ISSN: 0041-3216

ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 82 Number 2
Research Papers
Genetic studies for rice improvement in the humid tropics of Bay Islands. (85)
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Genotypes were found to be significantly different from each other in respect of all the characters under study. High genotypic coefficient of variance (GCV) was observed for plant height, grain density, 100-grain weight, and 100-kernel weight. The characters like plant height, number of panicles per plant, number of grains per plant, grain density, 100-grain weight, 100-kernel weight, and grain yield per plant showed high phenotypic coefficient of variance (PCV) values. Heritability estimates were high for days to 50% flowering, plant height, 100-grain weight, 100-kernel weight, grain length, grain breadth, grain length:breadth ratio, kernel length, kernel breadth, and kernel length:breadth ratio. High genetic advance (GA) with high heritability (H2) were observed for plant height, number of grains per panicle, grain density, 100-grain weight, 100-kernel weight, grain length:breadth ratio, and kernel length:breadth ratio. Grain yield showed significant positive association with plant height, number of panicles per plant, number of filled grains per panicle, grain density, 100-grain weight, and 100-kernel weight at both phenotypic and genotypic levels. Thus, selection for more number of panicles per plant, filled grains per panicle, grain density, 100-grain weight, 100-kernel weight, and grain length were deemed to be effective in improving grain yield per plant. Highest positive direct effects on grain yield per plant were observed for grain length:breadth ratio followed by grain breadth, grain density, and kernel length. Plant height, number of panicles per plant, panicle length, grain density, 100-kernel weight, grain breadth, kernel length, and kernel thickness showed positive direct effects on grain yield per plant. In such a situation, restrictions should be imposed to nullify the undesirable indirect effects to make use of the direct effects. The correlation coefficients between grain yield and direct effects of plant height and kernel grain:weight ratio did not differ considerably. A direct selection involving those characters would be more effective.
Keywords: Island ecosystem; Rice; Genetic variability; Character association; Path analysis