Defferential Responses And Adaptations Of Dioecious Populus Cathayana To Foliar Application Of Pesticide

Dioecious plants show sexual differences to abiotic stresses.However,the effects of exogenous pesticide application on female and male plant growth and their associated adaptation mechanisms are unclear.Therefore,this study aimed to assess the impact ofλ-cyhalothrin(λ-CY),a broad-spectrum pesticide,on shoot and root in the dioecious Populus cathayana,we investigated The effects ofλ-CY on leaf physiology and phyllosphere bacterial community,explored the impact of pesticide on root exudates of male and female Populus cathayana,and finally how to affect the growth of male and female Populus cathayana by changing the rhizosphere bacterial community and physicochemical soil properties.The main results are as follows:(1)Different responses and adaptations of dioecious P.cathayana shoot to foliar application ofλ-CYPhysiological leaf traits such as photosynthetic apparatus(net photosynthetic rate(P_n),stomatal conductance(g_s)and transpiration(E))of males were significantly higher than those of females,independent of pesticide use.In contrast,pesticide application significantly reduced the photosynthetic apparatus for both sexes,and the reduction was greater in males than females.Also,pesticide application significantly increased peroxidase activity and malondialdehyde(MDA)content and maintained superoxide dismutase(SOD)activity and total chlorophyll content in leaves of males.Moreover,plant sex had a greater effect on phyllosphere bacterial community composition and community assembly than pesticide application.However,pesticide application affected the relative abundance of specific bacterial taxa where Proteobacteria was negatively affected and Actinobacteria was positively affected at the phylum level.(2)Different responses and adaptations of dioecious P.cathayana root to foliar application ofλ-CYThe sequential application ofλ-CY significantly suppressed male shoot-and root biomass,with little effect on the growth of females.Females possessed a higher intrinsic chemo-diversity within their root exudates,and their levels of various metabolites(sugars,fatty acids,and small organic acids)increased after exposure toλ-CY with consequences on bacterial community composition.Maintaining high bacterial alpha diversity and recruiting specific bacterial groups slowed down the loss of rhizosphere nutrients in females.In contrast,the reduction in bacterial alpha diversity and network structure stability in males was associated with lower rhizosphere nutrient availability.In addition,the significant decrease in soil bacteriaαdiversity and soil nutrient availability in the rhizosphere of males may be the reason for the more substantial inhibition.In conclusion,after the application of pesticide,there are sex-specific responses in the shoot-and root parts of both male and female poplar.The male is more affected by the application of pesticide than the female,and the growth is more significantly inhibited.Our study provides important insights into the sex-specific responses of Populus cathayana to pesticide application and highlights the importance of considering plant physiology and microbial community composition when making decisions about pesticide use in poplar plantations.