J. Appl. Hort., 3(2):95-97, July-December, 2001

Variation in canopy characteristics of mango(Mangifera indica L.) cultivars from diverseeco-geographical regions

Shailendra Rajan, Ram Kumar and S.S. Negi

Central Institute for Subtropical Horticulture, Rehmankhera, P.O. Kakori, Lucknow-227107, India.

AbstractA study was conducted on 26 important Indian mango cultivars to examine their foliage density and canopy diffuse non-interceptance.Indirect measurement of Leaf area index (LAI) and diffuse non-interceptance (DNI) made using output of concentric silicon detectors,placed at five zenith angles on sensing head of LAI-2000 recorded significant variability in foliage density (LAI=1.18-4.48). Diffusenon-interceptance values also exhibited large variation and ranged from 0.02 to 0.36. UPGMA cluster analysis of the data revealedthat Bangalora, Fazri, Neelum, Vanraj, Dashehari, Alphonso, Lucknow Safeda and Banganapalli had similarity in tree leaf component.Nisar Pasand, Kishan Bhog and Bombay Green had compact and dense canopy with more foliage component. Papatio and Fernandinexhibited comparatively less foliage under Lucknow conditions. Prabhashankar and Chausa showed similarity and were closer tocompact canopy group. In general, east and north Indian cultivars recorded more foliage component, whereas Fernandin and Papatiocanopies exhibited high DNI values. The cultivars recording more DNI produced fruits with better colour.

Key words: Mango, Mangifera indica L., foliage density, leaf area index, canopy, Indian cultivars

Not much information is available on the variation in foliagedensity in mango varieties. Therefore, the present study considersthe differences in canopy characteristics of important Indian mangocultivars under subtropical conditions studied by indirect methodi.e., gap fraction inversion model.

Methods and materialsThe study was conducted on 26 Indian mango cultivars at CentralInstitute for Subtropical Horticulture, Rehmankhera, Lucknow.Twenty years old trees, planted at the distance of 10 x 10m, wereselected for the study. Radiation measurements, above and belowcanopy were taken on cloudy day with the help of five concentricsilicon ring detectors on the sensing head of LAI-2000 (LI- Cor,Inc. Lincoin, NE). The data generated by concentric detectors,placed at five zenith angles was used for calculating gap fraction.Readings of above and below-canopy light conditions were usedfor the calculation of LAI and DNI. Below-canopy data were takenat four compass directions. Above-canopy data were taken bywalking to an adjacent open space, immediately after recordingeach below-canopy reading. The LAI was calculated from thefield measurements by using the software support for the plantcanopy analyzer C-2000-90 Version 2.14 (LI-COR,1992).Cultivars were grouped by subjecting the data to UPGMA(unweighted pair-group method using arithmetic averages) clusteranalysis.

Results and discussionMango cultivars exhibited significant differences for their canopycharacteristics (Fig.1a,b). The cultivars had mean LAI value 2.94with a range of 1.18-4.48 whereas, mean diffuse non-interceptance (fraction of the sky which can be seen from the

IntroductionLight interception is directly related with total dry matter productionin several crops (Duncan et al., 1973 and Monteith, 1977) and alsoholds good for fruit trees (Jackson and Palmer, 1977), however, thepartitioning of dry matter is dependent on within canopy lightdistribution also. Optimised light distribution within canopy and itsinteraction with different parts is important for maximizingphotosynthesis, flower bud formation, fruit growth and colourdevelopment (Rajan and Lal, 1999). Better understanding ofcanopy micro-climate particularly with regards to light distributionis associated with cultivars, cultural practices and climatic conditions.In tropics, several subtropically adapted mango genotypes likeLangra and Dashehari develop huge and dense canopy with highleaf component indirectly causing poor light penetration, floweringand fruit quality (Yadav and Rajan, 1993).

Direct measurement of LAI in large heterogeneous tree canopiesis difficult (Martens et al., 1991). For replacing destructive leafharvest method, which is usually undesirable and impractical fortree crops, researches have led to the development of methodsbased on allometry (Whittaker and Woodwell, 1968; Marshalland Waring, 1986). Refinements in allometric methods areresponsible for improvement in indirect methods (Grier andWaring, 1974; Whitehead et al., 1984), which still require muchlaborious fieldwork before its application in the orchard. Gapfraction analysis is one of the indirect method of estimating LAI(Campbell and Norman, 1989; Norman and Campbell, 1989). Ithas been successfully applied to the small plants and also to foresttree canopies. Recently, advances in instrumentation for measuringgap fraction in plant canopies and the development of gap fractioninversion models, from which canopy characteristics such as LAIand mean leaf inclination angle can be inferred, have increasedthe attractiveness of this method (Campbell, 1986).

canopy) was 0.11 and it ranged from 0.02 to 0.36. The patternof frequency distribution of LAI and DNI in cultivars wasdifferent (Fig. 2a,b) indicating curvilinear relationship betweenthese two parameters. Most of the cultivars had LAI between 2-4. Whereas, more number of cultivars (88.4%) recorded DNI <0.2. In general, east and north Indian cultivars like BombayGreen, Chausa, Nisar Pasand, Himsagar and Prabhashankerrecorded more foliage component (LAI>4). Fernandin, Papatioand Rataul canopies exhibited high diffuse non- interceptancevalues (DNI > 0.3). Most of the genotypes showing less diffusenon- interceptance like Bombay Green, Nisar Pasand andPrabhashanker produced fruits with dark green colour at harvest.Since mango genotypes show eco-geographical dependence withregard to adaption, growth and productivity, foliage distributionwithin canopy is significantly affected by genotype xenvironment interaction.

The results indicated that the genetical divergence in the canopycharacteristics like foliage density and diffuse non-interceptanceexist in mango. These parameters were used for grouping ofcultivars based on similarity percentage. Clustering patternindicated that cultivars, Bangalora, Fazari, Neelum, Vanraj,

Dashehari, Alphonso and Lucknow Safeda have similarity incanopy leaf component. Kesar, Mallika, Mankurad and Mulgoawere grouped in one cluster having semi compact canopy. NisarPasand, Kishan Bhog and Bombay Green had dense canopy withmore foliage component. Papatio and Fernandin exhibitedcomparatively less foliage under Lucknow conditions.Prabhashanker and Chausa showed similarity with each otherand were closer to compact canopy group of Nisar Pasand,Kishan Bhog, Bombay Green. Himsagar and Langra showedsimilarity in canopy development behaviour (Fig. 3).

Variation in foliage density and DNI also indicates that there issignificant difference in canopy structure of different cultivarsand suggests that other than genotypic influence, this may occurunder the influence of factors i.e., vegetative growth, regularity ofcropping and growth cycles in a year. Cultivars differ significantlyin canopy architecture, thus exhibiting variation in DNI. Differencein foliage component of scion has been recorded with differential vigourof the scion imparted by rootstocks (Verheij and Verwer, 1973).

Percent Similarity

AlphonsoNeelamVanrajBangloraFajriDashehariLucknow SafedaHimsagarLangraBombayBombay GreenKishan BhogNisar PasandChausaPrabhashankerBanganpalliKesarMallikaMankuradMulgoaKhas Ul KhasMalihabad SafedaZardaluRataulFernandinPapatio

52 60 68 76 84 92 100

Fig. 2a. Frequency distribution ofleaf area index and Fig. 2b.Frequency distribution of diffusenon-interceptance in 26important mango cultivars.

Fig. 1. Variation in LAI (a) and diffuse non interceptance (b) in differentcultivars of mango studied under subtroical conditions.

0 1 2 3 4 5 6LAI

LSD ( =0.05)p

DNI

LSD ( =0.05)p

Fig. 3. UPGMA clustgering of genotypes based on LAI and DNI values

(a) (b)

96 Rajan et al.- Canopy characteristics of mango (Mangifera indica L.) cultivars

FREQ

UE

NC

Y

LEAF AREA INDEX

0123456789

10111213

0 1 2 3 4 5DIFFUSE NON INTERCEPTANCE

0

2

4

6

8

10

12

14

16

18

0.0 0.1 0.2 0.3 0.4 0.5

Fig. 2bFig. 2a

Foliage distribution in several mango cultivars is not uniformspecially under North Indian conditions. Cultivars from south andwest India show low foliage component as compared to north andeast Indian cultivars. Some cultivars may also exhibit differentgrowth habit under north and south Indian conditions due to ceasinggrowth under extreme temperatures in subtropics. In the presentinvestigation, Fernandin and Papatio performed entirely differentthan the other cultivar (Fig. 3). The similarity between the cultivarsfrom different ecological regions was also observed which indicatesthat differential canopy development is not solely dependant onthe adaption rather variability in canopy characters exists in cultivarsof the same eco-geographical region.

The relationship between yield and light interception by the canopy,which is dependant on the size and foliage density of canopy is notworked out in mango. However, light distribution within canopyis universally related with the foliage density. The paucity ofinformation on the foliage component of mango cultivars is mostlybecause of non-availability of indirect canopy structuremeasurement technique and direct measurement technique beingtedious and practically impossible for large mango tree canopy.The studies on relationship between leaf area index and lightinterception have been conducted in fruit trees by Heinicke (1973),Jackson (1970) and Verheij and Verwer (1973). Models andexperimental data on light interception in orchards havedemonstrated that dry matter and yield are proportional to totallight interception, whereas fruit quality and flowering depends onlight distribution within the canopy (Jackson, 1980, Robinson andLakso, 1989, Jackson and Palmer,1977). These studies haveindicated the importance of indirect techniques, which are basedon the closed coupling between light penetration and canopystructure. These alternative methods use canopy gap fraction atvarious angles (Norman and Campbell, 1989). Gap fractions havebeen measured by Fish Eye photograph (Anderson, 1971) andLinear light sensor (Walker et al., 1988). However, other techniqueslike hemispheric photographs did not yield an accurate orchardLAI. Inaccuracies in gap sizes may result from subjectivethresholding of photographs (Becker et al., 1989).

Significant variability among Indian cultivars was observed indiffused non interceptance (DNI). Theoretically the quantity of thisparameter may range between 0-1, which indicates the probabilityof diffused radiation from the upper hemisphere penetrating thecanopy to the particular location. This parameter can be used as anindex for studying light distribution within the mango canopy. Thecultivars like Fernandin, Papatio, Malihabad Safeda and Rataulrecorded high DNI values. Thus, the fruits and shoots developing inthese canopies are more exposed to solar radiation and thus producingbetter coloured fruits and flowering shoots.

The study suggested that the cultivar with high foliage density andlow DNI values can be modified by imposing pruning treatment.Pruning after harvest by removing growing shoots may be usefulin improving DNI values.

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