QUANTITATIVE GENETIC ANALYSIS OF YIELD COMPONENTS AND GRAIN YIELD FOR SOYBEAN CULTIVARS

Grain yield components are important indicators of the grain yield level of soybean (Glycine max (L.) Merrill). The objective of this study was to estimate the efficiency and reliability of soybean yield components as selection criteria for grain yield and to evaluate agronomic value of domestic soybean cultivars as potential parents in hybridizations for further genetic improvement of soybean grain yield. Trials were conducted on the experimental field of The Agricultural Institute Osijek over five years, from 1996 to 2000. The study involved 14 domestic soybean cultivars (cv.) ranging maturity groups 0 to II. Mean values, coefficient of variation and broad-sense heritability were calculated for grain yield and the following yield components: plant height (cm), number of plant-1 fertile nodes, plant-1 pod number, plant-1 seed number, plant-1 of seeds weight (g), plant-1 harvest index (%) and 1000 seed weight (g). Path-coefficient analysis was applied to determine the effects of analyzed yield components on grain yield. The obtained results of quantitative genetic analysis showed that components weight and number of plant-1 seeds had the lowest variability, the highest heritability and the highest positive direct effect on grain yield among analyzed yield components. Among the tested cultivars, cv. Ika had the highest mean for both yield components. The obtained results suggest that the indirect selection for higher soybean grain yield using the yield components, seed weight and number of seeds per plant was more efficient and more reliable than selection over the other yield components. Among the tested cultivars, cv. Ika appeared to be the most suitable as a parent in future hybridizations to achieve further genetic advance in soybean grain yield