Simultaneous Selection for Seed Yield and Other Agronomic Traits in Promising Advanced Lines of Soybean

Soybean is one of the most important oilseeds and the selection of high-yielding genotypes is especially important. Also, study on relationships between yield and other agronomic traits will improve the efficiency of a breeding program with appropriate selection criteria. Therfore, the objectives of this research were to selection of new soybean line and finding interrelationships among traits.

In this study, 15 promising advanced lines along with two cultivars Saba and Amir were evaluated in a randomized complete block design with three replications in agriculture research station of Gorgan during the two growing seasons (2020-2021). The phonological, morphological characteristics and yield and its components including days to flowering starting, days to podding starting, days to end of flowering, days to physiological maturity, plant height, branching height, number of nodes, number of sub-branches, number of pods in the main branch, number of pods in sub-branches, number of pods per plant, number of seeds per pod, number of seeds per plant, thousand seed weight and seed yield were measured. In this study, the selection index of ideal genotype (SIIG) and factor analysis were used to select soybean genotypes and study the relationships between traits.

Based on the SIIG index, the genotypes: G15, G5, G12, G1, G4, G13, and G11 with the highest SIIG values (0.645, 0.638, 0.615, 0.600, 0.600, 0.544, and 0.520 respectively) were the best genotypes.  On the other hand, G17, G16, G7, G10, and G9 genotypes with the least amount of SIIG value (0.309, 0.319, 0.376, 0.384, and 0.386 respectively) were the weakest genotypes for most studied traits. The lines of G4, G5, and G13 with high SIIG value and seed yield were recognized as superior genotypes from the point of yield and other agronomic traits. Also, the results of factor analysis indicated a positive relationship between number of seeds per pod and early maturity with seed yield.

Generally, the results indicated that the lines: G4, G5 and G13 were superior genotypes from the point of yield and other agronomic traits. Also, the traits of number of seeds per pod and early maturity could be used as suitable selection criterions for increasing seed yield in soybean breeding programs in Golestan province.