结实期水分胁迫对两系杂交稻产量及品质的影响

Effect of Water Stress During Grain Filling on theGrain Yield and Quality of Two-line Hybrid Rice

以6个两系杂交水稻为材料,研究结实期水分胁迫处理(-50kPa)对水稻产量及稻米品质的影响。结果表明:大多数品种的结实率、千粒重和产量处理都显著低于对照(浅水层)。剑叶的叶绿素含量和光合速率灌浆初期处理与对照无明显差异,但灌浆中后期明显比对照下降快,且籼型两系杂交稻比粳型两系杂交稻下降更快;根系活力在灌浆初期处理高于对照,灌浆中后期下降趋势与叶绿素和光合速率一致。干物质积累量处理低于对照,而茎鞘物质输出率和转换率都高于对照,成熟期茎、鞘中可用性糖的含量明显低于对照,说明水分胁迫处理加快了植株衰老,减少了抽穗后干物质积累,但促进了茎鞘储藏非结构性碳水化合物的输出。水分胁迫处理对稻米品质的影响表现为对出糙率、长宽比、糊化温度、直链淀粉和蛋白质含量无显著影响,精米率和整精米率表现因品种而异,垩白米率、垩白度和胶稠度均高于对照。

With six two-line rice hybrids as materials, the effect of water stress during grain filling on grain yield and quality was studied. The result showed that the percentage of ripened grains, 1000-grain weight and grain yield of most tested cultivars under water stress were significantly lower than those under well-watered treatments. The diffe- rences in chlorophyll content and photosynthetic rate were insignificant between water-stressed and well-watered flag leaves at early grain filling stage, but the reduction in chlorophyll and photosynthetic rate of the flag leaves for water-stressed plants than that for well-watered plants at the late grain filling stages, and indica hybrid combinations had faster reduction was larger than japonica hybrid combinations. Root activities of the water-stressed plants were higher than those of well-watered plants at the early grain filling stage, but they were decreased faster for the former than for the later at mid and late grain filling stages. The water-stressed plants had less accumulation of dry matter, higher export and transform percentage of the matter and lower content of usable sugars in stems and sheaths at maturity, suggesting that water stress enhanced senescence, reduced accumulation of dry matter after heading and facilitated remobilization of nonstructural carbohydrate (soluble sugars+starch) from the stems and sheaths. The effect of water stress on the grain quality were as follows: the differences in kernel length/width, brown rice, amylose content, protein content and alkali spreading value were insignificant between water-stressed and well-watered plants; milled rice and head milled rice varied with cultivars; chalkiness, percentage of chalky kernel and gel consistency of water-stressed plants were higher than those of well-watered plants.