Genetic diversity studies in Yam bean [Pachyrhizus erosus (L.) Urban]
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Date
2018
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Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur)
Abstract
The present study was undertaken with thirty germplasm accessions of yam bean having different geographical origin, obtained from germplasm collections at T.C.A., Dholi, including Rajendra Misrikand-1(RM-1) and Rajendra Misrikand-2 (RM-2) released from All India Coordinated Research Project on Tuber Crops (AICRPTC), Dholi. The experiment was carried out at T.C.A., Dholi Research Farm of Dr. R.P.C.A.U., Pusa, Samastipur, Bihar, in a completely Randomised Block Design with three replications during kharif, 2017 for genetic diversity studies in Yam Bean [Pachyrhizus erosus (L.) Urban]. Data were collected for twelve characters viz., Plant height (cm), No. Of branches per plant, Days to 50% flowering, Pods per plant, Pod weight per plant (g), Pods per peduncle, Pod length (cm), No. of seeds per pod, Tuber weight (g), Dry matter (%), Tuber yield (kg/plot) and Seed yield (kg/plot).Statistical analysis carried out were, Analysis of variance, genotypic and phenotypic coefficient of variation, Heritability, Genetic advance, Correlation coefficient analysis, path analysis and Genetic diversity
Analysis of variance revealed highly significant differences among the genotypes for all the twelve characters under study. Maximum range was found for the characters like tuber weight followed by days to 50% flowering, plant height and pod weight per plant. The phenotypic coefficient of variance was greater than genotypic coefficient of variance for all the characters under study and high magnitude of PCV and GCV were observed for traits like tuber weight followed by tuber yield indicating that these traits could be used for tuber yield improvement. Characters like tuber yield, tuber weight, seed yield, pods per plant and plant height exhibited high Heritability coupled with high Genetic advance as percent of mean indicating effectiveness of selection due to preponderance of additive gene action for these traits and direct selection may be effective for these traits.
Tuber weight showed significant and positive correlation with tuber yield. Pods per plant and pod weight per plant exhibited significant and positive correlation with seed yield. Number of seeds per pod exhibited significant and positive correlation with pod length and pod weight per plant was found to have significant and positive correlation with pods per plant. Pods per plant exhibited significant and positive correlation with number of branches per plant. Such correlation indicates true relationship and thus assists in predicting tuber or seed yield. Path analysis revealed that tuber weight had high positive direct effect on tuber yield. Pods per plant and pod weight per plant were found to have high positive direct effect on seed yield. Thus these traits may be used as selection criteria.
All the thirty genotypes were grouped into 6 clusters using D2 statistics following clustering suggested by Tocher. Highest inter cluster distance was observed between cluster I and III (107.53) followed by cluster III and VI (97.61) and cluster I and II (78.54) on the basis of their genetic distances. Genotypes from these clusters may be utilised under inter varietal hybridisation programme (transgressive breeding) for getting superior recombinants.
Cluster V showed maximum cluster mean values for seed yield (0.12) and attributing characters like plant height (75.97), number of branches per plant (3.30), pods per plant (15.13), pod weight per plant (33.67), pod length (10.50) and number of seeds per pod (8.40) while cluster III showed maximum cluster mean values for tuber yield (1.88) and its attributing character like tuber weight (396.67). Therefore, selection of parents from different clusters might be done for desired traits on the basis of higher cluster mean values. Tuber yield followed by tuber weight and seed yield were having maximum contribution towards total divergence.
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