Uptake and utilization of different nitrogen forms in erect panicle japonica rice cultivar

ABSTRACT The response of rice to nitrogen (N) was compared between three rice cultivars and three N treatments: 1:0, 0:1, and 1:1 NH4+:NO3？. The three rice cultivars used were: Shennong1401 (SN1401, erect panicle rice cultivar) and Habataki and Sasanishiki (curved panicle rice cultivars). At the booting stage, higher gene expression and enzyme activity associated with N metabolism of rice in the including-NO3？ solutions effected the secondary assimilation of N metabolism, and ultimately increased grain development. During the tillering stage, lower NO3？ uptake rates and glutamine synthetase and NADH-dependent glutamate synthase activity in Habataki and Sasanishiki under the NO3？ treatments resulted in lower effective panicle number per plant. However, no significant differences were observed in the grain yield per plant of SN1401 between NH4+ and NO3？ treatments. Our results indicate that the erect panicle rice cultivar can grow better under the including-NO3？ treatment