Relationship Between the Soybean (Glycine max L. Merr.) Yield Components and Seed Yield Under Irrigation Conditions

The study presents the results of a three-year experiment (2013–2015) that was carried out to determine a relationship between the soybean yield components and the seed yield under different irrigation treatments. The results indicated that the study year had the greatest effect on the number of nodes per plant (NNP), while an interaction between the irrigation and experiment year was also statistically significant. The highest average NNP was observed in 2015, being 33% higher when compared to the year 2014. The highest number of seeds per plant (NSP) was observed in 2015, being 20% and 31% higher when compared to 2013 and 2014. An abundant irrigation resulted in the highest NSP when compared to a rational and control treatment. Irrigation, study year, and their interaction did not have a statistically significant effect on the thousand seed weight (TSW) (g), but the lowest average TSW (g) was obtained in the control treatment of each study year. Regression models pertaining to the seed yield prediction in the control treatment and rational irrigation were not statistically significant. However, in the abundant irrigation, the regression model based on the TSW (g), NNP, and the NSP as the predictors provided for a statistically significant model seed yield prediction, but only the NSP was identified as a highly significant seed yield predictor.