Abstract

This study was performed to identify genetic diversity of soybean lines, to determine the best parents for crossing to improve the yield and to find out more effective genetic characteristics in Khoramabad, Lorestan province, Iran. Field experiments were conducted in a randomized complete block design. Our present results implied that the lines had significant effects for all the studied traits except days taken to physiological maturity, days taken to full maturity and oil percentage. The results of correlation coefficients showed that grain yield positively correlated with number of grains per pod, harvest index and seed filling rate at the 1% possibility level and oil percentage at the 5% possibility level. The step-wise regression results illustrated that grain filling rate, grain filling duration and days taken to physiological maturity had significant effects on the grain yield variations. Grain filling rate and grain filling duration also justified variations of oil yield. On the base of the regression analysis, grain filling rate and period and days taken to physiological maturity were the most important traits for improving the seed and oil yields of soybean lines. Path analysis indicated that grain filling rate and period had a significant positive effect on seed yield. Moreover, grain filling rate also had a significant positive effect on oil yield. The results of path analysis and regression analysis suggested that grain filling rate was the effective trait to improve the seed and oil yields of soybean lines.