Effect of basal side-dressing of various types of coated urea fertilizer on shoot growth, yield components and seed composition of soybean (Glycine max(L.) Merr.)

Abstract

Effect of basal side-dressing ORIGINAL ARTICLE Effect of basal side-dressing of various types of coated urea fertilizer on shoot growth, yield components and seed composition of soybean (Glycine max (L.) Merr.) Yoshihiko AbstractApplication of nitrogen (N) fertilizer at different times affected the shoot characters, yield components and seed composition of the soybean cultivar "Enrei" and its non-nodulating line "En1282". Soybean plants were cultivated using various types of coated urea fertilizers for controlled released of N. The control treatment consisted of basal side-dressing of readily available mixed fertilizer, which contained 1.6 g N m . Various types of coated urea fertilizers were applied with basal sidedressing of 6 g N m −2 in addition to the mixed fertilizer. The types of coated urea fertilizers were as follows: linear release types CU70, CU100 and CU140, and sigmoid release types CUS80, CUS100 and CUS120. A major part of the N from CU70 and CU100 was released before the middle-stage of growth (beginning of pod stage), whereas CUS80 and CUS100 released N at approximately the middle-stage and CUS120 released N after the mid-stage. CU140 fertilizer is a uniform release type throughout the growth period. At the middle stage of growth, the chlorophyll content (leaf color) of En1282 was high with CU100 treatment, while the CUS100 treatment led to high chlorophyll content during the filling period. Leaf chlorophyll content of Enrei tended to increase with the CUS120 treatment during the filling period. The N 2 fixation activity of nodulating Enrei, which was estimated using the relative ureide method, significantly decreased in the CU70, CU100 and CU140 treatments compared with the control at the flowering stage. At the beginning of the pod stage, treatment with CUS120 tended to lead to a higher N 2 fixation activity than the control, whereas the CUS80 and CUS100 treatments depressed the N 2 fixation activity during the seed filling period. The amount of N that accumulated in the shoots in all the coated urea treatments increased significantly compared with the control treatment in En1282 at the beginning of the maturity stage, whereas in Enrei it increased significantly only in CUS120 compared with the control. The yield was significantly higher in all the coated urea treatments compared with the control (49 g m ) in which N supply from the flowering period to the beginning of the pod stage resulted in the highest yield in En1282. In addition, in Enrei the seed yield increased significantly in each coated urea treatment and the largest increase was induced by CUS120 (498 g m ). In non-nodulating En1282, the amount of N released from flowering to the beginning of the pod stages showed a significant correlation with the total number of nodes, seed yield and seed weight. In nodulating Enrei, there was a significant relationship between N release from the beginning of the pod to the beginning of the maturity stages and the length of the main stem, seed yield and seed protein content. There was no signif...

Soybean Seed Production and Nitrogen Nutrition

“…Top dressing of N fertilizer sometimes gives positive effects on seed yield, but results are not consistent. Takahashi et al reported the effect of basal side-dressings of various types of controlled release nitrogen fertilizer (coated urea) on shoot growth and seed yield of soybean [73]. The yield was significantly higher in all the coated urea basal side-dressing treatments compared with control, particularly in CUS120 which releases urea from 60 to 120 days after planting with a sigmoid pattern of N release.…”