GENETIC DIVERSITY AND SELECTION INDICES IN CASTOR (Ricinus communisL.) 2425
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Date
2017-09
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JAU,JUNAGADH
Abstract
Key words:Castor, Diversity, Selection indices, Variability
A trial was conducted to assess variability, diversity and selection indices for seed yield and its attributes with a set of 64 genotypes of castor (Ricinus communis L.) at Main Oilseeds Research Station, Junagadh Agricultural University, Junagadh during Kharif 2016-17. Total12 quantitative characters were studied viz., days to 50% flowering of main raceme, days to maturity of main raceme, number of nodes up to main raceme, plant height up to main raceme, total length of main raceme, effective length of main raceme, number of capsules on main raceme, number of effective branches per plant, seed yield per plant, 100-seed weight, oil content and shelling out turn.
The analysis of variance revealed highly significant differences among the mean square due to genotypes for all the twelve characters studied. A wide range of variation was observed for important yield components. High genotypic and phenotypic coefficient of variations, high heritability coupled with high genetic advance as per cent of mean was observed for all the characters except days to 50% flowering of main raceme, days to maturity of main raceme, oil content and shelling out turn.
The genetic diversity analysis grouped the genotypes in ten clusters suggested the presence of considerable genetic diversity among the 64 genotypes studied. The clustering pattern indicated that geographic diversity was not associated with genetic diversity. The analysis of per cent contribution of various characters towards the expression of total genetic divergence indicated that seed yield per plantcontributed the maximum towards total genetic divergence followed by 100-seed weight, plant height up to main raceme, number of capsules on main raceme, total length of main raceme, number of effective branches per plant, oil content, days to 50% flowering of main raceme, effective length of main raceme. Based on the maximum genetic distance, it is advisable to attempt crossing of the genotypes from cluster X with the genotypes of cluster VIII, II and VII, which may lead to the generation of broad spectrum of favourable genetic variability for yield improvement in castor.
The discriminant function indicated that selection based on multiple characters had higher genetic gain and relative efficiency over straight selection for seed yield per plant alone. There was an increase in genetic gain and relative efficiency with inclusion of an additional trait in the character combination.
Selection index involving seed yield per plant, effective length of main raceme, number of capsules on main raceme, number of effective branches per plant and shelling out turn could be advantageously exploited in the castor breeding programmes.
On the basis of overall studies, it can be concluded that due weightage should be given to seed yield per plant,number of capsules on main raceme, effective length of main raceme, shelling out turn and number of effective branches per plant while imposing selection for genetic improvement of seed yield in castor.Hybridization among diverse genotypes followed by pedigree method of selection would be beneficial to isolate transgressive segregants with high seed yield.
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PLANT BREEDING