kutsaga releases a katambora rhodes grass variety (g hr1) for … · character landrace g hr1 leaf...
TRANSCRIPT
Kutsaga releases a Katambora
Rhodes grass variety (G HR1) for
nematode management under
tighter rotations
Justify Shava and Privilage Makunde
CORESTA CONGRESS 2016
TOBACCO RESEARCH BOARD
KUTSAGA
Munyaradzi Shamudzarira
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PRESENTATION OUTLINE
• Introduction
• Variety Development
• Variety evaluation (Field trial)
• Results
• Conclusions
• Acknowledgements
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• Rhodes grass (Chloris gayana) introduced from the Cape Province in the early 1900s
• Important crop in soil structure management and root knot management
• Suppresses root-knot nematodes in tobacco farming systems
INTRODUCTION
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BACKGROUND
KM10 – AFTER GRASS KM10 – AFTER KM10
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BACKGROUND
• The grass used for 3 to 4 years before the next tobacco crop
• However, after the land redistribution, 3 to 4 year rotations not possible due to reduced land sizes
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BACKGROUND
• Additionally, grass out crossing in nature- gradual loss of RKN resistance over time
• Therefore necessary to address these limitations to RKN management
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OBJECT IVES
• To develop a grass with higher RKN
suppression ability for use in shorter rotations
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METHODOLOGY
1. Development of the variety
2. Greenhouse evaluation of the
variety
3. Field evaluation
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• Recurrent selection
• Intercrossing of the resistant selections
• Repeatedly inoculated with root-knot nematodes and assessed for RK in the greenhouse
Variety Development
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• Resistant segregants identified
• Resistant selections passed on to next cycle (6 cycles)
• New variety Grass High Root Knot Resistance 1 (G HR1) developed
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DESCRIPTION OF GRASS
CHARACTER LANDRACE G HR1
Leaf Colour Green ,purple tinged sheath Pale green speckled sheath
Growth Habit Prostate Stoloniferous
Overall
Appearance
Stemy, purple tinged
internodes
Stemy, white tinged to light
green internodes
Days to flower 90 90
Nematode
resistance
Good Excellent
Flower Colour Light purple Non-pigmented pale yellow
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DESCRIPTION OF GRASS
CHARACTER LANDRACE G HR1
Leaf Colour Green ,purple tinged sheath Pale green speckled sheath
Growth Habit Prostate Stoloniferous
Overall
Appearance
Stemy, purple tinged
internodes
Stemy, white tinged to light
green internodes
Days to flower 90 90
Nematode
resistance
Good Excellent
Flower Colour Light purple Non-pigmented pale yellow
GHR 1 Landrace
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DESCRIPTION OF GRASS
CHARACTER LANDRACE G HR1
Leaf Colour Green ,purple tinged sheath Pale green speckled sheath
Growth Habit Prostate Stoloniferous
Overall
Appearance
Stemy, purple tinged
internodes
Stemy, white tinged to light
green internodes
Days to flower 90 90
Nematode
resistance
Good Excellent
Flower Colour Light purple Non-pigmented pale yellow
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APPEARANCE OF G HR1
G HR1 Landrace
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APPEARANCE OF G HR1
G HR1 Landrace
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GREENHOUSE EVALUATION
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• G HR1 evaluated against the Landrace
• Done in 20 L microplots
• Inoculated with 5 000 RKN juveniles per
pot
Materials and Methods
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• Mean No of eggs/root system
• Destructive sampling and root
galling assessments done
Measurements
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Tobacco root galling scale
0
6
3 1
4 5 7
2
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Tobacco root galling scale
0
6
3 1
4 5 7
2
8
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RESULTS
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MEAN NO OF EGGS / PLANT
110 000
115 000
120 000
125 000
130 000
135 000
140 000
145 000
Landrace G HR1
Egg
cou
nts
a
b
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Nematode Host status of G HR1 vs Landrace
CV Egg count Mean gall
rating
%
resistance Landrace 143 417 1.1 65
G HR 1 122 989 0.53 93
F-PROBABILITY 0.02 0.04 0.01
SED 12 453 0.13 1.2
LSD 15345.1 0.32 20.3
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RELATIVE % CHANGES IN NEMATODE POPULATIONS
UNDER LANDRACE AND GHR1
Year/ Season
Length of grass
rotation
Landrace % change in
nematode
population
G HR1 % change in
nematode
population
1 185 000 - 185 000
2 143 417 -22.5 82 980 -55.1
3 82 980 -42.1 22 728 -72.6
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VARIETY EVALUATION (FIELD
TRIAL)
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Materials and Methods
• The study was conducted at Kutsaga Research Station
• Agro Ecological Region IIA of Zimbabwe, coordinates of 17˚ 54′ South and 31˚ 08′
• Elevation - 1496 m above sea level.
• Max and Min Temp. of 32˚C and 18˚C respectively.
• Average annual rainfall is 800 to 1000mm
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Design: RCBD. 2 x 3 Factorial with 6 replications(3 buckets/plot)
Factor 1 (Rotation)
1. Landrace
2. G HR1
Materials and Methods
Factor 2 (Rotation time)
1 Year
2 Years
3 Years
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Materials and Methods
• KM 10 (Susceptible) and K RK26R (Tolerant)
• Planted nematode susceptible KM10 for one season
• Bioassays done to determine nematode population.
• Tobacco crops planted sequentially for 3 yrs
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Measurements
• Tobacco root galling (year 1 to 3)
• Tobacco yield (year 1 to 3)
• Nematode population build up assessments
• Grass herbage and seed yield
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Measurements
• Tobacco root galling (year 1 to 3)
• Tobacco yield (year 1 to 3)
• Nematode population build up assessments
• Grass herbage and seed yield
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Data Analysis
• ANOVA – Gentsart 18th edition
• LSD mean seperation
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Results
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ROOT GALLING - AFTER 1 YEAR
0
2
4
6
8
KM10 K RK26R
Gal
l rat
ing
L.S.D = 0.2
Landrace G HR1
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TOBACCO YIELD (KG/HA) – 1 YEAR
0
500
1000
1500
2000
2500
KM10 K RK26R
Yie
ld
L.S.D = 119.1 Landrace G HR1
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Comparative gall ratings (year 2 and 3)
0
1
2
3
4
5
6
Year 2 Year 3 Year 2 Year 3
KM10 K RK26
Gal
l Rat
ing
L.S.D = 0.2
Landrace G HR1
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COMPARATIVE YIELD PERFORMANCE OF TOB. CV
2000
2200
2400
2600
2800
3000
3200
3400
Year 2 Year 3 Year 2 Year 3
KM10 K RK26
Yie
ld
L.S.D = 128.2 Landrace G HR1
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HERBAGE YIELD (TONNES/HA)
6.65
6.7
6.75
6.8
Landrace G HR1
6.7
6.8 H
erb
ag
e Y
ield
to
nn
es/
ha
LSD = 1.01
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SEED YIELD (KG/HA)
LSD = 302
0
200
400
600
800
1000
1200
Landrace G HR1
See
d Y
ield
(kg
/ha)
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Conclusion
• G HR1 suppressed root-knot nematodes better than the Landrace grass after a susceptible tobacco crop
• GHR1 in conjunction with a resistant cultivar provide better nematode control and yields
• GHR1 give better yields in a comparatively shorter rotation than Landrace
• G HR1 can be used under shortened rotations
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Recommendations
• It is therefore recommended that G
HR1 be used in shorter rotations of two
years since it has improved nematode
suppression capacity.
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Thank You
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