Abstract: To study the effects of nitrogen and potassium application on the amylose content,total starch content and the activities of starch synthase in rice grain during grain filling,a two-factor pot experiment was conducted using a hybrid rice combination B You 827 as material. In addition,the effects of nitrogen and potassium on the grain starch accumulation and the changes in starch synthase activities and their relationships during grain filling were further investigated. The amylose content of rice grain increased within 20 days after flowering,and then decreased. Both the changes in soluble starch synthase (SSS) and granule-bound starch synthase (GBSS) activities showed a single-peak curve. The activity of SSS reached the peak on the 12th day after flowering,and then drastically decreased. However,the activity of GBSS peaked on the 15th day after flowering,while the amylose content of rice grain was almost at the highest this time. Moreover,the activities of SSS,GBSS and amylose content...更多 were significantly positively correlated at middle and late grain-filling stages.Nitrogen fertilizer application enhanced SSS and GBSS activities. Potassium fertilizer application played the same role at the early growth stage,on the contrary,it reduced the activities of the two enzymes at the late growth stage. Nitrogen fertilizer and potassium fertilizer application both promoted the starch accumulation,but too much nitrogen fertilizer had a negative effect on the starch accumulation. The optimum application rates of nitrogen and potassium fertilizers were 90 kg/hm2 (N) and 180 kg/hm2(K2O) for B You 827,respectively.

Key words: nitrogen, potassium, amylose content, soluble starch synthase, granule-bound starch synthase, relationship

摘要： 以优质杂交籼稻B优827为材料，通过施用不同水平的氮、钾肥，并在B优827灌浆时段测定籽粒的直链淀粉、总淀粉含量以及淀粉合成酶的活性,分析氮、钾对水稻灌浆过程中籽粒淀粉积累、淀粉合成关键酶活性的影响，以及直链淀粉的积累与淀粉合成关键酶活性间的相关性。B优827的直链淀粉含量在开花后20 d内呈线性增加，开花20 d后有所下降；可溶性淀粉合成酶活性变化呈单峰曲线，开花后12 d酶活性达到了最高值，以后随天数增加而迅速降低；淀粉粒结合型淀粉合成酶活性变化呈单峰曲线，开花后15 d酶活性达到最高值，开花后15 d籽粒直链淀粉含量也接近最高值；灌浆中后期可溶性淀粉合成酶（SSS)、淀粉粒结合型淀粉合成酶（GBSS)与直链淀粉含量呈现出显著的正相关关系。增施氮肥可以提高SSS和GBSS活性，施钾肥在生育前期提高SSS和GBSS活性，后期抑制两者的活性；氮肥和钾肥均有促进淀粉积累的作用，但氮肥施用量过高时会抑制淀粉的积累。适当控施氮肥、增施钾肥是提高B优827籽粒产量的有效途径。

关键词: 氮素, 钾素, 直链淀粉含量, 可溶性淀粉合成酶, 淀粉粒结合型淀粉合成酶, 相关性