干旱胁迫对夏玉米叶片光合及叶绿素荧光的影响

Effects of Drought Stress on Photosynthesis and Chlorophyll Fluorescence of the Summer Maize Leaf

选用华北地区大面积种植的夏玉米品种郑单958、承玉2号、鲁单981作为试验材料,通过研究干旱胁迫条件下的玉米叶片光合、叶绿素荧光等指标随着土壤水分的动态变化规律,以期为夏玉米干旱的生理生态变化监测及水分高效利用提供理论依据。研究发现,在土壤含水量70%左右时,随着土壤相对湿度的下降,上述3个夏玉米品种仍能保持其叶片水分状态。郑单958、承玉2号、鲁单981的叶片净光合速率在土壤水分中等条件下最大,分别为39.9、38.8、38.4μmol CO2/m2.s;在土壤相对湿度较低时,郑单958、承玉2号、鲁单981的叶片净光合速率下降趋势明显(P<0.05)。叶片水势变化规律为:在土壤相对湿度>90%时,对水分胁迫郑单958、承玉2号不敏感,鲁单981敏感;在土壤相对湿度<70%时,水分胁迫条件下承玉2号不敏感,而鲁单981、郑单958敏感。气孔导度(gs)变化规律:随着水分胁迫加剧,3个夏玉米品种气孔导度均下降,在土壤水分较高时,气孔导度变化规律不明显,在土壤水分较低时,气孔导度明显下降(P<0.01),细胞间隙CO2浓度(Ci)随土壤水分胁迫加剧而上升。上述结果表明:与叶片的光合和水分状况相比,夏玉米的气孔对土壤水分的匮缺更为敏感。

Choose the summer maize varieties ： Zhengdan958, Chengyu2 and Ludan981, which are planted widely in North China as experimental material. In order to understand the changes of plant physiology and ecology under the different soil drought stress, the effects of soil drought stress on photosynthetic character and chlorophyll fluorescence of the maize leaf were studied. When the soil water content is about 70% , the above varieties can keep the leaf moisture with the soil water content decreasing. The net photosynthetic velocities of Zhengdan958, Chengyu2 and Ludan981 are 39.9, 38.8 and 38.4 μmol CO2/m^2·s respectively. When the soil relative water content is low, the net photosynthetic velocities of the three varieties descend obviously （P 〈 0.05 ）. When the soil water content 〉 90% , Zhengdan958 and Chengyu2 are less sensitive to water stress than Ludan981 ; when 〈 70% , Zhengdan958 and Ludan981 are more sensitive than Chengyu2. The stomatal conductance of the three varieties all descend with water stress strengthening. The stomatal conductance descent are more obvious in low soil water content than in high soil water content （P 〈 0.01 ）. While intercellular CO2 concentration （ Ci） increased with water stress strengthening. Above results indicated that summer maize stomatal is more sensitive to soil water content than photosynthesis.