Relationships of grain oil and protein contents with some important agronomic traits in soybean using path and canonical correlation analyses

To determine relationships between seed oil and protein contents with some important agronomic traits, 364 soybean genotypes were evaluated using an augmented design in Seed and Plant Improvement Institute, Karaj, Iran, during 2004 growing season. Most agronomic traits had significant negative correlation with seed oil content, except number of seed.pod-1. However, most agronomic traits had highly significant positive correlation (p<0.01) with seed protein content, except seed oil content and number of seed.pod-1. Results of stepwise regression and path analyses showed that seed protein content and days to beginning of flowering had direct negative effect, and 100 grain weight had direct positive effect on grain oil content. Oil content and biomass also had direct negative effect, and 100 grain weight had direct positive effect on grain protein content. Canonical correlation analysis for seed yield and seed quality variables led to introduction of two pairs of variables. The first pairs was named "grain yield and number of grain.plant-1 " and "grain oil content" and the second pairs was named "grain yield and number of pod.plant-1 " and "grain protein content", respectively.