CHARACTER ASSOCIATION, SELECTION INDICES AND GENETIC DIVERGENCE IN GROUNDNUT (Arachis hypogaea L.)
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Date
2011-06
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jau,junagadh
Abstract
An investigation was carried out using 108 genotypes of groundnut to find out the genetic variability, correlation coefficients, path coefficients, selection indices and genetic divergence. The material was evaluated in a randomized block design with three replications at the Main Oilseeds Research Station, J. A. U., Junagadh during kharif 2010. The observations were recorded on 19 characters viz., days to 50% flowering, days to maturity, plant height (cm), number of primary branches per plant, number of secondary branches per plant, number of pods per plant, kernel yield per plant (g), pod yield per plant (g), haulm yield per plant (g), number of pegs per plant, number of mature pods per plant, sound mature kernels (%), 100-pod weight (g), 100-kernel weight (g), shelling out-turn (%), oil content (%), protein content (%), biological yield per plant (g) and harvest index (%).
Analysis of variance revealed significant differences among the genotypes for all the 19 characters studied. The highest range of variation was observed for harvest index followed by biological yield per plant, haulm yield per plant, plant height, sound mature kernels, 100-pod weight, days to maturity, shelling out-turn and number of secondary branches per plant. The highest genotypic coefficient of variation was observed for number of secondary branches per plant followed by haulm yield per plant, harvest index, number of mature pods per plant, number of pegs per plant, number of primary branches per plant, number of pods per plant, kernel yield per plant, plant height and biological yield per plant.
The values were observed to be moderate for pod yield per plant,
100-kernel weight, 100-pod weight, sound mature kernels and days to maturity. High heritability along with high genetic advance was observed for number of primary branches per plants, number of secondary branches per plants, number of pods per plant, haulm yield per plant, number of pegs per plant, number of mature pods per plant, biological yield per plant and harvest index.
The values of genotypic correlation were higher than their corresponding phenotypic correlations in the present study. The pod yield per plant exhibited significant positive association with number of pods per plant, kernel yield per plant, number of pegs per plant, number of mature pods per plant, 100-pod weight, 100-kernel weight and harvest index at both genotypic and phenotypic levels, while pod yield per plant exhibited highly significant and negative correlation with days to maturity, plant height, number of secondary branches per plant and haulm yield per plant at both the genotypic and phenotypic levels. The pod yield per plant also showed positive and highly significant correlation with days to 50% flowering and shelling out-turn at genotypic level.
The analysis of path coefficient was observed the highest positive direct effects for days to 50% flowering, number of pods per plant, kernel yield per plant, haulm yield per plant and harvest index towards pod yield per plant. The indirect effects through days to 50% flowering, numbers of pegs per plant and harvest index were higher and positive for most of the characters. Based on correlation and path analysis, days to 50% flowering, number of pegs per plant, harvest index, kernel yield per plant, number of pods per plant, number of mature pods per plant, 100-pod weight and 100-kernel weight identified as the most important components of pod yield.
The selection indices forming 63 combinations involving pod yield and five yield components were constructed using the discriminant function technique. In a single character index, the maximum efficiency was exhibited by harvest index followed by haulm yield per plant, number of pods per plant and kernel yield per plant. The efficiency of selection increased with the inclusion of more number of characters in the index. The highest relative efficiency was exhibited by a selection index involving five component characters viz., pod yield per plant, days to 50% flowering, number of pods per plant, kernel yield per plant and harvest index followed by an index based on four characters viz., pod yield per plant, number of pods per plant, kernel yield per plant and harvest index.
The 108 genotypes were grouped into 13 clusters by Mahalanobis’s
D2-statistic. The clustering pattern of the genotypes did not confirm to the geographical distribution. The maximum inter-cluster distance was found between clusters VIII and XII followed by that between clusters IV and XII, VIII and XI, XI and XIII, XII and XIII, V and VIII, IV and XI and VI and XII. The cluster XI was superior for haulm yield per plant, number of pegs per plant, 100-pod weight and protein content, while Cluster I was the best for number of pods per plant, number of mature pods per plant and harvest index. Cluster XII was good for plant height and sound mature kernel. The cluster II was good for pod yield per plant and kernel yield per plant. The cluster XIII was good for number of primary branches per plant and secondary branches per plant. The cluster IV was good for days to 50% flowering, while the cluster X had greater mean for days to maturity. The cluster VI was good for shelling out-turn. The cluster IX had higher mean for oil content and the cluster V was good for 100-kernel weight. Therefore, in the present investigation, bases on high yielding genotypes and large inter-cluster distances, it is advisable to attempt crossing of the genotypes from cluster XI with the genotypes of cluster XII and I, which may lead to broad spectrum of favourable genetic variability for yield improvement in groundnut.
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botany