrated broad adaptability by consistently

exhibiting resistance to FER, fungal colonization and fumonisins across localities. The identified lines

could serve as valuable sources of resistance against F. verticillioides and its fumonisins in local

breeding programmes.


60

O38

Standardizing sugarcane thrips (Fulmekiola serrata) damage, identifying molecular markers,

and its implication for resistance breeding

S. Joshi1,2

and M. Zhou1,3


Africa

2School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-

Natal, South Africa

3Department of Plant Breeding, University of the Free State, Bloemfontein, South Africa

Sugarcane thrips, Fulmekiola serrata Kobus emerged as a major pest in the South African sugarcane

industry since 2007. Breeding and selecting resistant genotypes is one of the strategies to control the

pest. This study was to establish a method for routine resistance screening for thrips. Currently, thrips

numbers count is used to rate genotypes. However, it is time consuming and labour intensive. A new

method to evaluate the phenotypic damage caused by thrips was developed by comparing thrips

number and phenotypic damage. Ninety genotypes were planted in replicated field trials at the SASRI

Mount Edgecombe and Kearsney research stations in KwaZulu-Natal. Leaf damage data were

collected on a three month old crop, for three consecutive months over three seasons. One spindle

per plot was sampled from the three month old crop to count the number of thrips. Data were

analysed by genotype, month and years as fixed effects. Significant differences (P<0.0001) were

recorded between years and sites for both traits. Significant differences (P<0.0001) exist among

genotypes for thrips damage. Although the F value (F=3.72, P<0.0001) for thrips numbers was

significant, it was lower than those for thrips damage (F=17.37, P<0.0001), indicating a lower

discrimination among genotypes when using a thrips number parameter. Thrips damage in genotypes

was highly correlated across all site/season combinations when compared with thrips numbers. The

coefficient of variation was found to be much larger (61.37%) for thrips number compared with thrips

damage (14.59%). The parameters indicate that thrips numbers are less reliable for determining

genotype differences compared with thrips damage. Thrips damage based on phenotypic symptoms

will be recommended for routine resistance screening. Putative molecular markers were identified for

either resistance or susceptibility. Markers for susceptibility were more predictable than for resistance,

therefore eliminating susceptible genotypes will be a more effective means for parent selection rather

than identifying resistance genotypes.


61

O39

Evaluation of cowpea varieties for bruchid (Callosobruchus rhodensiansus) resistance in

South Africa

I.M. Letsoalo and J.A.N. Asiwe

University of Limpopo (Turfloop Campus), Department of Plant Production, Soil Science and

Agricultural engineering, Private Bag X1106, Sovenga, 0727 South Africa.

Cowpea serves as a source of protein and carbohydrates in the diets of many people in developing

countries. Production of cowpea in South Africa is limited by damage in storage by bruchids. To solve

this problem, new introductions of cowpea varieties were made and evaluated for bruchid resistance.

The experiment was conducted in the Plant Production Laboratory of University of Limpopo. The

experiment was laid in a randomized complete block design (RCBD) with 3 replications. Fifty five

cowpea varieties obtained from A&M Texas University, USA was used with Ife brown as control

check. For uniform infestation, only one egg was retained on the seed and excess was carefully

removed by scraping using razor blade. Data collected included percent adult emergence, number of

days to insect emergence, mean developmental time, total developmental time, damaged seed and

seed weight loss.

Results obtained from the study showed high significant variation in the variables measured. Majority

(93%) of 55 varieties performed better than the susceptible check Ife brown which showed low level of

resistance to bruchids. There was a strong correlation between percentage adult emergence and

seed weight loss (r= 0.85)\, as well as between percentage of damaged seeds and seed weight loss

(r= 0.84). Based on the mean developmental time (MDT), top five varieties with longer mean

developmental time were selected and regarded as promising varieties for bruchid resistance with a

range of 13-20 days. The varieties include IT83D-442, IT98K-476-8, Mouride, IT98K-1092-1, IT82D-

889, and are recommended for cultivation or for breeding purposes in South Africa.

62

Abstracts of poster presentations

P1

Shortcutting cuttings

W. Brink and T. Le Roux


Speeding up the selection and deployment of productive forestry clones can result in increased profit.

Traditionally, progeny are selected based on volume, cloned and then tested in greater numbers and

selected based on mass, a product of density and volume. If density is unchanged from progeny to

clone, it would be possible to select progeny based on mass. This poster focuses on the transfer-

ability of density from progeny to clone and possible changes in testing strategy.

P2

Molecular Mapping of Fusarium Head Blight Resistance Genes in Wheat

C. Dweba1, T. Tsilo

1 and H. Shimelis

2

1Agricultural Research Council - Small Grain Institute. Private Bag X29, Bethlehem 9700

2University of KwaZulu-Natal, African Centre for Crop Improvement, Private Bag X01, Scottsville

3209, Pietermaritzburg, South Africa

Fusarium Head Blight (FHB) is a devastating disease of wheat and barley caused by a complex of

Fusarium species, predominantly F. graminearum. The causative pathogens produce various

mycotoxins that pose a threat to human and animal health, with major quality and yield reductions.

Major outbreaks have been reported globally, with devastating economic implications. Various

strategies have been deployed in attempts to alleviate the occurrence and impact of FHB worldwide,

however, no control strategy has been proven to be 100% effective. Genetic control remains the most

effective and environmentally sound control strategy as it exploits the host plant resistance

phenomenon of the plant’s ability to successfully resist damage by host pathogens using resistance

genes. Phenotypic scoring of the disease is the first step in elucidating the resistance of the

populations. The objective of this study is therefore to phenotype Recombinant Inbred Lines (RILs)

11th SAPBA Symposium Poster presentations

63

developed from five new resistance sources and thereafter identify the most promising potential

source(s) of resistance to be introduced into the South African germplasm. Approximately 27% of the

RILs displayed a FHB score greater that 50% in the first year of planting. This result shows that most

of the RILs in this mapping population show some resistance to FHB with approximately 18% having

≤10% disease score. Two of the lowest scoring new resistance sources were the 10th entry from the

9th SCAB nursery and the 36th entry from the 10th SCAB nursery with scores of 14% and 16%

respectively. This is congruent with the results of the RILs scoring as the lowest scoring lines are

progenies of the two parental lines. In Bethlehem, 37.01% of the lowest scoring lines had parent 9th X

10 and 25.9% had parent 10th X 36. In Cedara, 27.46% of the lowest scoring lines had parent 9th X

10 and 34.51% had parent 10th X 36. Confirmation of field results is currently being carried out, with

the population planted in Bethlehem, Qwa-Qwa and Cedara, allowing for screening in multiple

environments. Preliminary results show this mapping population to have lines with significant

resistance to FHB, however, concluding remarks and recommendations should be made after the

second field planting results have been obtained as well as verification by genotyping.

P3

Field Performance of Three Generations of Tepary Bean Mutants

E.T. Gwata1, A. Thangwana

1, H. Shimelis

2 and M.M Zhou

3

1Department of Horticulture, University of Venda, Private Bag X5050, Thohoyandou 0920, South

Africa




Africa

Tepary bean (Phaseolus acutifolius) is an important food legume cultivated in semi-arid areas in many

parts of the world including the Sekhukhune district in Limpopo Province, South Africa. It is highly

tolerant to drought but generally low yielding. The genetic improvement of the crop is limited by a

narrow genetic base. However, the genetic base can be broadened through induced mutagenesis.

Chemical mutagenesis using ethyl methanesulfonate (EMS) could provide agronomically diverse and

promising mutants of the crop for selection. This study examined the agronomic performance of early

generation tepary bean mutants under field conditions at Thohoyandou (220 58’ S, 300 26’ E; 596 m

a.s.l.) in Limpopo Province. The seed of three mutant populations (M2, M3 and M4) of tepary bean that

was derived from each of three different genotypes using varying doses of EMS (0.0; 0.5; 1.0; 1.5 and


64

2.0) was planted in a field experiment laid out as a 3 x 3 x 5 (genotype x generation x EMS dose)

factorial design arranged in randomized complete block design replicated three times. The mutant

generation significantly (P<0.01) influenced shoot dry weight (SDW), number of pods per plant (NPP)

and 100 seed weight (100-SW). In addition, there were highly significant (P<0.01) genotypic effects

on the number of seeds per pod (NSP). The mean NPP was 15.55 while the 100-SW was only 8.60 g

on average. The SDW decreased markedly (by >25.0%) with the mutant generation but seed size

was similar among the three genotypes. A negative but highly significant (P<0.01) linear relationship

was observed between the NPP and NSP. The results suggested that in mutation breeding for tepary

bean, it is important to consider each of the three factors in order to induce desirable agronomic traits.

P4

Molecular characterisation of new sources of adult plant resistance to wheat rusts

S. Figlan1, T.J. Tsilo

1, H.A. Shimelis

2

1Agricultural Research Council – Small Grain Institute (ARC-SGI), Private Bag X29, Bethlehem, 9700,

South Africa



One of the major challenges in employing genetic control of wheat rusts is that the physiologic races

of the pathogen frequently acquire new virulence to overcome effective resistance in existing

cultivars, particularly when resistance is conferred by race-specific genes. In this study, a Nested

Association Mapping (NAM) approach was used to map resistance gene loci with a higher power and

resolution and to possibly identify novel quantitative trait loci (QTLs) conditioning resistance to stem

(black), leaf (brown) and stripe (yellow) rust caused by Puccinia graminis, P. triticina and P. striiformis

respectively. In addition, the genotyping by sequencing (GBS) method was used to dissect and

understand the genetic architecture controlling rust resistance in the NAM populations. The NAM

panel was developed by crossing eight sources of resistance from Kenya with two cultivars adapted

to South Africa, generatingF6:8 recombinant inbred lines (RILs). The RIL populations were

phenotyped in 6 South African localities viz. Tygerhoek (2014 and 2015), Bethlehem (2014 and

2015), Cedara (2014 and 2015), Clarens (2015), Fouriesburg (2015) and Qwaqwa (2015). One

population of 180 lines from the NAM panel showing good segregation for all three rusts was

genotyped with Diversity Array Technology (DArTs) markers. QTLIciMapping software was used to

construct a genetic linkage map incorporating all the informative Single Nucleotide Polymorphism

(SNP) and DArT marker information. When linking the genotype to the phenotype (QTL mapping), a


65

common QTL (Lr34) with main effects was identified on chromosome 7D. Several other QTLs of

minor and medium effect contributing towards seedling and adult plant resistance to the three rusts

were identified, showing the presence of significant diversity of genes with minor effect on rust

resistance in the developed RIL population. Validation of the identified QTLs using the second year

phenotype data over several locations is on-going. This is necessary to generate diagnostic markers

for marker assisted resistance breeding and pyramiding of resistance genes in elite breeding lines.

P5

Impact of disease on Forestry in the Subtropical area of Zululand and future plans to monitor

the occurrence of new diseases

G. Galloway, T. Le Roux and A. Kanzler


Over the past few years decreased rainfall and the increased rate of introduction of new pests and

diseases have had a negative impact on forestry in the coastal areas of Zululand. Over the last 50

years the rate of introduction of diseases and pests has increased exponentially. This has affected the

mean annual increment (MAI) of Sappi Forests. Sappi has devised a plan to monitor the introduction

of new pests and diseases into subtropical Zululand in order to mitigate the impact on Forestry. This

will be done by establishing blocks of approximately 100 clones strategically over the subtropical

landholdings of Sappi. These blocks will be managed so that at all times there is juvenile and mature

foliage available in order to monitor pest and diseases. Sappi has to a large extent characterized the

two main Eucalyptus species (used by Sappi), Eucalyptus grandis and Eucalyptus urophylla and in

this way introduce hybrids which are more tolerant to the present conditions. Other species, such as

Corymbia hybrids which are tolerant to drier climates are also being considered.


66

P6

Evaluations of Mineral Elements and Total Protein content in the immature pods of different

Cowpea [Vigna unguiculata (L.) Walp.] Genotypes in South Africa

A.S. Gerrano , W.S. Jansen van Rensburg, P.O. Adebola, S.L. Venter

Agricultural Research Council – Roodeplaat Vegetable and Ornamental Plant Institute, Private Bag

X293, Pretoria 0001, South Africa

Cowpea is traditional and indigenous crop to the African continent and is grown for its young leaves,

succulent pod and grain in different countries of the world. It is the crop of rural Africa and are often

very high in vitamins and minerals. Improving cowpea will greatly improve diets for people affected by

hunger and malnutrition. To this end, a large number of cowpea germplasm collected from different

sources were maintained in the seed genebank of ARC-VOPI and are been evaluated. The objective

of this study was to quantify and determine the genetic variability of selected mineral elements and

total protein content in the immature pods of cowpea genotypes grown in South Africa. The

experiment consisted of twenty two different cowpea genotypes evaluated for two cropping seasons

in 2013 and 2014. The analysis of variance showed wide genetic differences in the mineral elements

and total protein content evaluated in the immature pods of cowpeas. The study revealed that there is

a wide genetic variability among the genotypes for the traits evaluated which can be exploited for use

in cowpea quality breeding programmes in South Africa.


67

P7

AN OVERVIEW OF THE APPLICATION OF MOLECULAR MARKERS AT THE AGRICULTURAL

RESEARCH COUNCIL – INSTITUTE FOR TROPICAL AND SUBTROPICAL CROPS

E. Hajari, A. Severn-Ellis, D. Nonyane and A. Sippel



The Agricultural Research Council - Institute for Tropical and Subtropical Crops (ARC-ITSC) in

Nelspruit has a vibrant research programme with plant breeding activities focused on fruit trees

including citrus (mandarins, sweet oranges, lemons, grapefruit and pummelos), litchi, mango, guava,

macadamia, pecan, granadilla, etc. Currently, cultivars grown locally are evaluated based on

morphological characteristics. However, there are some disadvantages with this method including the

fact it might be influenced by environmental conditions, which can hamper cultivar identification and

potentially lead to misidentifications. Molecular markers can provide a supplementary tool and has the

advantage of discriminating amongst cultivars quickly and efficiently without environmental influence.

A range of molecular markers are available, with microsatellite markers being the most popular. Over

the last few years at the ARC-ITSC, the potential of molecular markers, in particular Simple Sequence

Repeat (SSR) and Sequence-Related Amplified Polymorphism (SRAP) markers have been evaluated

using the available germplasm. To date, efforts have focused on investigating the genetic relatedness

between cultivars. This strategy has been tested using citrus, litchi and macadamia. The research

undertaken thus far has indicated the need to investigate the different types of molecular markers on

a case-by-case basis. In this context, it was found that SRAP markers were more informative than

SSR markers in evaluating the genetic diversity of litchi germplasm. This work is being extended by

testing additional, newly obtained germplasm from international collaborators. For macadamia

cultivars, the tested SSR and SRAP markers produced conflicting results which necessitates the

testing of newly available SSR markers that might be more informative. Work with citrus has revealed

that while the SSR markers can distinguish between the different citrus groups, determination of

specific cultivars within each group is problematic due to their genetic similarity. Investigations are

ongoing to overcome such difficulties.


68

P8

Artificial screening for cold tolerance of various Pinus species and hybrids

H. Ham1, F. Mabaso

1 and A. Nel

2

1Stellenbosch University, Private Bag X1, Stellenbosch, 7601

2Sappi Forests Sappi Forests Research, Planning and Nurseries, P.O. Box 1314, Howick, 3290,

South Africa

The South African forestry landscapes covers large variation in soils and climate, from cold and dry to

warm sub-tropical conditions, with summer and winter rainfall. A wide range of commercial Pinus

species are utilised by the forestry industry for these diverse growing conditions. The introductions of

many pests and diseases, such as Fusarium circinatum, have further challenged commercial Pinus

species. Traditional pines have been replaced by species and hybrids with increased tolerance to F.

circinatum during the past five to ten years. In many cases, the F. circinatum tolerant material has

lower levels of cold tolerance. Early screening techniques to determine frost tolerance of new

genotypes need to be developed to identify cold-tolerant material. The aim of this project is to develop

a reliable frost tolerance screening in vitro protocol to mimic in vivo conditions. In-field climatic data

was collected to construct a 24-hour model, mimicking in vivo (day and night) temperature fluctuations

to be simulated in vitro with electrolyte leakage and whole-tree freezing techniques. Rooted cuttings

from a range of genotypes supplied by Sappi were tested in vitro at different target temperatures to

determine their frost tolerance. These genotypes include pure species (P. patula, P. tecunumanii LE,

P. tecunumanii HE and P. oocarpa) and three hybrids (P. patula x tecunumanii LE, P. patula x

tecunumanii HE and P. patula x oocarpa). Preliminary in vivo results indicated that variation in levels

of frost tolerance among genotypes exists, and that these levels correspond to in-field survival after

frost events. Further experiments will determine the correlation between electrolyte leakage, whole-

plant freezing and field survival of planted trees.


69

P9

Identification of Crop Wild Relatives in South Africa.

M. Hamer1, P.O. Adebola

2, M.E. Dulloo

3, A.S. Gerrano

2, W.S. Jansen van Rensburg

2, S. Kell

4, R.R.

Klopper1, J. Magos Brehm

4, N.L. Muleleke

5, L. Nkuna

1, D.C. Raimondo

1, I. Thormann

3, T.T. Tjikana

5,

E. van Wyk1, S.L. Venter

2

1South African National Biodiversity Institute

2Agricultural Research Council

3Bioversity International

4University of Birmingham

5National Plant Genetic Resource Centre, Department of Agriculture, Forestry and Fishery

Crop wild relatives (CWR) are wild plant species which are genetically close to crops and have been

used since the beginning of agriculture to improvement. Their conservation, especially in their natural

surroundings, is crucial for agricultural research and development. However, CWR species are often

neglected by conservationists and thus threatened in the wild. Farmers and breeders are also often

unaware of the value of CWR. One of the aims of the SADC Crop Wild Relatives Project, co-funded

by the ACP-EU co-operation programme on science and technology is to identify and prioritize CWR

of food and fodder crops that grow in South Africa, in order to develop conservation plans and identify

traits for use in crop improvement.

A list of food and fodder crops was compiled which included 435 genera. The food and fodder list was

then matched to the South African National Plant Checklist (Germishuizen et al. 2006) and the Red

List of South African Plants online database (http://redlist.sanbi.org/) to identify wild relatives of these

crops that occur in South Africa. A total of 1609 native and introduced taxa (species, subspecies and

varieties) within 145 genera were included in the food and fodder CWR checklist for South Africa

These include CWR of cassava, cotton, groundnut, millet, mustard seed, rape seed, olive, sunflower,

sweet potato, wheat and yam.

Additional data required to prioritize 1609 taxa identified as CWR for conservation planning were

collated. The criteria for prioritization were the economic and socio-economic value of the related

crops, the CWR utilization potential for crop improvement using the gene pool and taxon group

concepts, threat status and rarity of the CWR and the occurrence status of taxon. Fifteen families, 33

genera and 263 species were included in the priority list. Nine of these are invasive species and 27

species are critically endangered.

http://redlist.sanbi.org/


70

P10

Applications of Flow Cytometry in Plant breeding Programmes of the Agricultural Research

Council's Institute for Tropical and Subtropical Crops

K. Hannweg and G. Visser



Since the first report on the use of flow cytometry in plant studies over three decades ago, a number

of applications of the technique have been developed, many of which can, and are, applied in plant

breeding programmes. Flow cytometry involves the analysis of fluorescence of single isolated nuclei

during their passage through a stream of liquid making it a precise method for analysis. The technique

is relatively fast, simple and cost-effective compared with conventional chromosome counting

methods. The ARC's Institute for Tropical and Subtropical Crops makes use of flow cytometry

analysis (FCM) to determine: (i) ploidy levels and to screen populations for mixoploids in breeding

programmes where chromosome doubling and controlled crosses are used; (ii) determine hybridity

based on DNA content; (iii) determine estimated DNA content for genomic size estimation for

genomic analysis and (iv) gender verification studies. FCM studies are carried out across a wide

range of commercial and indigenous plant species and a number of examples will be presented

P11

Distant hybridisation as a breeding technique to improve papaya

J. Husselman1, A. Van Biljon

2, Z. Bijzet

1 and A.D. Sippel

1

1Agricultural Research Council - Institute for Tropical and Subtropical Crops, Private Bag X11208,




In comparison to maize the genome of Caricaceae has a relative small genome of 372 Mbp which is

about the same as Citrus (382Mbp) which is eight times smaller than that of maize. The genome of

the Pine family is 56 times larger than Caricaceae and the Lily family is 322 times larger. The

Caricaceae family consists of six genera with papaya being the only species in the genus Carica.


71

Although numerous cultivars are available they tend to have related limitations which include, poor

tolerance to low temperatures, susceptibility to diseases, vigorous tall growing plants, wind sensitivity

and poor to no tolerance for water logging. Mutation breeding is of great use to a plant breeder with

limited genetic variation in a crop. Distant hybridization is another alternative method to introduce

unique characteristics into a crop with limited variation from another crop that is not closely related.

Little success has been achieved with this method as the probability of a successful cross and useful,

fertile progeny are very low. It is however an innovative technique and worth investigating.

The objective of the study was to evaluate the effectiveness of distant hybridisation as a breeding

technique to induce variation in the progeny of the selected papaya cultivars. Distant hybridization

involve the cross pollination of six papaya genotypes with three granadilla genotypes. Preliminary

investigations showed that the difference between the genetic content of papaya and the granadilla

could be detected through flow cytometry which might be useful to identify interspecies crosses. Only

one pollination combination rendered fruit with seed that could be germinated.

P12

Unlocking the potential of Crop Wild Relatives using predictive characterization.

W. Jansen van Rensburg1 , P.O. Adebola, M.E. Dulloo

2, A.S. Gerrano

1, M. Hamer

3, S. Kell

4, J.

Magos Brehm4, P. Moila

5, N.L. Muleleke

5, I. Thormann

2, T.T. Tjikana

5, S.L. Venter

1

1Agricultural Research Council – Roodeplaat Vegetable and Ornamental Plant Institute, Private Bag

X293, Pretoria 0001, South Africa

2Bioversity International

3South African National Biodiversity Institute

4University of Birmingham

5National Plant Genetic Resource Centre, Department of Agriculture, Forestry and Fishery

Wild species related to crops can be sources of novel genes for crop improvement. These crop wild

relatives (CWR) can especially be useful in a rapidly changing world facing climate change. However,

it is not always possible to characterize all available CWR accessions due to budget, human

resources and space constraints. Predictive characterization methods have been developed in order

to identify accessions that are likely to contain desired traits and thus allow targeted phenotypic

characterization and evaluation to be carried out on a selected subset of taxa. Predictive

characterization approaches involve GIS analysis of distribution, environmental and agro-ecological

data. One such approach is the ecogeographical filtering method that combines the spatial distribution


72

of the target taxon across ecogeographical regions of the territory with the identification of

environmental profiles that are likely to impose selection pressure for the adaptive trait investigated, to

filter occurrence records. In the context of the SADC Crop Wild Relatives project we used the

ecogeographical filtering method to search for Vigna CWR populations likely to harbour genetic

diversity for heat and drought tolerance. Occurrence records for the Vigna wild relatives were

obtained from SANBI and complemented with freshly collected data obtained from field trips.

Populations that occur where environmental conditions are conducive for finding the specific traits are

found were identified. These populations can then be targeted for collection, conservation and

incorporated in the Vigna breeding programme currently undertaken at ARC.

P13

MOLECULAR FINGERPRINTING AND CHARACTERISATION OF ARC’S PEACH COLLECTIONS

L. Kwalimba1, K.R. Tobutt

1, R. Roodt-Wilding

2, W. Pieterse

1 and C. Hörstmann

1


South Africa


Peaches (Prunus persica) are the fifth most commercially important deciduous fruit in South Africa;

the industry is worth R800 million and employs 10, 000 people. The Cultivar Development Division of

the Agricultural Research Council (ARC) institute at Infruitec-Nietvoorbij has been the primary source

of improved peach cultivars since 1937. The germplasm collection for the breeding programme, which

is based at Bien Donne research farm in Groot Drakenstein, includes cultivars, selections, accessions

of related Prunus species such as almond, and interspecific hybrids and is complemented by the

national reference collection of peach and almond cultivars. The advent of molecular markers is

allowing the fingerprinting of these genetic resources with microsatellites markers. Nine microsatellite

markers were optimised in three multiplexes and used to fingerprint 140 peaches, 72 nectarines, 20

almonds, 9 peach hybrids and 2 interspecific hybrids. In addition, the collections have been

molecularly characterised with respect to the endopolygalacturonase (endoPG) genes responsible for

the freestone and melting traits in peach, using endoPG4 and endoPG5 markers and visualising the

products on agarose gels to deduce genotypes. A new set of markers, endoPG6 and endoPG1-SSR,

is still being optimised which should allow more efficient genotyping as the amplicons can be

genotyped through automated sizing of PCR products.


73

P14

COMBINING ABILITY OF LOCAL AND EXOTIC MAIZE (ZEA MAYS L.) INBRED LINES FOR

GRAIN YIELD UNDER LOW NITROGEN STRESS

P. Makhumbila , K. Mashingaidze1 and E.T. Gwata

2

1ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom, 2520

2University of Venda, Private Bag X5050, Thohoyandou, 0950

Soils in South Africa are inherently low in nitrogen (N) and maize (Zea mays L.) production in the

smallholder farming sector is low due to a lack of sufficient fertilizer use. The main objective of the

study was to evaluate maize inbred lines for combining ability for grain yield under low N stress. The

North Carolina-II design was used to develop hybrids using eighteen local inbred lines from the

Agricultural Research Council and thirty exotic inbred lines from International Maize and Wheat

Improvement Center, and International Institute of Tropical Agriculture. One hundred and three

hybrids, and three checks were evaluated under low N and optimum in 2014/15 summer season. An

(0, 1) alpha lattice design replicated twice was used. Low N stress trials were planted in

Potchefstroom and Taung while optimum N trials were planted in Cedara and Potchefstroom.

Recommended agronomic practices were carried out. Low N stress trials were planted without

nitrogenous fertilizer. Data were subjected to analysis of variance using GENSTAT. Specific (SCA)

and general combining ability (GCA) were estimated using AGD-R software. There were significant

differences for grain yield among environments and sites. Hybrids with the highest SCA for grain yield

across low N sites were L8/CB232 and L8/CML545. Across optimum conditions, hybrid L1/CML489

and CHECK1 had the highest SCA estimates for yield. Across low N sites inbred lines L8, L17, L12,

L20 and L22 had the highest GCA estimates as females while T11162W, TZEI56, CML538, CB255

and CML489 had the highest estimates as males. Across optimum sites L14, L12, L1, L4 and L16 had

high GCA estimates as females. Inbred lines with the highest GCA as males across optimum sites

were CML538, CML489, TZEI63, RO549W and T1162W. Hybrids with high SCA estimates can be

evaluated further and considered for release. Inbred lines with high GCA estimates can be used as

testers for low N tolerance breeding.


74

P15

THE EFFECT OF LOWER SODIUM CHLORIDE LEVELS ON BREAD QUALITY

A.F. Malan and C.W. Miles

Agricultural Research Council-Small Grain Institute, Private Bag X29, Bethlehem, 9700, South Africa

The Heart and Stroke Foundation of South Africa implied that 80% of cardiovascular diseases could

be prevented by adapting a lifestyle which include a reduction in sodium chloride. Dr Vash Mungal-

Singh (CEO, Heart and Stroke Foundation South Africa) stated bread to be the main culprit, since it is

consumed daily by most of the population (http://heartfoundation.co.za/media-releases/salt-is-killing-

South-Africans-and-it-is-time-to-take-action). South African Government therefore published a list of

food products that needed less sodium chloride and implementation of the first phase being required

by June 30th2016. A second adaptation regarding sodium chloride levels needs to be implemented

three years later (Government Gazette, March 2013).

Sodium chloride plays a major role in bread production since it acts as a preservative, it contributes to

flavour, it plays a role in the development of the gluten network by strengthening, tightening and

compacting the dough and it plays a role in the browning process of the bread

(http://www.sustainweb.org/realbread/salt-in-bread).

The South-African bread-making industry has strict criteria regarding the processing quality of South-

African wheat. High loaf volumes, smooth texture, attractive colour, acceptable mixing times and shelf

life are important factors and it is of utmost importance that these factors not be influenced by lower

sodium chloride levels, due to financial implications for the bread-making industry. A basic recipe

containing only bread wheat flour (at two different protein content levels), water, sodium chloride

(1.50%, 1.00% and 0.95%), sugar, compressed yeast and fat were tested and evaluated for loaf

volume, texture, colour, shelf life and mixing time. The different sodium chloride content levels did not

affect these parameters. A tasting panel also confirmed that the loaves of bread containing lower

sodium chloride levels, tasted acceptable and if implementation of the lower sodium chloride levels

are done over a period of time, consumers will not taste the difference.

http://heartfoundation.co.za/media-releases/salt-is-killing-South-Africans-and-it-is-time-to-take-action

http://heartfoundation.co.za/media-releases/salt-is-killing-South-Africans-and-it-is-time-to-take-action

http://www.sustainweb.org/realbread/salt-in-bread


75

P16

Heritability and genetic gain for grain yield and path coefficient analysis of some agronomic

traits in early-maturing maize hybrids

S. Maphumulo1 , J. Derera

1 and F. Qwabe

2

1University of KwaZulu-Natal, Private Bag X01, Scottsville 3209

2KZN Department of Agriculture and Rural Development

Breeders face serious challenges in breeding early-maturing maize hybrids which are required by

farmers in marginal environments. The objectives of the study were to determine the genetic gain for

breeding for high yield, and investigate levels of genetic variation, heritability and associations

between grain yield and secondary traits in early maturing hybrids. Fifty maize hybrids were evaluated

at three sites in KwaZulu-Natal, South Africa in a 5 x 10 α-lattice design with two replications. Genetic

gain for grain yield of 18% was reflected by the top five experimental hybrids over the population

mean, indicating a significant improvement. One of the top five hybrids 14XH293 was early-maturing

and non-significantly different from other three top-yielding intermediate to late hybrids but was as

early as the early commercial checks. Significant genetic variation for grain yield, plant and ear height,

grain moisture, days to anthesis and silking, ear position, ear prolificacy, number of ears and

anthesis-silking interval was observed, indicating opportunities for further improvement of the hybrids.

Grain yield was highly heritable (75%) but heritability ranged from low (3%) to high (79%) for

secondary traits. Both correlation (P≤0.001) and regression (P≤0.001) indicated that ear prolificacy is

the highest contributor to grain yield improvement. Furthermore, ear prolificacy displayed the major

direct effects on yield that was greater than its correlation with yield, indicating that selection for this

trait would indirectly improve grain yield of early-maturing maize hybrids.


76

P17

Identification of genes controlling dwarf trait in apple (Malus pumila Mill.).

Z. Mbulawa1, J. Kriel,

1 A. van der Merwe

2 and K. Tobutt

1


South Africa


The genetic determination of many growth habit traits in apple is still poorly understood. Various

genes for dwarf growth have been reported in the literature but few, if any, have been mapped and

characterised. An apple progeny derived from the cross ‘McIntosh x M9’ segregating for a dwarf trait

has been raised at the Agricultural Research Council (ARC) Infruitec-Nietvoorbij’s Bien Donné

Research Farm. Preliminary phenotypic assessment revealed segregation ratios of approximately 9:7

for normal versus crinkle dwarf seedlings which is consistent with control by two complementary

genes. Mapping of two epistatic genes segregating simultaneously may not be straightforward.

Therefore, a supplementary apple progeny derived from the cross ‘McIntosh x M1’ which segregates

in a 3:1 ratio for normal versus crinkle dwarf, presumably at just one of the two loci, has been chosen

initially for mapping. This progeny is being genotyped with evenly spaced microsatellite markers

selected from across the apple genome. Co-segregation analysis will be used to map the gene and to

identify potential candidate genes. A transcriptomic approach will also be pursued in parallel to

determine genes expressed differentially between the contrasting phenotypes. Other progenies

derived from ‘McIntosh’ are being raised with the view to mapping the second gene. This study should

clarify the molecular genetics and the mechanism behind these dwarf traits in apple. Furthermore,

studying and tracing genes in relevant pedigrees will help avoid raising progenies segregating for

dwarf types in the future.


77

P18

Morphological diversity of selected South African sorghum [Sorghum bicolor (L.) Moench]

genotypes

A. Mofokeng1, H. Shimelis

2, M.D. Laing

2 and N.G. Shargie

1

1Agricultural Research Council, Grain Crops Institute, Private Bag X 1251, Potchefstroom, 2520

2African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences,

University of KwaZulu-Natal, Private Bag X 01, Scottsville, 3209

The success of any breeding or genetic conservation programme relates to the amount and

distribution of genetic variation present in the gene pool. Knowledge of the genetic diversity among

sorghum genotypes is essential for parent selection with current and future improvement programmes

in order to ensure crop improvement. The objective of this study was to assess the level of genetic

diversity present among some South African sorghum genotypes using agro-morphological traits.

Ninety eight sorghum accessions obtained from the Department of Agriculture Forestry and Fisheries,

African Centre for Crop Improvement and Agricultural Research Council-Grain Crops Institute were

phenotyped during 2012 at two sites, Makhathini Flats and Burgershall in KwaZulu-Natal and

Mpumalanga provinces, respectively. Experiments were laid out using an alpha lattice design with

three replications. Data on eight quantitative and six qualitative traits were collected and subjected to

principal component (PC) hierarchal cluster and multivariate analyses and a dendrogram constructed

using the Unweighted Pair Group Method with Arithmetic Mean. The principal component analysis

revealed three important PCs that contributed to the total variation of 88.9% observed among

genotypes across locations. PC1, PC2 and PC3 contributed to 46.69, 30.74, and 11.45% of the total

variation, respectively. A dendrogram revealed three main clusters of genotypes. The grouping of the

sorghum genotypes was not based on source of collection. The most diverse accessions identified

were MP 4277, EC 2934, KZ 5097, FS 4909, and LP 4303 which will accordingly be very useful within

breeding programmes.


78

P19

Improved resistance to Fusarium ear rot and fumonisin contamination in F1 maize hybrids.

N. Netshifhefhe1, B. Flett

2, S. Okoth

3, A. Viljoen

1 and L. Rose

1

1Department of Plant Pathology, Stellenbosch University, South Africa. , Private Bag X1,

Stellenbosch, 7601

2Agricultural Research Council - Grain Crops Institute, Potchefstroom, South Africa

3School of Biological Sciences, University of Nairobi, Kenya.

Fusarium ear rot (FER) and fumonisin contamination of maize, caused by Fusarium verticillioides, can

result in crop yield reduction, lower grain quality and mycotoxicoses of humans and livestock. An

effective way to manage this fungus is through the development of maize cultivars resistant to FER

and fumonisin accumulation. Currently, no resistant maize cultivars are available to farmers.

Therefore the objective of this study was to evaluate maize inbred lines and their resultant F1 hybrids

for resistance to FER and fumonisin contamination. South African maize inbred lines resistant

(CML444) and susceptible (R119W) to F. verticillioides and fumonisin accumulation were crossed

with two Kenyan inbred lines (CKL05015 and CML495), previously characterised as resistant to

Aspergillus flavus and aflatoxin accumulation, and resulted in six hybrids. The hybrids and parental

lines were planted in field trials at Potchefstroom, Vaalharts and Makhatini. All trials were artificially

inoculated with F. verticillioides and disease development, fungal colonisation and total fumonisin

contamination was determined. The F1 hybrid resulting from a resistant x susceptible cross, CML444

x R119W, was the best performing genotype across all localities for fungal colonisation and fumonisin

accumulation. This hybrid also differed significantly from both parental lines (P = 0.05). The least FER

severity, across localities, was observed on CML495 x CKL05015. The F1 hybrid, CKL05015 x

CML444, accumulated the least fungal and fumonisin contamination in Makhatini and Vaalharts which

were ideal environments for these evaluations as determined by GGE biplot analysis. The F1

CML495 x CML444 and CKL05015xR119W hybrids were the least resistant to F. verticillioides and

fumonisin accumulation and were not significantly different (P = 0.05) from the susceptible inbred

R119W. The employment of resistant maize plants would help farmers acquire good crop quality and

minimize mycotoxin contamination.


79

P20

CHARACTERIZATION OF SWEETPOTATO [Ipomoea Batatas (L.) Lam] GERMPLASM USING

MORPHOLOGICAL TRAITS AND PROTEIN CONTENT

S. Naidoo1, S. Laurie

1, H. Shimelis

2 and M. Laing

2

1Agricultural Research Council, Vegetable and Ornamental Plants (ARC-VOP), Private bag X293,

Pretoria, 0001

2School of Agricultural, Earth and Environmental Sciences, University of Kwa-Zulu Natal, Private Bag

X01, Scottsville 3201, Pietermaritzburg, South Africa

Bio-fortification of staple crops through plant breeding is a cheaper and sustainable approach to avail

macro- and micronutrients to resource poor households. Sweetpotato (2n=6x=90) is one of the major

staple crops contributing to food security in the developing countries. Interest in growing sweetpotato

has grown tremendously during the past three decades since sweetpotato roots and leaves combine

rich nutritional content important for the human health. In order to breed for sweetpotato varieties with

higher nutritional content, knowledge on the magnitude of protein content, flowering ability, and yield

potential present among sweetpotato germplasm collection is a pre-requisite. The aim of the current

study was to assess the genetic diversity among selected ARC sweetpotato germplasm for protein

content, and other important morphological and agronomical characteristics. A trial containing 73

genotypes was established using a randomized complete block design with two replicates. Data were

collected on root shape, colour, defects, yield and root quality. Protein content was determined using

the Near Infrared Reflectance Spectrophotometer. Results shown marked variability among tested

germplasm for all traits. Root yield varied from 0 to 2.46 kg/plant with a mean of 0.82 kg/plant. The

protein content varied from 0.45% DM (dry mass) in variety ‘Maqua’ to 4.18% DM in clone ‘1984-41-

12’. About 65% of the tested clones did not flower, 15% produced only a few flowers, 15% had

intermediate number of flowers and 5% flowered abundantly. Overall, 14 clones were selected for

further quality breeding. Clones ‘IIAM 10’, ‘1988-20-1’ and ‘1986-35-1’ with root yields of 1.95

kg/plant, 1.42 kg/plant, 0.92 kg/plant, respectively were promising due to high to intermediate root

protein content, and flowering ability. These clones were selected as parents for designed crosses in

the improvement of sweetpotato for root protein content and other desired agronomic attributes.


80

P21

Evaluation of Pod Shattering in a Distinct Soybean F2 Plant Population

K.M. Nevhudzholi1, E.T. Gwata

1. and G.R.A. Mchau

2

1Department of Plant Production, University of Venda, Private Bag X5050, Thohoyandou 0920, South

Africa.

2Department of Horticulture, University of Venda, Private. Bag X5050, Thohoyandou 0920, South

Africa.

Soybean (Glycine max) is an important grain legume world-wide. It is used for human consumption

and livestock feeds. The crop also contributes significantly to soil fertility through symbiotic fixation of

nitrogen in root nodules. Tropical types of soybean that require no artificial seed inoculation at

planting in order to attain optimum grain yield are desirable particularly in smallholder cropping

systems in many parts of Africa. However, these tropical types are generally susceptible to pod

shattering resulting in considerable losses in grain yield. This study examined the genetic control of

pod shattering in an F2 segregating soybean population derived from a tropical (shattering type) x

non-shattering (non-tropical type). The successful crosses were confirmed using morphological and

physiological markers such as flower colour and hylum colour under greenhouse conditions. The oven

method was used for determining the shattering scores. The data sets were subjected to chi-square

tests for goodness-of-fit of four genetic models (3:1; 9:7; 13:3 15:1). The data fitted a 9:7 ratio

indicating that the trait was governed by complete dominance at both gene pairs, but either recessive

homozygote is epistatic to the effects of the other gene. The large variance in the plant population

suggested the potential of selecting for pod shattering in early generations of soybean.


81

P22

Characterizing South African historic wheat cultivars for seedling stem rust resistance

P. Ntshakaza1,2

, T.J. Tsilo1, H. Shimelis

2 and T. Terefe

1

1Agricultural Research Council-Small Grain Institute, Private Bag X29, Bethlehem, 9700, South Africa

2African Center for Crop Improvement, University of KwaZulu-Natal, Private Bag X01, Scottsville,


Stem rust is a historically and economically important wheat disease which can result in severe yield

losses. Wheat is currently the second most important cultivated grain in South Africa. Historically,

annual wheat production has decreased due to unfavourable abiotic and biotic stresses, such as stem

rust caused by the pathogen Puccinia graminis Pers.f.sp.Tritici Eriks & Henn. Emergence of new

virulent races has led to a search for new sources of rust resistance to be developed and deployed for

effective control. The aim of this study was to characterize South African historic wheat cultivars for

the presence of stem rust resistance in the seedling stage. A total of 260 South African historic wheat

cultivars were evaluated for seedling resistance by observing their infection type response to four

stem rust races at seedling growth stage. The results confirm that historic cultivars contain important

genes, which can be transferred through gene pyramiding, into lines with other important traits. The

information about genes present in South African historic wheat cultivars is limited, thus the outcomes

of the study will assist in selecting historic cultivars to use as sources of stem rust resistance.


82

P24

QTL validation of marker-trait associations for stem rust resistance in a diverse panel of

African wheat

R. Prins 1,2,‡

, S. Dreisigacker3,‡;, Z. Pretorius

2, E. Wessels

1, H. van Schalkwyk

1,2, C. Smit

1, C.

Bender2, D. Singh

4, L.A. Boyd

5,6

‡These authors contributed equally to the work


2Department of Plant Sciences, University of the Free State, Bloemfontein 9300, South Africa

3International Maize and Wheat Improvement Center (CIMMYT), Apdo, Postal 6-641, 06600 Mexico

DF, Mexico

4University of Sydney, Plant Breeding Institute Cobbitty, Private Bag 4011, Narellan, NSW 2567,

Australia

5National Institute of Agricultural Botany, Huntingdon Road, Cambridge, CB3 0LE, UK

6Department of Life and Medical Sciences, University of Hertfordshire, Hatfield, Hertfordshire, AL10

9AB, UK

A genome-wide association study (GWAS) was undertaken in a collection of wheat genotypes

gathered from across Africa to identify stem rust resistance effective against the Ug99 race group of

Puccinia graminis f. sp. tritici. Stem rust phenotypic data were collected from field trials carried out

across two seasons in Kenya in 2009 and in South Africa in 2011, and from a glasshouse seedling

test in South Africa in 2010. Genotyping with DArT markers generated 2185 polymorphic loci, of

which 1476 were mapped. Twenty-one SSR markers reported to be linked to known Sr genes were

also used. The rate of linkage disequilibrium decay within the African wheat collection extended over

a genetic distance of 5 cM. Population structure analyses identified the Sudanese wheat lines as a

distinct group, while with the remaining wheat lines groupings based on origin indicated some overlap

in the genetic structure. Following GWAS two lines (W1406 and W6979) displaying multi-QTL adult

plant stem rust resistance were selected to generate bi-parental mapping populations for validation

purposes. Subsequent mapping and QTL analysis in these populations reduced the number of

significant marker-trait associations from the GWAS’ prediction, substantially


83

P25

DNA FINGERPRINTING OF FRUIT CROPS AT THE ARC

S. Safodien and K. Tobutt


South Africa

The ARC Infruitec-Nietvoorbij offers DNA fingerprinting as a diagnostic service to growers, nurseries

and plant breeders. We are regularly approached to establish the authenticity of plant material,

especially of fruit crops, and to determine trueness-to-type of scion varieties and rootstocks. DNA

fingerprinting can help prevent the fraudulent commerce of plant material and protect plant breeder’s

rights and sole grower rights. It can also be used to ensure growers are provided with correct

material. Our DNA fingerprinting diagnostic service is now based on the use of standard sets of

microsatellites to check identities and deals not only with apple, pear, apricot, plum, peach and grape,

but also fig, date and olive. We have had a lot of experience fingerprinting to check the authenticity of

our genebank collections and to provide ‘baseline’ data prior to future propagation. We are thus

developing a substantial database of reference fingerprints. Colleagues are also developing a range

of gene-specific or functional markers, for example, for incompatibility in pome and stone-fruit (S-

alleles), ethylene production and fruit ripening in apple (ACS1), and flesh colour in peach (CCDO).

Such markers can be used for characterising cultivars with respect to these traits. These recent

developments allow the ARC to deliver additional services, enhancing what the DNA fingerprinting

diagnostic service can offer the fruit industry


84

P26

Classification of ARC Maize (Zea Mays L.) Inbred Lines into CIMMYT A and B Heterotic Pools

S.F. Shandu1, K. Mashingaidze and J. Derera

2

1ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom 2520

2University of KwaZulu-Natal, Private Bag X01, Scottsville 3209

Successful development of improved maize varieties requires a well-arranged germplasm which

provides maximum heterosis; knowledge of heterotic groups and heterotic patterns facilitate the

process. The objective of the study was to classify ARC maize inbred lines following the CIMMYT A

and B heterotic pools. Thirty-eight maize inbred lines from seven known ARC heterotic groups were

crossed to four testers representing heterotic group A (B73 and CML312) and B (MO17 and

CML444). Hybrids were evaluated at Potchefstroom and Cedara in a (0, 1) alpha lattice design.

Classification was based on the specific combining ability (SCA) effects for grain yield; where positive

SCA effects with one tester indicate that lines belong to the opposite heterotic group and negative

SCA indicate similar heterotic group. The AGD-R CIMMYT software was used for analyses. Inbred

lines were allocated into heterotic group A, some to B, and others to both A and B. Lines allocated to

AB group showed positive SCA with both testers. Classification of most inbred lines corresponded

with their pedigrees. However, because inbred lines used were obtained from known heterotic groups,

there was a distortion in the classification where inbred lines from the same group were classified

differently. This could be due to the interaction between a specific tester and a specific inbred and

therefore differences in groupings. Regardless of the differences in the origin of testers (CIMMYT and

USA) used, classification by either heterotic group A or B was consistent, confirming that CML312

(CIMMYT) and B73 (USA) belong to group A, and also CML444 (CIMMYT) and MO17 (USA) belong

to group B. Classification of a few lines into AB group suggests that yield data alone might not be

sufficient for full classification; molecular data may also be crucial. This classification will be useful in

improving elite lines primarily for abiotic stresses.


85

P27

Mapping the Russian wheat aphid (Diuraphis noxia) resistance gene (Dn2401) on the 7DS

chromosome of wheat (Triticum aestivum L.)

T.N. Sikhakhane 1, 2

, V. Tolmay1 and T.J. Tsilo

1

1Agricultural Research Council, Small Grain Institute, Bethlehem, South Africa

2Department of Life and Consumer Sciences, University of South Africa, Pretoria, South Africa

Russian wheat aphids (RWA), Diuraphis noxia (Kurdjumov), are important pests of wheat (Triticum

aestivum L.), barley (Hordeum vulgare L.) and other small grains. They feed from the plants phloem

and in-turn, result in major yield and economic losses. In South Africa, there are currently four known

aphid biotypes, namely, RWASA1, RWASA2, RWASA3 and RWASA4. Several methods have been

used to control the aphids, including, insecticide application, bio-control agents and producing

resistant cultivars. Due to the negative environmental impacts of insecticides, host plant resistance

has been a widely used and efficient method for controlling or defeating aphid infestation. Several D.

noxia resistance (Dn) genes have been produced and deployed, each being effective against one or

more of the biotypes. The wheat accession CItr2401 has a resistance gene, Dn2401, which is a

valuable source of resistance, still being effective against all the pest biotypes in the world, including

those in South Africa. The resistance mechanism is effective but the emergence of new biotypes

poses a challenge in the development of RWA resistant cultivars. In the proposed study, a BC5F5

near isogenic lines (NILs) population of wheat consisting of 127 lines will be used as the mapping

population. The mapping population was created from a cross between the resistant CItr2401 and

susceptible Kavkaz cultivars. For the purpose of this abstract, only the RWA screening results

(phenotypic tests) will be presented. RWA screening was carried out in the greenhouse on the 127

lines and 5 (known resistant and susceptible) controls for the 4 biotypes. Single plants were rated with

a 1-10 point damage rating scale, which is based on visible leaf chlorosis and leaf rolling. The plants

were considered resistant (R) if the damage rating was 1-6 and susceptible (S) if the damage rating

was 7-10. Infestations of RWASA1, RWASA2, RWASA3 and RWASA4 showed 2%, 3%, 16% and

20% resistance phenotypes in the wheat entries, respectively. The results show that the four South

African biotypes differ in virulence from one another and that the resistance gene (Dn2401) is indeed

present in the mapping population as resistance phenotypes were observed. Further molecular

studies will be conducted on those plants that displayed resistance. In South Africa, the Dn2401 gene

has not yet been mapped, thus the aim of this research study is to identify the markers closely-linked

to the gene and to map the gene on the 7DS chromosome of bread wheat.


86

P28

Genetic analysis of stripe rust resistance in the wheat line NRSPan4

C. Smit1, Z.A. Pretorius

2, E. Wessels

1, C.M. Bender

2, V. Knight

3, W.H.P. Boshoff

3 and R. Prins

1,2


2Department of Plant Sciences, University of the Free State

3Pannar Seed Ltd

Large investments have recently been made to advance resistance breeding to wheat stripe rust,

caused by Puccinia striiformis, in South Africa. A number of adult plant resistance QTL have been

identified and successfully incorporated into South African wheat breeding programs through marker

assisted selection (MAS) in the molecular marker service laboratory (MSL) at CenGen. A potential

new source of resistance was identified in a CIMMYT line, renamed NSRPan4. The importance of

expanding the number of resistance resources available to breeders prompted the development of a

recombinant inbred line (RIL) mapping population by crossing NSRPan4 with Avocet S to unravel the

genetics of the resistance. Field data of F2 (χ²15:1 = 1.187, p = 0.276) and BC1F2 (χ²3:1 = 0.297, p =

0.586) segregating material obtained during construction of the RILs showed a significant fit for a two-

gene model. A QTL mapping effort identified two stripe rust resistance genes/QTL on chromosomes

2A and 2B. The QTL on 2A accounted for up to 83% of the variance observed in leaf area infected

(LAI) and up to 92% of the variance in reaction type (RT) and is most probably a seedling resistance

gene. The QTL on 2B had a smaller effect, contributing 13% of the LAI and 14% of RT. Leaf damage

was also assessed with a Greenseeker® crop sensor and the QTL on 2A and 2B respectively

explained 19% and 6% of the variance. The NSRPan4-derived stripe rust resistance genes/QTL are

already being applied in MAS in MSL.


87

P29

OPTIMAL POPULATION SIZE WHEN PRE-BREEDING FOR MULTIPLE PEST RESISTANCE

BREAD WHEAT LINES

S.L. Sydenham and V.L. Tolmay

ARC-Small Grain Institute, Private Bag X29, Bethlehem 9700, South Africa

Currently, wheat production has been on the steady decline in South Africa. However, bread wheat

(Triticum aestivum L.) still remains an important staple food that contributes substantially to feeding

the world’s population. Wheat is one of the most adaptable crops planted over vastly different

environmental regions all over the world. This exposes wheat to a large number of pests and

diseases, such as Russian wheat aphid and cereal rusts. These pests can occur singularly or

simultaneously in a single season which can have a significant impact on wheat production. Breeding

for resistance to these pests/diseases is the most effective and environmentally responsible way to

manage them. However, selection for one or two of these in a single season phenotypically is not

feasible. Furthermore, there is a need for the responsible deployment of genes found within landraces

or lines that may include other possible negative quality characteristics that breeders would like to

ovoid. Pre-breeding for these desirable traits together with gene stewardship is there for a critical to

ensure that wheat breeders have high potential lines with durable resistance which can be

incorporated into their breeding programmes without introducing negative traits. This poster discusses

the approach, results and outcomes of a pre-breeding programme targeting multiple combinations of

Russian wheat aphid (RWA) resistance, Leaf, Stripe and stem rust resistance for certain South

African and international production regions. A focus is placed on the size of the starting population

when selecting and targeting different resistance sources. What is too big or too small, what is

optimal? Analysis of the successful selection pressure achieved when comparing different starting

population sizes when using phenotypic selection in combination with simultaneous marker-assisted

selection. This is related to the end number of Pre-breeding lines selected for possible release per

combination.


88

P30

Collection and Preliminary characterization of the Spider Plant (Cleome gynandra) germplasm

in Limpopo (South Africa).

F. Thovhogi1, E.T. Gwata

1 and G.R.A Mchau

2

1Department of Horticulture, University of Venda, Private Bag X5050, Thohoyandou 0920, South

Africa.

2Department of Plant Production, University of Venda, Private Bag X5050, Thohoyandou 0920, South

Africa.

The spider plant (Cleome gynandra) is an important leafy vegetable that grows naturally in many parts

of the world including the Limpopo Province (South Africa). The leaves are highly nutritious and are

used mainly for human consumption. The leaves can be used also for medicinal and insecticidal

purposes. In southern Africa, young tender shoots that are preferred by end-users, are boiled and

consumed as a side-dish. Alternatively, the leaves are dried for consumption during the off-season

period. In Limpopo Province, the spider plant (also called Cleome or African cabbage) is popular

among the rural communities in particular. However, there are no improved cultivars of this vegetable

that can be produced on a commercial scale. This study was designed to initiate the assembly and

characterization of local germplasm of Cleome. Germplasm collection missions were conducted in

north-eastern Limpopo Province during the 2012/2013 cropping season. Based on distinct phenotypic

characters, seed of 18 accessions was collected from the region and subsequently multiplied in the

greenhouse for purification and characterization. The germplasm showed variability in duration to

flowering, stem colour, petiole colour as well as seed attributes. Subsequent phases of the study

intend to determine (i) the genetic control of the key nutritional attributes (amino acids, vitamins and

minerals) in order to enable efficient manipulation of the traits in a cleome genetic enhancement

program and (ii) the micro-propagation potential of Cleome in order to optimize its production during

the off-season.


89

P31

PRE-BREEDING BREAD WHEAT LINES WITH RUSSIAN WHEAT APHID RESISTANCE

V. Tolmay , A. Barnard and S. Sydenham

ARC-Small Grain Institute, Private Bag X29, Bethlehem 9700, South Africa

Bread wheat (Triticum aestivum L.) is a staple food that contributes substantially to feeding the

world’s population. Genetically wheat is complex with different species containing multiple copies of

the basic 1x chromosome number of seven, and bread wheat specifically is a hexaploid (2n=2x=42).

This makes it a very adaptable crop and it is grown in a large variety of environmental conditions from

low to very high yield potential regions. This wide adaptation exposes it to a large number of biotic

and abiotic stresses which can negatively influence production. Breeding for resistance to these

stresses is an effective and environmentally responsible way to manage them, but not necessarily an

easy task given the complex nature of the crop itself. Furthermore, many useful genes encoding

useful resistance are found in germplasm collections, within landraces or lines that include other

deleterious characteristics that breeders are keen to avoid introducing to their breeding programmes.

Pre-breeding for desirable traits is therefor a crucial activity to ensure that wheat breeders have high

potential lines containing traits of interest which can be incorporated into their programmes without

introducing negative traits. This poster discusses the pre-breeding programme for Russian wheat

aphid (RWA) resistance in South Africa and highlights the secondary resistance traits like Stripe rust

(caused by Puccinia striiformis) resistance, Leaf rust (caused by Puccinia triticina f. sp. tritici), Stem

rust (caused by Puccinia graminis f.sp. tritici) resistance, and resistance to pre-harvest sprouting that

add value to RWA resistant lines being developed for release to breeders.


90

P32

Association of grain yield, proline and stress tolerance indexes in selection for drought stress

tolerance in soybean

R. Van der Merwe1, O.J. Mwenye

1 and L. Van Rensburg

2

1Department of Plant Sciences, University of the Free State, Bloemfontein, South Africa

2Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, South

Africa

Drought tolerance is a complex quantitative trait involving interactions of many metabolic pathways. In

the absence of an understanding of the special mechanisms of tolerance the quantification of drought

tolerance should be based on grain yield under dry conditions. The objectives of this study were to 1)

evaluate the ability of several selection indices to identify drought tolerant genotypes and 2) associate

indices with yield and proline accumulation under stress and non-stress conditions. Four genotypes

were evaluated for yield under water-limited-induced-stress (Ys) and non-stress (Yp) conditions in

weighing lysimeter units using a RCBD. Drought tolerance indexes including mean productivity (MP),

stress susceptibility index (SSI), stress tolerance (TOL), stress tolerance index (STI), geometric mean

productivity (GMP), yield index (YI) and yield stability index (YSI) were used. Significant and positive

associations were observed among yield, proline accumulation and the drought tolerance indexes.

Principal component analysis confirmed the data structure and relations of yield, proline and the

drought tolerant indexes. PC-1 was related to grain yield (Yp), GMP, MP and TOL while PC-2 was

mostly explained by TOL, Ys, GMP and MP. The most prominent associations were among TOL,

proline under stress and relative change in proline, and between STI and MP. The association of

yield, proline accumulation and the drought tolerant indexes suggested that these indexes are

effective in identifying high yielding and tolerant genotypes under stress and non-stress conditions.

The correlation matrix and PCA analysis gave complementary information and such knowledge could

assist breeders in making selection decisions.


91

P33

Yield potential and stability of vegetable-type soybean genotypes

R. Van der Merwe1, A. Smit

2, M. Smit

2, M.T. Labuschagne

1

1Department of Plant Sciences, University of the Free State, Bloemfontein, South Africa

2Edamame Development Program, Hillcrest, KwaZulu-Natal, South Africa

Vegetable-type soybean, has recently been introduced to South Africa as a supplementary high

quality protein source for vegetarians as well as to serve as a new nutritional crop for rural community

gardens projects. However, lack of adapted cultivars is one of the major factors limiting its commercial

production in the country. The aims of this study were to evaluate and identify genotypes for potential

production in South Africa and to identify suitable parents that could be used in the breeding

programme. A two-year study (2013/2014-2014/2015) was performed to evaluate 16 non-genetically

modified cultivars, across five locations for various traits including days to flowering and maturity,

plant height, pod height, number of nodes per plant, number of branches per plant, 100-seed weight

and seed yield. Combined analysis of variance indicated highly significant (p < 0.01) variation among

genotypes for all traits analysed. Genotypes showed large variation in days to flowering (44-75 days)

and maturity (100-167 days). Grain yield ranged from 1.35-2.34 t ha-1

with 100-seed weight ranging

from 16-40 g. Highly significant genotype x environment effects were observed for grain yield and as

a result multivariate analysis (AMMI) was done. AMMI biplots revealed that Winterton was the most

stable location for grain yield. Of the top three yielding genotypes AGS354, AGS418 and AGS352

only AGS418 showed acceptable adaptability across locations and seasons. From this study,

potential genotypes have been identified that could be utilised as a source of traits in the vegetable-

type soybean breeding programme.


92

P34

Guava Breeding in South Africa: challenges and future prospects

S. Willemse , C.F. Human and A.D. Sippel

ARC-Institute for Tropical and Subtropical Crops, Private Bag X11208, Nelspruit 1200, South Africa

Guava cultivation in South Africa dates back to 1688 when the first guava trees was brought to the

country from Madeira by Jan van Riebeeck. As there were no other guavas in the country at that

stage, the trees propagated by means of seed remained true to type. Some of the old trees can still

be found today in the Paarl region and in gardens at Stellenbosch. Different types of guavas were

introduced into the Cape between 1830 and 1835 and natural hybridization occurred. Selections were

made by farmers and one of the current commercial cultivars, ‘Fan Retief’, emerged and were

cultivated all over South Africa.

Due to the outbreak of Guava Wilt Disease (GWD) in the 1980’s in the Malalane area of Mpumalanga,

huge losses occurred and the guava industry in the northern parts of South Africa, based on the ‘Fan

Retief’ cultivar, declined by 80% between 1982 and 1994. This situation led to the start of the guava

breeding program at the Agricultural Research Council’s Institute for Tropical and Subtropical Crops

(ARC-ITSC) in Nelspruit, with the aim to find a solution to the disease problem. One Guava Wilt

Disease resistant rootstock, ‘TSG2’, was identified and subsequently released to the guava industry.

In February 2009 reports of ‘TSG2’ guava trees showing GWD symptoms were received from the

Levubu (Limpopo province), Nelspruit/Brondal and Nelspruit/Curlews areas (Mpumalanga province).

Studies indicated that ‘TSG2’ is affected by these outbreaks but has remained resistant to the GWD

pathogen that was originally used in the selection of ‘TSG2’. The results of the study showed that the

GWD fungus had undergone a change or a mutation.

The ARC-ITSC’s guava breeding program therefore has two objectives. Firstly, the aim is to select for

GWD resistant/tolerant plants. Secondly, new selections must not only be suited to the fresh produce

market, but must also be acceptable to the processor. Promising selections identified from the

breeding program are evaluated in the orchard (under normal disease pressure conditions), and

compared with commercial cultivars regarding yield, seediness, internal color, shape, taste and

general impression of the fruit. Physicochemical analysis was also conducted to determine the vitamin

C content, total titratable acids (TTA), total soluble solids (TSS), pH and internal fruit color.

This paper reports on the progress made towards achieving the objectives of the guava breeding

programme, as well as the challenges being experienced and the future prospects of the research


93

being done.

P35

Protein fractions explaining the variation for Mixograph peak time in South African hard red

wheat cultivars

B.S. Wentzel1, M.T. Labuschagne

2, A. van Biljon

2, M. Booyse

3 & C.W. Miles

1

1Small Grains Institute, Private Bag X29, Bethlehem 9300, South Africa



3Agricultural Research Council Biometry-Biometry, Stellenbosch, PO Box 3279, Matieland, 7602

The aim of the study was to determine the influence of flour protein content (FPC) and protein

composition on Mixograph peak time (MPT). Cultivars were evaluated over two regions. The

molecular weight distribution of unreduced wheat proteins was determined by means of size-

exclusion high performance liquid chromatography (SE-HPLC). Protein fractions were measured as

SDS-soluble and SDS-insoluble to determine proportional and quantitative variation. Combined

Pearson’s correlation was not significant for FPC and MPT. Correlations between FPC and MPT for

individual cultivars varied between not significant, negative (p ≤ 0.05) and positive (p ≤ 0.01).

Stepwise multiple linear regression analysis indicated that FPC could not explain variation for MPT.

Protein fractions contributed differently to variation in MPT. Unextractable polymeric proteins (UPP)

explained 88.89% of the variation for MPT in one of the cultivars and 17.25% for the same cultivar in

another cultivation region. Gliadins correlated negatively to MPT and explained up to 52.75% of the

variation. Proportional amounts of SDS-soluble albumins and globulins correlated positively to MPT

for certain cultivars and explained more than 40% of the variation.


94

P36

Molecular characterization of Potato Virus Y strains in South Africa

L.K. Ledwaba1 , L. Matsaunyane

2, J. Baison

3 and C. Rey

2

1University of the Witwatersrand

2Agricultural Research Council, Vegetable and Ornamental Plants (ARC-VOP), Private bag X293,

Pretoria, 0001

3Umeå Plant Science Centre, Sweden

Despite potato breeders being successful in breeding potatoes with improved yield, the cultivars are

still hosts to large number of devastating bacterial, fungal and viral pathogens. Amongst the most

devastating viral diseases, Potato Virus Y (PVY), which is a member of the Potyviridae family, is

regarded as the most economically important cultivated potato virus with up to 100 % crop loss on

those that are infected. To date, three main PVY strains have been characterised and these are

PVYO, PVY

N and PVY

C. However, due to recombination, new PVY strains were identified and these

include amongst others PVYNTN

and PVYN-W

. Due to the identified prevalence of viral recombination, it

is thought that more strains may be present, and identification as well as characterisation of these in

South Africa is important. A project was initiated aimed at utilising metagenomics through Next

Generation Sequencing (NGS) to identify and characterise these viruses. Viral symptomatic and

asymptomatic potato samples were collected from Zeekoegat potato distinct region to ensure

representation. Total RNA was isolated and metagenomic analysis was performed on RNA viral

isolates to identify and compare isolated strains to the known PVY strains. Preliminary results show

that the occurrence of the recombinant strains PVY, namely PVYNTN

and PVYN-W

, is observed to be

increasing as opposed to non-recombinant strains PVYO and PVY

N which have decreased greatly.

Furthermore, most PVY infections in the fields are observed to be caused by the recombinant strains,

which seem to be completely replacing the non-recombinant strains which are on the process of dying

out.


95

P38

Comparative differential gene expression analysis in response to PVY infection in resistant

and susceptible potato cultivars

M. Ranketse1, C. Hefer

1, L. Matsuanyane

2, and J. Baison

3

1Agricultural Research Council-Biotechnology Platform, Private Bag X5, Onderstepoort, Pretoria,

0110

2Agricultural Research Council-Vegetable and Ornamental Plants, Pretoria

3 Umeå Plant Science Institute Centre, Sweden

Potato is ranked the worlds fourth most important staple food crop, after rice, wheat and corn, due it

its nutritional value. The crop contains dietary required levels of energy, carbohydrates, protein and

fat, and a variety of essential vitamins and minerals. The gross agricultural production value of

potatoes in South Africa accounts for 43% of major vegetables produced (DAFF, 2013). Bacterial,

fungal and viral infections in potato plants are of major concern as potatoes are prone to such

infections. Amongst the most devastating viral diseases is Potato Virus Y (PVY) which is a member of

the Potyviridae family and is one of the most economically important pathogens affecting potatoes.

Gene expression profiles of potatoes during infection with PVY are unknown and this is essential in

understanding plants response to the virus, and protective mechanisms of resistant cultivars. The

current methods used to control PVY infection are costly and time consuming, therefore breeding for

cultivars resistant to PVY would be a long-term, more productive option for farmers, and it will assist

researchers in marker-assisted breeding (MAB) programs. It was suggested that transciptomics using

RNA-seq will allow for the identification of genes that are differentially regulated at different stages

during infection of potato cultivars with the PVY. Therefore this study aims to understand the disease

response of resistant cultivars, and in so doing, identify resistance genes that can be used as genetic

markers for marker-assisted breeding selection. A pre-screening analysis for RNA-Seq was

performed with two resistant lines, two susceptible and two tolerant lines. This was performed

following PVY infection glasshouse trails. Comparative differential gene expression analysis was

conducted in order to determine which genes and pathways are involved in plant host defence. The

results of this study can be implemented in MAB programs for breeding cultivars genetically resistant

to PVY.


96

P39

Mapping quantitative trait loci for blush skin in European pear

S. Ntladi1, R. Roodt-Wilding

1, J.P. Human

2, C. Bester

2 and K.R. Tobutt

2

1Department of Genetics, Stellenbosch University, Private Bag X1, Stellenbosch, 7601

2ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch 7599

The breeding programme at ARC Infruitec-Nietvoorbij for European pear (Pyrus communis L.) is

breeding cultivars with blush skin, a trait of economic value. Despite great interest in the trait, its

genetic control is still poorly understood. An existing progeny of 121 seedlings derived from the cross

of ‘Flamingo’ (a seedling of ‘Forelle’ with blush skin) by ‘Abate Fetel’ (light blush, mostly russetted) is

segregating for the trait and was scored visually over a period of three years. The seedlings were also

scored with 142 microsatellite primer pairs, mostly chosen after consulting published maps,

generating 170 microsatellite loci from which a framework map was constructed with JOINMAP4.0.

MapQTL6.0 was used to locate QTLs associated with blush skin. Two putative QTLs, located on LG5

and LG9, were found associated with blush and explained 26.0 % and 14.0% of the phenotypic

variance respectively. These results provide better understanding of genetic control of blush skin

colour derived from ‘Forelle’. Markers for the QTLs will be useful for marker-assisted selection in the

pear breeding programme for blush skin.

P40

MS-MARS facilitated pre-breeding aimed at the improvement of fungal resistance in wheat

S.W. Meintjes, L. Hess, A. Ellis and WC Botes

Department of Genetics, Stellenbosch University, Private Bag X1, Stellenbosch, 7601

The two fungal diseases that cause the most significant yield losses in wheat around the world are the

Puccinia species and Fusarium graminearum (FHB). The aim of this study is to include rust and FHB

resistance in wheat (Triticum aestivum L.). Resistance donor lines carrying rust and FHB resistance

genes were used as crossing parents together with a well established pre-breeding population of the

Stellenbosch University’s Plant breeding laboratory. The first crossing cycle was carried out

successfully with the aid of the induced dominant male sterility Ms3 gene producing a large number of

hybrid seed. The hybrid seed is currently being used for a second MS-MARS crossing cycle. The


97

validation and gene frequencies for the rust and FHB genes of interest were completed prior to cross-

pollination. This ongoing study will help to develop a pre-breeding population that will aid wheat

breeders in existing breeding programmes to enhance their genetic resistance against these fungal

pathogens.

P41

Initiation of a pre-breeding effort aimed at physiologically important traits for yield

improvement in wheat.

W. Ngcamphalala , L. Hess, A. Ellis and WC Botes


Improved yield is the ultimate trait for producers. This project aims to identify these physiological traits

associated with yield, assess them using high throughput phenotying technology and to introgress

these into an on-going male sterility mediated marker assisted recurrent selection scheme (MS-

MARS) nursery via backcross breeding. To achieve this as a first objective a field trial consisting of a

diverse set of high known high yielding genotypes were accessed under field conditions the past

season. Using a Remotely Piloted Aircraft System (drone) mounted with both an RGB and a NGB

camera, images of the trial were taken and analysed to assess plant traits and initiate the

establishment of appropriate models for data analyses.

P42

Initiation of a pre-breeding effort aimed at water stress resistance traits for yield improvement

in wheat.

J. Mthembu , L. Hess, A. Ellis and WC Botes


The aim of this study was the initiation of a pre-breeding effort aimed at water stress resistance traits

for yield improvement in wheat. A set of diverse genotypes are being screened for water stress

resistance utilizing A reticulated hydroponic system (RHS). The screening has been divided into two

stages. The first stage has been completed already. Growth rate, dry weight, fresh weight, number of


98

leaves, root length and relative water content (RWC) has been measured to evaluate water stress.

Combined analysis of variance indicated statistical significanct difference among the genotypes under

investigation.

P43

Initiation of a pre-breeding effort aimed at salinity resistance traits for yield improvement in

wheat.

N. Cebekhulu, L. Hess, A. Ellis and WC Botes


Soil salinity is becoming an ever increasing problem in especially the irrigation wheat production

areas of the world. In order to address this problem a pre-breeding project aimed at salinity resistance

traits in wheat is currently being initiated. As a first objective a diverse set of genotypes are currently

being screened. In order to identify the best performers among the genotypes, multiple agronomical

parameters associated with tolerance were identified using a hydroponic reticulation system in which

salinity can be induced under controlled conditions.

99

List of delegates

Surname Initials Institution E-mail

Adebola P.O. Agricultural Research Council

[email protected]

Alberts M.J.A. Monsanto [email protected]

Asiwe J. University of Limpopo [email protected]

Bairu M. UKZN [email protected]

Bijzet Z. ARC-ITSC [email protected]

Blubaugh A.B. Kincaid Equipment [email protected]

Booyse M. ARC Biometry [email protected]

Boshof W.H.P. Pannar [email protected]

Botes W.C. Stellenbosch University [email protected]

Boyd L.A. National Institute of Agricultural Botany

[email protected]

Brauteseth E.M. Pannar Seed (Pty) Ltd [email protected]

Bresler A.P. PANNAR [email protected]

Breytenbach S.O. SENSAKO PTY LTD [email protected]

Brink W.A. Sappi [email protected]

Cele M.J. INSTITUTE FOR COMMERCIAL FORESTRY RESEARCH

[email protected]

Chiuta N.E.C University of Fort Hare [email protected]

Coetzee K. ARC-Small Grain Institute [email protected]

Combrink N.K. ARC - ITSC [email protected]

Dattendorfer D.P. Wintersteiger AG [email protected]

De Groot G. SENSAKO PTY LTD [email protected]

De Groot S. SENSAKO PTY LTD [email protected]

De Jager J.H. Monsanto [email protected]

De Klerk D. SABBI [email protected]

Du Toit A.G.A. PANNAR SEED [email protected]

Dube P.B. Pannar Seed (Pty) Ltd [email protected]

Dunlop E.D. PANNAR SEED [email protected]

Dweba C.C. ARC-Small Grain Institute [email protected]

Egger E.A. Wintersteiger AG [email protected]

Elago S.N. Stellenbosch University [email protected]

Ellis A. Stellenbosch University [email protected]

Erasmus T.E Incotec [email protected]

Figlan S. ARC-Small Grain Institute [email protected]

Fly R.D. Monsanto [email protected]

Fourie D. Pioneer [email protected]

Frey S. LemnaTec GmbH [email protected]

Galloway G.M.G. Sappi [email protected]

Gerrano A.S. ARC-Vegetable and Ornamental Plant Institute

[email protected]

Groenink S.R. Incotec [email protected]

Gwata E.T. University of Venda [email protected]

Haesaert G. University of Ghent [email protected]

Hajari E. Agricultural Research Council

[email protected]

Ham H. Stellenbosch University [email protected]

mailto:[email protected]



11th SAPBA Symposium List of delegates

100


Hannweg K. ARC-Institute for Tropical and Subtropical Crops

[email protected]

Heita H.T.N. Stellenbosch University [email protected]

Herselman L. University of the Free State

[email protected]

Horn M. SENSAKO PTY LTD [email protected]

Hörstmann C.U. ARC Infruitec-Nietvoorbij [email protected]

Human C. Sakata Seed [email protected]

Human C.F. Institute for Tropical and Subtropical Crops

[email protected]

Human T. ARC Infruitec-Nietvoorbij [email protected]

Husselman J.H. ARC-ITSC [email protected]

Jansen M.J. LemnaTec GmbH [email protected]

Jansen van Rensburg

W.S. ARC [email protected]

Jarvie J.A. Pannar Seed (Pty) Ltd [email protected]

Joshi S.V. South African Sugarcane Research Institute

[email protected]

Joubert E. Monsanto [email protected]

Kanzler A. Sappi [email protected]

Kloppers F.J. PANNAR SEED [email protected]

Knight V.M. PANNAR SEED [email protected]

Koekemoer F.P. SENSAKO PTY LTD [email protected]

Koekemoer M.L. DuPont Pioneer [email protected]

Kriel J.H. ARC Infruitec-Nietvoorbij [email protected]

Kwalimba L. ARC [email protected]

Labuschagne J.J. AE Solutions (Pty) Ltdf [email protected]

Labuschagne M.T. University of the Free State

[email protected]

Landman N.J. Klein Karoo Seed Marketing

[email protected]

Lapawsky C.A. EFS & SRES [email protected]

Lashbrooke J.G. ARC [email protected]

Laurie S.M. ARC-Vegetable and Ornamental Plant Institute

[email protected]

Le Roux C. CenGen (Pty) Ltd [email protected]

Ledwaba L.K. University of the Witwatersrand

[email protected]

Leeuwner D.V. Klein Karoo Seed Marketing

[email protected]

Lesch A.J.G SENSAKO PTY LTD [email protected]

Letsoalo I.M. University of Limpopo [email protected]

Lichakane M.L. South African Sugarcane Research Institute

[email protected]

Lochner T.C. Pannar [email protected]

Mabaso F.S. Stellenbosch University [email protected]

Makhumbila P. ARC [email protected]

Makome S.L. Pioneer Hi-Bred [email protected]

Malan A. ARC-SGI [email protected]

Maphumulo S.G University of KwaZulu-Natal

[email protected]

Maré A. University of the Free State

[email protected]


101


Mathew I. University of KwaZulu-Natal

[email protected]

Matsaunyane L.B.T. ARC [email protected]

Mavengahama S. ARC-Vegetable and Ornamental Plant Institute

[email protected]

Mba C. AGPMG-FAO [email protected]

Mbulawa Z.T.L. ARC Infruitec-Nietvoorbij [email protected]

Mbuma N.W. South African Sugarcane Research Institute

[email protected]

Meintjies S.W. Stellenbosch University [email protected]

Mhelembe K.G. ARC Infruitec-Nietvoorbij [email protected]

Middleton F.L. Pannar Seed (Pty) Ltd [email protected]

Mofokeng A. ARC-Grain Crops Institute [email protected]

Mphahlele M.M. University of Pretoria [email protected]

Mtembu J. Stellenbosch University [email protected]

Mtshali L.N.M. South African Sugarcane Research Institute

[email protected]

Müller O. DuPont Pioneer [email protected]

Mutawila C. Monsanto [email protected]

Mutengwa C.S. University of Fort Hare [email protected]

Naidoo S. Sappi Forests [email protected]

Naidoo S.I.M. ARC-Vegetable and Ornamental Plant Institute

[email protected]

Namo M.P. Monsanto [email protected]

Ncube E. ARC-Small Grain Institute [email protected]

Nel A. Sappi [email protected]

Netshifhefhe N.E.I. Stellenbosch University [email protected]

Nevhudzholi K.M. University of Venda [email protected]

Ng P. Michigan State University [email protected]

Ngcamphala W. Stellenbosch University [email protected]

Nondumiso C. Stellenbosch University [email protected]

Ntladi S. Stellenbosch University [email protected]

Ntshakaza P. ARC [email protected]

Onsando O.J. University of the Free State

[email protected]

Paterson J. Aerobotics [email protected]

Pelser F.S. University of the Free State

[email protected]

Pfunde C.N. University of Fort Hare [email protected]

Pieterse W-M. ARC Infruitec-Nietvoorbij [email protected]

Potgieter J.J.W. PRIVATE CONSULTANT [email protected]

Pretorius Z.A. University of the Free State

[email protected]

Prins R. CenGen Pty Ltd & University of Free State

[email protected]

Prinsloo L. EFS&SRES [email protected]

Ranketse M. ARC-Biotechnology Platform

[email protected]

Rhoda R. Stellenbosch University [email protected]

Rose L.J. Stellenbosch University [email protected]

Safodien S. ARC [email protected]



102


Schmidt J.S. Zuern Harvesting GmbH & Co. KG

[email protected]

Schroder A.W. Monsanto [email protected]

Sengwayo S.H. South African Sugarcane Reserch Institute (SASRI)

[email protected]

Shandu S.F. ARC-Grain Crops Institute [email protected]

Shargie N.G. ARC [email protected]

Shimelis H.A. University of KwaZulu-Natal

[email protected]

Sikhakhane T.N. ARC [email protected]

Sippel A.D. ARC-ITSC [email protected]

Sithole M.P.S. PANNAR SEED [email protected]

Smit C. CenGen (Pty) Ltd [email protected]

Smit F.J. SABBI [email protected]

Soeker M.K. ARC [email protected]

Springfield L. Stellenbosch University [email protected]

Sydenham S.L. ARC-Small Grain Institute [email protected]

Thompson G.D. ARC-Biotechnology Platform

[email protected]

Thovhogi F. University of Venda [email protected]

Tobutt K.R. ARC Infruitec-Nietvoorbij [email protected]

Tolmay V.L. ARC-Small Grain Institute [email protected]

Tongoona P.B. University of Ghana [email protected]

Truluck C. Spoor & Fisher [email protected]

Tsilo T.J. ARC-Germplasm Development

[email protected]

Unruh S.L.U. SRES (Seed Research Equipment Solutions)

[email protected]

Van Biljon A. University of the Free State [email protected]

Van der Merwe F.B. Pioneer Hi-Bred [email protected]

Van der Merwe R. University of the Free State [email protected]

Van Eeden E. SENSAKO PTY LTD [email protected]

Van Huyssteen J. SANSOR [email protected]

Van Schalkwyk H.J. University of the Free State [email protected]

Van Wyk J.J.R. CenGen Pty Ltd & University of Free State

[email protected]

Van Zyl C.J. PANNAR SEED [email protected]

Van Zyl J.V. Wintersteiger AG [email protected]

Visagie J.A. Pannar [email protected]

Visser B. University of the Free State [email protected]

Wessels E. CenGen (Pty) Ltd [email protected]

Wessels R. SENSAKO PTY LTD [email protected]

Willemse S. ARC-Institute for Tropical and Subtropical Crops

[email protected]

Wilson G.A.W. HarvestMaster [email protected]

Zhou M. South African Sugarcane Research Institute

[email protected]


8th SAPBA Symposium Index

103

Index of Authors

Asiwe, J.A.N., 30 Bairu, M.W., 44 Bijzet, Z., 32 Booyse, M., 42 Brink, W., 62 Cebekhulu, N., 98 Cele, J., 38 Combrink, N., 33 Dweba, C., 62 Figlan, S., 64 Froneman, I.J., 35 Galloway, G., 65 Gerrano, A.S., 66 Gwata, E.T., 63 Haesaert, G., 20 Hajari, E., 67 Ham, H., 68 Hamer, M., 69 Hannweg, K., 70 Hörstmann, C.U., 25 Human, C., 36 Human, T., 28 Husselman, J., 70 Jansen van Rensburg, W., 71 Jansen van Rensburg, W., 44 Jansen, M., 18 Joshi, S., 60 Kanzler, A., 54 Kwalimba, L., 72 Labuschagne, M., 45 Lashbrooke, J., 52 Laurie, S., 31 Ledwaba, L.K., 94 Letsoalo, I.M., 61 Lichakane, M., 34 Makhumbila, P., 73 Makome, L., 53 Malan, A.F., 74 Maphumulo, S., 75 Maré, A., 58 Mathew, I., 43 Mba, C., 19 Mbulawa, Z., 76

Mbuma, N., 40 Meintjes, S.W., 96 Mhelembe, K.G., 51 Mofokeng, A., 77 Mphahlele, M.M., 39 Mthembu, J., 97 Mtshali, L., 37 Naidoo, S., 79 Naidoo, S., 49 Nel, A., 24 Netshifhefhe, N., 78 Nevhudzholi, K.M., 80 Ng, P.K.W., 22 Ngcamphalala, W., 97 Ntladi, S., 96 Ntshakaza, P., 81 Onsando, J., 47 Paterson, J., 19 Pelser, F.S., 48 Pieterse, W., 50 Pretorius, Z.A., 22 Prins, R., 82 Ranketse, M., 95 Rose, L., 59 Safodien, S., 83 Sengwayo, S., 41 Shanda, S.F., 84 Shimelis, H., 27 Sikhakhane, T.N., 85 Sippel, A.D., 35 Smit, C., 86 Smit, C., 57 Soeker, M.K., 29 Sydenham, S.L., 87 Thovhogi, F., 88 Tolmay, V., 89 Van Biljon, A., 46 Van der Merwe, R., 90, 91 Van Schalkwyk, H.J., 56 Visser, B., 55 Wentzel, B.S., 93 Willemse, S., 92 Zhou, M., 26

11th protea hotel technopark, stellenbosch 8 - 10 march 2016 book 11t… · session 1: general...

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