以培杂泰丰、粤晶丝苗和天优998为材料,分别设置不施氮、中氮和高氮3个不同的氮肥水平(即施纯氮0、120和180 kg/hm²,依次记为NN、MN、HN),研究始穗期遮荫(分别为双层遮荫、单层遮荫和不遮荫,依次记为DS、SS、CK)对不同基因型水稻产量及一些生理特性的影响。结果表明,与不施氮处理相比,遮荫处理结束后恢复5d高氮显著增加水稻叶面积指数、茎鞘干质量、总干质量、茎鞘物质输出量和茎鞘物质转运率,水稻剑叶的光合速率和气孔导度也显著提高。高氮处理下水稻的收获产量、有效穗数和每穗总粒数显著高于不施氮处理,而结实率和千粒重却显著降低。与不遮荫相比,双层遮荫处理水稻叶面积指数、茎鞘干质量、总干质量、剑叶的光合速率和气孔导度显著降低,双层遮荫处理水稻的收获产量和有效穗数也显著降低。氮肥和遮荫的互作效应对水稻叶面积指数、茎鞘干质量、总干质量、有效穗数以及收获产量的影响也达到显著水平。在单层遮荫条件下,增施氮肥可以减轻遮荫对水稻叶面积指数、叶片干质量、茎鞘干质量、总干质量、有效穗数和收获产量的不利影响。对不同品种而言,超级杂交稻天优998受到氮肥和遮荫的影响更大。

Effects of shading at the beginning of heading stage on grain yields and some physiological characteristics under different nitrogen application rates in different rice genotypes were investigated by using Peizataifeng, Yuejingsimiao and Tianyou 998 as test materials. Nitrogen application rate was 0, 120 and 180 kg/hm², which was expressed as NN, MN and HN in order, respectively. The shading treatment was double-deck shade, single-deck shade and no shade, which was expressed as DS, SS and CK, respectively. Compared with NN, leaf area index (LAI), stem dry weight, total dry material weight, dry weight output and export percentage of dry matter in stem and sheath under HN were higher in five days recovery under shade treatment in rice. And photosynthesis rate (P_r) and stomatal conductance (G_s)in the first leaf from the top under HN was higher than that under NN, respectively. Furthermore, grain yield and effective panicle number per hill and total number of spikelets per panicle were significantly higher under HN, whereas seed setting rate and 1000-grain-weight was remarkably fewer than that under NN. Compared with no shade treatment, stem dry weight, total dry material weight, LAI, P_r and G_s declined evidently under DS. And grain yield and effective panicle number per hill decreased significantly, too. There were significant effects of interaction between nitrogen application and shading on LAI, stem dry weight, total dry weight, effective panicle number per hill and yield. Nitrogen application under single-deck shade treatment could reduce harmful effects on LAI, stem dry weight, total dry weight, effective panicle number per hill and grain yield in rice. Among the tested cultivars, super hybrid rice Tianyou 998 was the most sensitive to nitrogen application and shading.