[Characteristics of distribution and transportation of rice genotype with high nitrogen utilization efficiency at the late growth stage].

ABSTRACT

Taking a high nitrogen utilization efficiency rice genotype (NUE(H)) as test material and a low nitrogen utilization efficiency genotype (NUE(L)) as control, a pot experiment was carried out with nitrogen treatments of 100 (low) and 200 mg x kg(-1) (normal), to analyze the differences in nitrogen accumulation distribution, translocation and transport efficiency between the two genotypes. The results showed that NUE(H) could still maintain a high yield and a high nitrogen utilization efficiency at the low rate of nitrogen fertilization, with the grain yield being 1.75 times of that of NUE(L), and the nitrogen recovery efficiency of 50.9% compared with 36.4% for NUE(L). Compared to the normal nitrogen fertilization rate, the low nitrogen fertilization rate promoted the nitrogen accumulation by 34.2%, 2.5% and 0.5% in NUE(H) at the flowering, filling and mature stages, while decreased by 23.5% and 15.6% in NUE(L) at filling and mature stages, respectively. Nitrogen accumulation distribution in organs of NUE(H) was in the order of leaf > stem > root > spike, spike > leaf > stem > root, and spike > stem > leaf > root at the flowering, filling and mature stages, respectively. With the advancement of growth period, the nitrogen accumulation in spike increased obviously. At the two nitrogen fertilization rates, nitrogen transfer was ordered as leaf > stem > root for NUE(H), and stem > leaf > root for NUE(L), and nitrogen transfer efficiencies of NUE(H) were 50.8%, 60.3%, which were as 1.67 and 1.55 times as that of NUE(L), respectively. It could be concluded that the higher nitrogen transport efficiency of NUE(H) leaves laid a good foundation for the construction of grain after heading.