氮高效利用基因型水稻生育后期氮素分配与转运特性

选择前期筛选出的氮高效利用基因型水稻为试验材料,以低效利用基因型为对照,采用土培试验,在低氮(100 mg·kg^-1)和正常施氮(200 mg·kg^-1)下,研究了高效和低效基因型水稻生育后期不同器官的氮素分配量、转运量和转运效率差异.结果表明: 与低效基因型水稻相比,高效基因型在低氮条件下,仍能保持较高的产量和氮素利用效率,其产量为低效基因型的1.75倍,氮肥利用率高达50.9%,而低效基因型仅为36.4%.与正常施氮相比,低氮更有利于提高氮素在高效基因型穗部的分配量,穗部积累量在扬花期、灌浆期和成熟期分别增加了34.2%、2.5%和0.5%,而低效基因型在灌浆期和成熟期却分别降低了23.5%和15.6%.不同施氮水平下,氮素在高效基因型不同器官的分配比例为扬花期:叶＞茎鞘＞根＞穗,灌浆期:穗＞叶＞茎鞘＞根,成熟期:穗＞茎鞘＞叶＞根,随着生育期的推进,穗部的分配比例明显增加.在低氮和正常施氮下,高效基因型氮素转运量表现为叶＞茎鞘＞根,而低效基因型表现为茎鞘＞叶＞根;高效基因型氮素转运效率分别为60.8%、60.3%,分别为低效基因型的1.67、155倍.因此,高效基因型抽穗后叶片较高的转运效率为籽粒的灌浆结实奠定了良好基础.

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

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·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 60.8%, 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.