不同氮素利用效率基因型水稻氮素积累与转移的特性

选用氮素利用高效型和低效型具有代表性的12个粳稻基因型, 研究水稻氮素积累、转移特性的差异及其与氮素利用效率的相互关系。结果表明, 有效分蘖临界叶龄(N-n)、抽穗和成熟期, 氮高效类型水稻的氮素积累量极显著高于氮低效类型, 而拔节期差异不明显。水稻氮素的阶段性积累量, 除(N-n)至拔节阶段, 氮高效类型水稻极显著低于氮低效类型外, 其余各阶段氮高效类型水稻的氮积累量均极显著高于氮低效类型。水稻氮素的阶段性积累率, 移栽至(N-n)和(N-n)至拔节阶段氮低效类型水稻显著大于氮高效类型, 而在拔节至抽穗和抽穗至成熟阶段则表现出相反的趋势。抽穗前的氮素转移量和转移率, 氮高效类型水稻显著或极显著大于氮低效类型, 而抽穗前氮对籽粒的贡献率, 氮高效类型极显著低于氮低效类型。氮高效类型水稻具有在(N-n)前氮素适度积累, (N-n)后至抽穗阶段, 氮素的有效积累高而无效积累弱的特点。因此至抽穗期, 氮高效类型水稻的氮素积累量大于氮低效类型, 具有较高的氮素转移量和转移率。但由于氮高效类型水稻在抽穗以后仍具有较强的氮素积累能力, 因此其抽穗前氮对籽粒的贡献率相对低于氮低效类型。

Characteristics of N Accumulation and Translocation in Rice Genotypes with Different N Use Efficiencies

N is yet the most important and largest input required in rice production although over use of N causes so many environment problems. N use efficiency is varied in different rice genotypes. Therefore it is necessary to identify the physiological mechanism of N absorption and utilization in different rice genotypes in order to increase N use efficiency through rice cultivar improvement. In this research, field experiment with 225 kg ha^-1 N fertilizer application and twelve rice genotypes (6 N-efficient and 6 N-low-efficient ) selected from 120 rice cultivars grown in Yangzhou during 2004 and 2005 were carried out in 2006 on the farm of Yangzhou University, Jiangsu province, China. Relationship between N use efficiency and indexes of rice N accumulation and translocation was analyzed. At the three growth stages including critical stage of productive tillering, heading, and maturing, the amount of N accumulation of N-efficient rice was obviously higher than that of N-low-efficient genotypes while at the stage of elongating, there was no significant difference in N accumulation between the two rice genotypes. In order to analyze the N accumulation progress of rice genotypes with different N use efficiency, the growth was also divided into four phases including from transplanting to critical stage of productive tillering, from critical stage of productive tillering to elongating, from elongating to heading and from heading to maturing. Results revealed that the amount of N accumulation of N-efficient genotypes was significantly higher than that of N-low-efficient genotypes during all growth phases except the phase from critical stage of productive tillering to elongating, at which the amount of N accumulation of N-efficient genotypes was significantly lower than that of N-low-efficient genotypes. The percentage in N accumulation of N-efficient genotypes was higher than that of N-low-efficient genotypes during the growth phases from elongating to heading and from heading to maturing while it showed the reversed trend during the phases from transplanting to critical stage of productive tillering and from the critical stage of productive tillering to elongating. The amount and the efficiency of N translocation before heading were obviously higher in N-efficient genotypes than those in N-low-efficient genotypes. On the contrary, the contribution rate of transferred N to the total N of rice grain at maturity was significantly lower in N-efficient genotypes than that in N-low-efficient genotypes. For N efficient genotypes, the amount of N accumulation before the critical stage of productive tillering was modest. And during the phase from the critical stage of productive tillering to heading, its N accumulation of usefulness was large while the N accumulation of uselessness was few. Therefore, till the stage of rice heading, the amount of N accumulation of N-efficient genotypes was obviously higher than that of N-low-efficient genotypes. And the amount and the efficiency of N translocation before heading of N-efficient genotypes were also higher than that of N-low-efficient genotypes. Because of the strong ability of N accumulation of N-efficient genotypes after heading, its contribution rate of transferred N to the total N of rice grain at maturity was relatively lower than that of N-low-efficient genotypes before heading.