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SWATANTRA MISHRA, M. SHANTHI PRIYA*, M. REDDISEKHAR AND G. MOHAN NAIDU
Department of Statistics and Mathematics, S.V. Agricultural College, ANGRAU, Tirupati.
Evaluation of 48 genotypes of cluster bean was taken up in dry land farm of S.V. Agricultural College, Tirupati in a
randomized block design with three replications during kharif, 2014. Based on Mahalanobis D2
analysis, 48 genotypes were
grouped into 12 clusters. Genotypes that originated from different eco-geographical regions grouped together in the same cluster
which suggested that there was no correlation between geographic diversity and genetic diversity. The maximum inter-cluster
distance was recorded between cluster IX and cluster XI, while the minimum inter-cluster distance was found between II and III
cluster.
Cluster bean, genetic divergence, Mahalanobis D2
Cluster bean (2n = 14) is an under exploited leguminous vegetable belonging to the family Fabaceae. It is commonly known as guar, chavlikayi and khutti. Guar is grown in kharif season in arid and semi arid regions of India. It is a drought hardy and deep rooted annual legume. Guar is one of the most important and potential vegetable cum industrial crop grown for its tender pods for vegetable purpose and for endospermic gum [30-35%]. In recent years guar has achieved the status of an industrial crop due to the water soluble natural polymer galactomannon gum. Now guar has become an alternative remunerative crop with high adaptability suited for growing in arid regions of the world. Gum having good binding properties is derived from the endosperm of the seed. Guar gum is an important ingredient in producing food emulsifier, food additive, food thickener and other guar gum products. Its
usage as a thickening agent and emulsifier in the oil and gas extraction industry for hydraulic fracturing of subsurface shale has made it a much sought after product in international market.
Despite its importance, little attention has been given for cluster bean genetic improvement in the past. Hence, there is a need to enhance the productivity levels of cluster bean. Progress in breeding for economic characters depends largely on the magnitude and nature of variability present in germplasm. Assessment of genetic diversity is an essential pre-requisite for identification of potential parents for hybridization in any crop improvement programme. Diverse parents are expected to yield higher frequency of heterotic hybrids in addition to generating abroad spectrum of variability in segregating generations. The D2 statistics is a useful multivariate statistical tool for effective discrimination among various genotypes on the basis of genetic diversity (Murthy and Arunachalam,1966).
The experimental material comprised of 48 diverse genotypes of cluster bean obtained from Rajasthan Agricultural Research Institute Durgapura, Rajasthan. The experiment was laid out in Randomized Block Design replicated thrice. The crop was sown on 15th July, 2014. Each genotype was sown in single row of 6m length with a spacing of 0.45 m between rows and 0.2 m between plants within a row. Fertilizers were applied at recommended dose of 20 Kg N and 40 Kg P2O5 per hectare in the form of urea and single super phosphate. Weeding and plant protection operations were taken up as and when needed during the crop growth period and life saving irrigation was given to raise good crop. Observations were recorded on randomly chosen five competitive plants in each genotype in each replication for plant height, number of branches per plant, number of clusters per plant, number of pods per cluster, number of pods per plant, pod weight, pod length, number of seeds per pod, 100 Seed weight, shelling percentage, endosperm percentage, gum percentage, pod yield per plant and seed yield per plant. Mean value of five competitive plants was expressed as mean of the respective character. Data for days to 50 per cent flowering and days to maturity was recorded on plot basis. The data collected on different characters was analyzed by Mahalanobis generalized distance (D2) analysis.
The quantitative assessment of genetic divergence was made by adopting Mahalanobis’s D2 statistics for yield and its contributing traits. Wilks test showed highly significant differences among the genotypes for the aggregate effect of 16 characters which suggested the existence of considerable divergence in the material hence, D2 analysis was carried out following procedure given by Rao (1952).
All the 48 genotypes of cluster bean were grouped into twelve clusters using Tocher’s method (Singh and Chaudhary, 1985). The distributions of genotypes into 12 clusters are presented in Table 1.
Cluster I included the largest number of genotypes (21) followed by cluster VII with four genotypes and cluster VIII, X and XII with three genotypes and remaining seven clusters II, III, IV, V, VI, IX and XI had included two genotypes each.
The cluster I was the largest comprising of 21 genotypes originated from different regions and this might be due to free flow (or) exchange of breeding material from one place to another and/or the unidirectional selection practiced by breeders of different locations. Moreover, the genotypes originated from different ecogeographical regions were grouped together in the same cluster which suggested that there was no correlation between geographic diversity and genetic diversity.
Similar findings of Rai et al. (2012), Kumar et al. (2013), Manivannan and Anandakumar (2013) and Sivia
and Dahiya (2014) corroborated that the distribution of genotypes from different eco-geographical regions into clusters was at random indicating geographical distribution does not necessarily exhibit genetic divergence.
The intra and inter-cluster D2 and D values among 12 clusters are given in Table 2. Intra cluster average D2
values ranged from 12.46 to 82.50. Among the clusters, cluster XII had the maximum intra-cluster distance (82.50), while the minimum was recorded in cluster II (12.46).
The maximum inter-cluster distance was recorded between cluster IX and cluster XI (205.48), while the minimum inter-cluster distance was found between cluster II and cluster III (34.20). Inter-cluster distances were higher than intra-cluster distances which indicated the existence of substantial diversity among the genotypes. Selection of parents for crossing from divergent clusters may result in heterotic expression for yield and quality traits.
Raghuprakash et al. (2008) Pathak et al. (2009) and Muthuselvi and Shanthi (2013) also reported greater diversity between clusters based on inter cluster distance.
The mean performance of clusters for 16 characterswas presented character wise in Table 3. Cluster mean
for days to 50% flowering ranged from 26.00 days to 28.83 days with a general mean of 27.30 days. Among all the clusters, Cluster VI took 26 days for 50% flowering while cluster IV took 28.83 days. Out of 12 clusters, 7 clusters were early in flowering and 5 clusters were late in flowering when compared to general mean.
Days for maturity among this clusters varied from 89.89 to 99.67 days with mean maturity of 94.48 days. Early maturity was exhibited by cluster XII (89.89 days) whereas cluster IV (99.67 days) showed late maturity. Out of 12 clusters, 6 clusters registered early maturity and 6 clusters were late in maturity when compared to
general mean.
Plant height ranged from 118.83 to 190.50 cm with a general mean height of 142.41 cm. Among the clusters, cluster XI was found to be the tallest (190.50 cm) whereas cluster Vas the shortest (118.83 cm). Six clusters were taller in height and 6 clusters were shorter in height when compared to the general mean of 142.41 cm. The highest number of branches per plant was recorded by the cluster IV and cluster IX (9.67) whereas cluster XI recorded less number of branches (1.83). Eight clusters had more number of branches per plant than the general mean (7.35). Maximum number of clusters per plant was recorded in the cluster IX (77.83) whereas minimum was observed in the cluster XI (24.00). Three clusters have exceeded the general mean value of 37.81.More number of pods per cluster was observed in the cluster XI (6.09) whereas cluster IX (3.26) recorded the lowest. Three clusters have exceeded the general mean value of 3.93
Number of pods per plant ranged from 113.58 to 189.51. Highest number of pods per plant was recorded by the cluster IX (189.51) whereas lowest was recorded by cluster VIII (113.58). The general mean value (143.15) was exceeded by 5 clusters. Individual pod weight ranged from 0.32 to 0.54 g. Maximum weight was observed in
cluster VIII (0.54 g) whereas minimum weight was observed in cluster II (0.32 g). Mean weight of cluster IV was similar to general mean value (0.41 g) and 5 clusters exceeded the general mean value.
A range of 4.83 to 5.27cm was observed with a general mean of 5.08cm for pod length. Maximum pod length was observed in cluster IV (5.27 cm) whereas minimum pod length was observed in cluster XI (4.83 cm). Six clusters exceeded the general mean value. Highest number of seeds per pod was recorded in the cluster VIII (7.79) whereas lowest was recorded in the cluster VII (7.28). Five clusters showed more number of seeds per pod than the general mean value (7.52).
Maximum 100 seed weight was recorded by the cluster VIII (3.67 g) whereas minimum weight was registered by the cluster IX (3.10 g). Six clusters exceeded the general mean value (3.32).Maximum shelling percentage was observed in cluster VIII (45.06 %) whereas minimum value was recorded by the cluster VI (32.18 %). Shelling percentage in 7 clusters was higher than the general mean value (41.13 %).
Maximum endosperm percentage was observed in cluster V (41.73 %) whereas minimum value was recorded by the cluster IV (39.12%). Five clusters exceeded the general mean value (40.50%).Maximum gum percentage was observed in genotype cluster V (39.48 %) whereas minimum value was recorded by the cluster IV (36.88%). The general mean value (38.25 %) was exceeded by 5 clusters.
Maximum pod yield per plant was observed in cluster X (69.82 g) whereas minimum pod yield per plant was observed in cluster VI (42.93 g). Six clusters recorded more pod yield per plant than the general mean value. Maximum seed yield per plant was recorded in cluster.
IX (28.26 g) whereas minimum seed yield per plant observed in cluster VI (13.65 g). Out of 12 clusters 7 clusters showed more seed yield per plant than the general mean value.
Critical analysis of cluster means for different characters indicated that the genotypes of cluster VI wereearly in flowering, the early maturing genotypes are in cluster XII, cluster V included dwarf genotypes with high endosperm percentage and gum percentage, the genotypes of cluster IV had more number of branches with high pod length, cluster IX included genotypes with more number of clusters per plant, more number of pods per plant and high seed yield per plant, cluster XI included genotypes with more number of pods per cluster, the genotypes with high shelling percentage, high pod weight, more number of seeds per pod and high 100 seed weight were grouped in cluster VIII and the genotypes with high pod yield per plant are in cluster X.
The D2 analysis revealed that cluster bean genotypes exhibited considerable diversity and all were grouped into 12 clusters. The genotypes originated from different ecogeographical regions were grouped together in the same cluster which suggested that there was no correlation between geographic diversity and genetic diversity. The characters viz., days to maturity, number of branches per plant, pod yield per plant, shelling percentage, number of seeds per pod and seed yield per plant contributed maximum towards diversity. The maximum inter-cluster distance was recorded between cluster IX and cluster XI, while the minimum inter-cluster distance was found between cluster II and cluster III. Inter-cluster distances were higher than intracluster distances which indicated the existence of substantial diversity among the genotypes. Selection of parents for crossing from divergent clusters may result in heterotic expression for yield and quality traits.
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