Effect of Yield and Its Components on Seed Oil Content, Protein Content and Fatty Acid Composition in Soybean (Glycine max L.)

This research was conducted to study the effect of yield, and its components on seed oil content and its quality. Twenty soybean varieties were employed in a randomized complete block arrangement with three replications at the Agricultural Experiment Station, College of Agriculture, University of Tehran, Karaj, Iran. A total of 25 traits related to vegetative and reproductive growth, yield component and oil as well as fatty acid contents were analysied. In estimation of simple correlation between traits, oleic acid percentage was positively correlated with seed length with oil yield while negatively correlated with linoleic and linolenic acid contents (percentages). Linolenic acid showed negative correlation with plant yield and linoleic acid percentage but was positively correlated with palmitic acid percentage. In stepwise regression analysis, using oil yield as dependent variable, 3 variables entered into the regression model which accounted for 91% of oil yield variation. In path analysis, stearic acid percentage and number of pods/plant had high positive direct effects on oil yield. PCA resulted in six factors that accounted for 79.6% of total variation. Results of factor analysis suggested that seed size traits could be used as selection criteria in breeding programs to improve seed oleic acid percentage.