Gender Differences In Response Of Populus Euphratica To Extreme Drought

This paper takes female and male Populus euphratica in the lower reaches of the Tarim River as the research object,and combines field observation experiment with indoor experiment analysis to study the gender differences of drought resistance of female and male Populus euphratica in the lower reaches of the Tarim River,with the aim of explaining the difference of drought resistance of Populus euphratica from a gender perspective.The results provide a reference for the conservation and restoration of Populus euphratica in the study area.Based on the multi-year ecological water conveyance in the lower reaches of Tarim River,female and male Populus euphratica from the three sections of Yingsu,Arakan,Yiganbujima were selected as the research objects.The leaf anatomical structure,leaf stomatal characteristics,light response curve and maximum light intensity of female and male Populus euphratica at different distances from the river were discussed by means of dynamic monitoring of field plots and laboratory experimental analysis.Drought resistance of chemical efficiency,antioxidant household protease system and osmotic regulators,leaf water potential,stem flow and other physiological and ecological indicators are different.The main results are as follows:(1)The stomatal density of Populus euphratica leaves in the lower reaches of the Tarim River is larger than that of the upper epidermis;the stomatal length of the upper epidermis is larger than that of the lower epidermis;the stomatal density increases with the increase of drought stress,while the stomatal length decreases,indicating that male Populus euphratica has stronger drought tolerance than female Populus euphratica.Under light drought stress,the leaf anatomical structure index level of female Populus euphratica was significantly better than that of female Populus euphratica.With the increase of drought stress,the leaf anatomical structure index level of male Populus euphratica was significantly better than that of female Populus euphratica.It indicated that with the increase of drought stress,male Populus euphratica had stronger drought resistance than female Populus euphratica.(2)The photosynthetic electron transfer rate(ETR)of female Populus euphratica was significantly lower than that of male Populus euphratica at 50 meters and 500 meters away from the river,indicating that under the same drought stress,female Populus euphratica had weak photosynthesis,less available water and less adaptability to drought stress than male Populus euphratica.(3)The drought resistance of female Populus euphratica was better than that of male Populus euphratica under two drought stress gradients.In terms of proline accumulation,female Populus euphratica has stronger drought resistance than male Populus euphratica.With drought stress intensifying,the soluble sugar content of male Populus euphratica decreased,while that of female Populus euphratica increased.In conclusion,female Populus euphratica has stronger drought resistance than male Populus euphratica under severe drought stress.(4)Under more drought conditions,female Populus euphratica could maintain higher leaf RWC,and the decline rate of female Populus euphratica leaf RWC was significantly lower in the process of increasing drought stress.Therefore,female Populus euphratica has stronger drought resistance than male Populus euphratica in terms of relative water content of leaves.No matter what degree of drought stress or the increase of drought stress,the change of leaf water potential of Populus euphratica basically conforms to the rule that the water potential of female Populus euphratica before dawn is lower than that of male Populus euphratica,which indicates that female Populus euphratica suffers more severe drought stress,and male Populus euphratica has stronger drought tolerance than the females.(5)According to different indicators,it is preliminarily concluded that under the drought stress habitat in the lower reaches of the Tarim River,male and female Populus euphratica adopt different coping strategies to resist drought stress.The results showed that the drought resistance of male and female Populus euphratica was different: stomatal characteristics of leaves,anatomical structure characteristics of leaves,light and electron transfer rate and water potential of pre-dawn leaves showed that male Populus euphratica had stronger drought resistance than female;while the changes of antioxidant enzyme activity,proline content,soluble sugar content and relative water content of leaves showed that male Populus euphratica had stronger drought resistance than female Populus euphratica.Populus euphratica has stronger drought tolerance.