高温胁迫对拔节期水稻光合作用和蒸腾速率的影响

为进一步了解高温对水稻生长的影响机制,为水稻的田间管理提供理论依据,以拔节期镇稻6号为试验材料,对其进行1d、3d和5d的昼间(10:00-15:00)高温(35～40℃)处理,之后转入28℃条件下恢复2d,以28℃未处理水稻为对照,研究较长时间高温处理及常温恢复对水稻光合作用及蒸腾速率的影响.结果表明:昼间高温处理,水稻叶片净光合速率(Pn)和胞间CO2浓度日变化呈先下降后上升的趋势,在中午13:00达到最低点,并且随处理时间的延长逐渐降低；气孔导度(Gs)和蒸腾速率(Tr)日变化呈先上升后下降趋势,在中午13:00达到最高点,并随处理时间的延长逐渐升高；短时高温处理(5 d)后常温恢复2d,上述指标即可恢复.结论:夏季高温对拔节期水稻光合作用造成影响,且主要是由非气孔限制因素引起的；蒸腾作用增强是降低叶温的生理机制.

Influence of High Temperature on Photosynthesis and Transpiration Rate of Rice Seedlings at Jointing Stage

The rice seedlings of Zhendao 6 at jointing stage were first treated under 35~40℃ from10:00 to 15:00 for 1 d,3 d and 5 d respectively and then the treated rice seedlings were recovered at 28℃ for 2 d to study influence of high temperature stress and normal temperature recovery on photosynthesis and transpiration rate of rice seedlings,to further understand the influence mechanism of high temperature to rice seedling growth and to provide the theoretical basis for rice field management.The results showed that the diurnal variation of net photosynthetic rate and intercellular CO2 of treated rice seedlings under high temperature presented the first descent and then rising trend,reached the lowest point at 13:00 and gradually reduced with prolongation of treatment time.The diurnal variation of stomatal conductance and transpiration rate of treated rice seedlings under high temperature was the first rising and then descent trend,reached the maximum point at 13:00 and gradually increased with prolongation of treatment time.Conclusions: the photosynthesis of rice seedlings at jointing stage is mainly affected by non-stoma limiting factors under high temperature and transpiration reinforcement is the physiological mechanism to lower leaf temperature.