Studies on the Response of Nodulated Soybean to Nitrogen Fertilizer : II. On the seed quality and assimilate partitioning to seeds at different nodal position

Abstract

A glasshouse pot sand culture experiment was conducted to determine the effects of three levels of combined nitrogen-0N (0), 1N (100), 2N (200 pm) -on nitrogen nutrition, seed protein and oil content and the distribution pattern of ¹⁴C activity in the seed at different nodal position of soybean (Glycine max (L) Merr. cv. Akiyoshi). Plants were fed with ¹⁴CO₂ at the vegetative, flowering, early pod filling and late pod filling stages of growth. Nitrogen content of plant organs increased with increasing level of supplied nitrogen and declined in the vegetative organs with plant growth. Combined nitrogen had no significant effect on mean seed protein and oil content. No ¹⁴C activity was detected in seeds of plants fed at the vegetative and flowering stages. More ¹⁴C was retained in seeds of plants fed at late pod filling stage than fed at early pod filling stage. Combined nitrogen had no remarkable effect on the amount and distribution pattern of ¹⁴C. Activity of ¹⁴C in seeds was in the order of secondary branches<main stem<primary branches. Excessive combined nitrogen had little effects on the seed yield and sysnthesis of protein and oil components in seeds.