梯度干旱胁迫对水稻叶片光合和水分状况的影响

Effects of Drought Stress on Photosynthesis and Water Status of Rice Leaves

采用温室营养液培养方式,通过添加0%、10%、20%、30%PEG6000模拟干旱胁迫,对水稻幼苗叶片的光合作用和水分状况进行比较分析。结果表明:1)在干旱胁迫下,水稻叶片的光合速率、气孔导度、叶肉导度、总导度和叶绿体内CO2浓度等都显著降低;2)在干旱胁迫条件下,限制光合作用的非气孔限制值并没有显著提高,而气孔限制值则大幅提高;与正常水分条件相比,扬稻6号和汕优63在30%PEG干旱胁迫下气孔限制值分别提高了42%和81%;3)光合速率与气孔导度、叶肉导度、总导度及叶绿体内CO2浓度呈正相关;4)在重度干旱胁迫下(20%和30%),叶片水势和含水量都显著下降,并且叶片水势与气孔导度、叶肉导度和总导度呈正相关。因此,气孔关闭导致的叶绿体内CO2浓度降低是限制光合作用的最主要因素,同时叶片水势的降低增加了叶片内CO2传输的阻力。

Hydroponic experiments were conducted to compare photosynthesis and water status in rice leaves under normal conditions and drought stress simulated by addition of 10%, 20% and 30% polyethylene glycol （PEG6000）. The results were listed as follows： 1） under drought stress, leaf photosynthesis, stomatal conductance, mesophyll conductance, total conductance, and chloroplastic CO2 concentration were decreased; 2）there was no significant difference in non-stomatal limitation under drought stress and normal conditions. But compared with normal conditions, stomatal limitation under 30 % PEG simulated drought stress in Yangdao 6 and Shanyou 63 were increased by 42% and 81%, respectively; 3） there were positive relationships between photosynthesis and stomatal conductance, mesophyll conductance, total conductance and chloroplastic CO2 concentration; 4） under severe drought stress （20 % and 30 %）, leaf water potential and water content were decreased significantly. And leaf water potential was positively correlated with stomatal conductance, mesophyll conductance and total conductance. Therefore, reduced chloroplastic CO2 concentration resulted from stomatal closure was the major limitation of photosynthesis. And the decreased leaf water potential may increase the internal CO2 transport resistance.