施氮量对小麦籽粒灌浆的影响及其生理机制

为探明施氮量对小麦籽粒灌浆的影响及其生理机制，以当地高产小麦品种扬麦16和宁麦13为材料，设置120 kg·hm^-2(LN)、180 kg·hm^-2(MN)和240 kg·hm^-2(HN) 3个施氮量处理，分析了在不同施氮量下，强、弱势籽粒灌浆特征与籽粒中蔗糖-淀粉代谢途径中关键酶活性的变化。结果表明，两个小麦品种的籽粒产量随着施氮量的增加而增加，但在MN与HN处理间差异不显著。氮肥偏生产力随着氮肥用量的增加而显著降低。与LN处理相比，MN处理提高了扬麦16弱势粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(SSS)和淀粉分支酶(SBE)的活性、弱势粒灌浆速率和粒重；HN则降低了扬麦16弱势粒中被测酶的活性和粒重。宁麦13弱势粒中AGPase、SSS和SBE活性、弱势粒灌浆速率和粒重则随施氮量的增加而降低。施氮量对两个小麦品种强势粒中被测酶活性、籽粒灌浆速率和粒重无显著影响。以上结果说明施氮量主要是影响小麦弱势粒的灌浆，且在品种间存在差异；施用氮肥后弱势粒灌浆速率和粒重的增加或降低与籽粒中蔗糖-淀粉代谢途径中关键酶活性的增强或降低密切相关；在地力较好条件下，施氮量为180 kg·hm^-2时就可以获得高产与氮肥高效利用的效果。

Effect of Nitrogen on Grain Filling of Wheat and Its Physiological Mechanism

In order to know the influence and physiological mechanism of nitrogen (N) application on wheat grain filling,two local high-yielding wheat varieties,Yangmai 16 and Ningmai 13,were grown in field,and 120 kg·hm^-2 (LN),180 kg·hm^-2 (MN) and 240 kg·hm^-2 (HN) were applied during the whole wheat growing season. Grain filling level of superior and inferior grains and changes in activities of key enzymes involved in sucrose-to-starch conversion in grains were determined. The results showed that grain yield was increased with the increase of N level,but it exhibited no significant difference between MN and HN. Nitrogen partial factor (grain yield/N amount) was significantly decreased with the increase of N level. When compared with LN,the activities of adenosine diphosphoglucose pyrophosphorylase (AGPase),soluble starch synthase (SSS) and starch branching enzyme (SBE),grain filling rate and grain weight of inferior grains for Yangmai 16 increased with MN treatment,while decreased with HN treatment.The enzymatic activities,grain filling rate and grain weight of inferior grain were decreased with the increase of N level for Ningmai 13. No significant effect of N level on the grain filling of superior grains was detected. The results indicated that N level mainly regulated grain filling of inferior grains,and the regulation varied with varieties.The grain filling rate and grain weight of inferior grains are closely associated with the enhancement or reduction in activities of the key enzymes in sucrose-to-starch conversion in these grains. Under good soil fertility,high yield and N use efficiency could be achieved when N level was 180 kg·hm^-2.