干热胁迫对杨树叶片气体交换和叶绿素荧光参数的影响

Effects of drought and heat stress on gas exchange and chlorophyll fluorescence parameters of poplar leaves

为了探讨干热胁迫对不同品种杨树叶片气体交换和叶绿素荧光参数的影响,以吴屯杨、小青杨和小美旱杨一年生嫩枝为材料,利用人工气候箱和PEG浓度控制生长温度、干旱条件,处理24 h后测定气体交换和叶绿素荧光参数以及光合色素的含量。结果表明:1)随着胁迫程度的增加,3种杨树叶片的净光合速率(Pn)和气孔导度(Gs)随着干热胁迫的程度增加均呈先上升后下降的趋势,胞间CO2浓度(Ci)则整体呈下降趋势,吴屯杨和小美旱杨的蒸腾速率(Tr)呈先上升后下降的趋势,而小青杨叶片的蒸腾速率持续增加,在重度干热胁迫时达到最大值;2)3种杨树在重度干热胁迫条件下光系统Ⅱ反应中心及其电子传递链的结构均受到了不同程度的损伤;3)3个杨树品种的类胡萝卜素含量随干热胁迫程度的增加呈稳定上升的趋势,总叶绿素与叶绿素a、b含量总体呈下降趋势。4)综合各项生理指标结果分析,3种杨树中,小青杨和吴屯杨的耐干热能力较强,小美旱杨最弱。

In order to investigate the effects of drought and heat stress on gas exchange and chlorophyll fluorescence parameters of different varieties of poplar leaves,the annual twigs of Wutun poplar,populus pseudo-simonii and populus popular’s were taken as materials,and the artificial climate box and PEG concentration to control growth temperature and drought conditions were adopted,after the materials were treated for24hours,the gas exchange and chlorophyll fluorescence parameters as well as the content of photosynthetic pigments were measured.The results show that1)As the degree of intimidation increases,Pn and Gs of the three varieties of poplar leaves all showed a tendency of first increasing and then decreasing;and the intercellular CO2concentration(Ci)showed an increasing tendency;and Tr of Wutun poplar and populus popular’s showed a tendency of first increasing and then decreasing,while that of populus pseudo-simonii continually increased and reached the maximum value in the conditions of heavy drought and heat stress.2)The determination results of chlorophyll fluorescence parameters showed that the structures of photosystemⅡreaction center and its electron transport chain of the three varieties of poplar were all damaged in different degrees in the conditions of heavy drought and heat stress.3)The contents of carotenoids in the three poplar varieties showed a tendency of constant increasing with the increase of drought and heat stress,while the contents of total chlorophyll and chlorophyll a and chlorophyll b decreased.4)Based on the analysis of the results of various physiological indicators,among the three poplar varieties,populus pseudo-simonii and Wutun poplar had strong resistance to drought and heat,while populus popular’s had the weakest resistance.