水稻籽粒硝态氮和铵态氮积累特性及氮肥调控研究

选用5个粳稻品种，通过田间和盆栽试验，分析水稻籽粒中硝态氮和铵态氮含量的品种间差异和籽粒中分布特点、灌浆过程中积累动态变化及其与施氮量和谷氨酰胺合成酶活性间的关系。结果表明，精米中硝态氮和铵态氮含量品种间有显著差异，铵态氮含量高于硝态氮；硝态氮和铵态氮主要分布在籽粒的米糠层里，在籽粒中呈由外到内逐渐降低的变化趋势；随着施氮量的增加，精米中硝态氮和铵态氮含量都大幅度增加，增幅高达114.1%~203.0%，但增加的幅度因品种不同而异；随灌浆进程的推进，籽粒硝态氮含量逐渐增多直至成熟，但硝态氮的日积累量和铵态氮含量随灌浆进程逐渐上升，达到峰值后又逐渐下降，呈单峰曲线变化，抽穗后25 d达到峰值，硝态氮含量高的品种日积累量显著大于含量低的品种，铵态氮含量高的品种灌浆前期积累量少于含量低的品种，而灌浆后期的积累量高于含量低的品种；籽粒谷氨酰胺合成酶活性与硝态氮和铵态氮含量及硝态氮日积累量间均呈显著或极显著正相关。

Study on Accumulation Characteristics of Nitrate-N and Ammonia-N in Grain of Rice and Regulation of N-fertilizer

Based on the field and pot culture experiment of five japonica rice varieties, the content and distribution character of ni-trate-N and ammonia-N in the endosperm, their variable trend during the grain filling period and the correlations of N-fertilizer with the enzyme activity of GS among different varieties were analyzed. The results indicated that there was a difference between nitrate-N and ammonia-N content in the mature grain among the rice varieties. The content of ammonia-N is higher than nitrate-N, which both mainly located in rice bran and showed a decline trend from outside to inside. Increasing the N-fertilizer amount led to the increase in the nitrate-N and ammonia-N level by 114.1%~203.0% depending on different varieties; As application of N-fertilizer level raised, each content showed a significant growth. During the filling period, the nitrate-N content in endosperm kept raising until the mature stage, while the accumulation amount of nitrate-N and the content of ammonia-N showed a unimodal curve trend with peak value ap-pearring at the 25th day after heading. Comparing with low nitrate-N content varieties, the daily average growth of nitrate-N was ex-tremely higher than the high content varieties. However, the daily average growth of ammonia-N was lower than the high ammonia-N content varieties at early grain filling stage, but higher at late stage than the low Ammonia-N content varieties. The enzyme activity of GS showed significant difference among different variaties at each stage, having a outstanding positive linear correlation to the content and accumulation rate of ammonia-N and nitrate-N.