开花和灌浆初期高温胁迫对国稻6号结实的生理影响

为研究杂交稻对开花结实期高温胁迫的生理生态适应性，选用具代表性的主栽杂交稻组合国稻6号、协优46，人工设计极值高温40~42℃，自始穗期至此后15 d每天6 h行热害处理，以自然气候条件为对照，比较研究高温胁迫对国稻6号与协优46结实的生理影响。结果表明，国稻6号具较高的受孕小穗成粒效应，即不仅不孕小穗率低，而且秕谷率也低。国稻6号对开花结实期高温较协优46钝感，两者在小穗育性和热害指数上的差异达到显著水平(P<0.05)。究其生理原因, (1)成熟期间稻株剑叶光能转化效率及光合效率较高，茎鞘储藏物质较丰；(2)成熟期间稻株仍具较强根系吸水能力与叶片蒸腾水平，维持蒸腾流利于光合物质运输；(3)成熟灌浆期稻株自动调节粒间顶端优势，增进迟开花的弱势粒充实成实粒。

Physiological Effects of High Temperature Stress on Grain-Setting for Guodao 6 during flowering and Filling stage

For a better understanding of high temperature stress on flowering and grain setting of rice during anthesis, a new rice hybrids Guodao 6 and a leading rice hybrid Xieyou 46 were selected to study the physiological and morphological adaptability to 40–42℃ of high temperature stress. The treatment was conducted with high temperature for 6 h each day from initial heading to following 15 days, and plants under natural condition was studied as control. Guodao 6 was less sensitive to high temperature stress, showing a stable yield and spikelet fertility and lower heat injury index in the stress condition. Physiologically analyzed data showed that in Guodao 6 during maturation, there were (1) higher flag leaf photosynthetic rate and higher transform rate from light energy to chemical energy, abundant carbohydrates stored in stem and leaf-sheath as well; (2) relatively stronger physiological activity of roots, and higher leaf transpiration rate, this enhanced translocation of photo-synthate to panicle; (3) better adjustment on “Apical grain superiority”, enhancing the filling of inferior spikelets.