GENETIC DIVERGENCE FOR QUALITY TRAITS IN RICE (Oryza sativa L.)
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Date
2015
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
In the present investigation, fifty genotypes of rice (Oryza sativa L.) were evaluated to study the genetic diversity present in the experimental material for selection of the diverse parents, to estimate the genetic parameters among the genotypes for yield and quality traits and to find extent of association between the quality, yield and its component characters including the direct and indirect effects. The experiment was laid out in a Randomized Block Design with three replications at Andhra Pradesh Rice Research Institute and Regional Agricultural Research Station, Maruteru during kharif, 2012.
The analysis of variance revealed significant differences among the genotypes for all the characters studied indicating wide variability among genotypes. The genotypic coefficients of variation for all the characters studied were lesser than the phenotypic coefficients of variation indicating the modifying effect of the environment in association with the characters at genotypic level. The results of genetic parameters revealed that moderate to high GCV, PCV coupled with high heritability and moderate to high genetic advance as percent of mean for plant height, days to 50% flowering, grain yield, kernel breadth after cooking, elongation ratio, water uptake, volume expansion ratio, alkali spreading value and gel consistency.
The genetic divergence was high and 50 rice genotypes were grouped into 8 clusters. Out of eight clusters, cluster II was the largest comprising of 19 genotypes followed by cluster I and cluster III with 13 genotypes, cluster IV, V, VI, VII and VIII with only one genotype each. The pattern of distribution of genotypes into various clusters was at random indicating that geographical and genetic diversity were not related. The pattern of group constellations indicated significant variability among the genotypes.
From the inter cluster D2 values of eight clusters, it can be seen that the highest divergence occurred between cluster IV and cluster V (547.97) followed by cluster V and cluster VII (486.66), cluster I and cluster IV (407.07) and cluster III and cluster VIII (392.71) suggesting that the crosses involving lines from these clusters would give wider and desirable recombinations.
The characters days to 50% flowering, test weight, water up take and gel consistency together contributed 82.12 % towards total divergence. Hence these characters should be taken into consideration while selecting parents for hybridization. The cluster I is having highest mean value for grain yield per plant, alkali values, cluster II for kernel length, L/B ratio; cluster III for test weight, kernel length after cooking; cluster IV for panicle length; cluster V for head rice recovery, elongation ratio, volume expansion ratio, gel consistency, amylose content; cluster VI for number of panicles per plant, days to 50% flowering, hulling, milling; cluster VII for kernel breadth, water uptake; cluster VIII for plant height and kernel breadth after cooking. The genotypes from these clusters having high mean values may be directly used for adaptation or may be used as parents in future hybridization programme.
It is observed that no cluster contained at least one genotype with all the desirable traits, which ruled out the possibility of selecting directly one genotype for immediate use. Therefore, hybridization between the selected genotypes from divergent clusters is essential to judiciously combine all the targeted traits.
Character association studies indicated significant positive association of days to 50% flowering, number of panicles per plant, test weight, hulling, milling, head rice recovery, kernel length, kernel L/B ratio, kernel length after cooking, volume expansion ratio with grain yield per plant. Hence, selection of these traits would be more effective to bring simultaneous improvement in grain yield and quality and to evolve high yielding varieties in rice with acceptable grain quality.
Among quality parameters significant positive association was observed between hulling with milling percent, head rice recovery, elongation ratio and alkali spreading value; kernel length with kernel breadth, kernel L/B ratio, kernel length after cooking, amylose content, alkali spreading value; volume expansion ratio with elongation ratio, kernel length after cooking, head rice recovery and gel consistency and amylose content with kernel breadth.
Path coefficient analysis revealed that days to 50% flowering, panicle length, number of panicles per plant, test weight, kernel length, kernel breadth, kernel breadth after cooking, elongation ratio, volume expansion ratio, amylose content, gel consistency showed positive direct effect on grain yield. These parameters also manifested significant positive correlation with grain yield per plant at both phenotypic and genotypic level. Hence, these traits may be given prime importance for the direct improvement of grain yield and quality.
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D5186
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