Abstract: To determine the effects of elevated temperature during grain filling on grain quality of rice, Wuyujing 3 (japonica rice) was planted in pots under elevated night temperature(ENT) and elevated daytime temperature (EDT) at the grain filling stage by using farinfrared heaters. The two treatments both decreased brown rice rate, milled rice rate and head rice rate, while increased chalky rice rate and chalkiness. The effect of EDT was more significant. ENT decreased amylose content, whereas EDT increased it. Under ENT, starch granules were compact in arrangement with larger granule and clearer edge, by contrast, under EDT the starch granules were smaller and sphericshaped with few gaps. Xray diffraction patterns revealed larger relative crystallinity under both temperature treatments as compared to control with a less increase under ENT. The results show that compared with EDT, ENT exerted similar but less effects on milling quality, appearance quality and nutritional quality. However, effects of both treatments on starch structure, eating and cooking quality were different.

Key words: elevated night temperature, elevated daytime temperature, rice grain quality, starch structure

摘要： 以武育粳3号为材料，在开放环境下使用远红外加热器对水稻穗部进行增温处理，研究了灌浆结实期穗部日间或夜间增温对稻米品质的影响。结果表明，夜间增温降低了糙米率、精米率和整精米率，增加了垩白发生，降低了稻米的加工品质和外观品质，与日间增温影响一致。夜间增温提高了稻米蛋白质含量，与日间增温相似，但夜间增温有降低稻米直链淀粉含量的趋势，与日间增温相反。夜间增温处理淀粉结构与日间增温差异较分明，尤其是胚乳腹部，夜间增温胚乳腹部的淀粉粒个体较大，棱角分明，排列紧密；而日间增温淀粉体较小，呈圆形和椭圆形，但数量较多。夜间增温对淀粉相对结晶度的影响与日间增温相似，但夜间增温增幅较小。总体来说，灌浆结实期夜间增温对稻米的加工品质、外观品质、营养品质影响与日间增温一致，对蒸煮食味品质和淀粉结构的影响与日间增温存在很大的差异，且夜间增温对稻米品质的影响程度整体上小于日间增温。

关键词: 夜间增温, 日间增温, 稻米品质, 淀粉结构