EFFECT OF NITROGEN APPLICATION AT THE FLOWERING STAGE ON THE QUALITY OF SOYBEAN SEEDS

Application of nitrogen (N) fertilizer at the flowering stage changed the contents of storage compounds in seeds of Soybean (Glycine max L. cvs Enrei and Tamahomare). The effects of the N application on the mat uration of soybean seeds were examined by comparing changes in the con tents of amino acids, sugars, water, protein, and oil in seeds from N- dressed plants (NDS) with those from undressed plants (UDS) during mat uration. The application resulted in a decrease of contents of total a nd some amino acids (glutamine and asparagine) in developing seeds exc ept for at the early maturation stage and in a decreased protein conte nt of mature seeds. On the other hand, the N application led to faster accumulation of oil in developing seeds and to an increased oil conte nt of mature seeds. Based on these results, it was concluded that the N application at the flowering stage changed the composition of solute s imported by developing seeds and resulted in variations in the conte nts of storage compounds. The results indicate that it is possible to improve seed quality by fine control of N application.