两种叶型桢楠对干旱胁迫的生理响应OA

[Objective]Mechanisms underlying the adaptability and physiological response of Phoebe zhennan f.elliptical(large-leaf type)and P.zhennan f.oblong(small-leaf type)to drought stress were investigated,providing a theoretical basis for subsequent seedling cultivation and cultivation.[Method]Using 2-year-old seedlings of large-and small-leaf P.zhennan as materials,morpholog-ical indices and anatomical structures of leaves at different layers were measured.Then continuous drought treatment was applied to analyze growth indicators such as soil and leaf relative water content,aboveground dry mass,root dry mass,and root-to-shoot ratio,as well as photosynthetic parameters[net photosynthetic rate(Pn),stomatal limitation value(Ls),stomatal conductance(Gs),transpiration rate(Tr)and water use efficiency(WUE)],chlorophyll fluorescence parameters[maximum photochemical quantum efficiency(Fv/Fm),actual photochemical quantum efficiency(ΦPsⅡ),electron transport rate(ETR),photochemical quenching coefficient(qP)and non-photochemical quenching coefficient(NPQ)],and oxidative system indicators[catalase(CAT),malond-ialdehyde(MDA)and superoxide dismutase(SOD)].[Result]The leaves of large-leaf type were thicker and had more compact cellular structure compared to those of the small-leaf type.With prolonged drought stress,the relative water contents of soil and leav-es,as well as the aboveground dry mass of both types showed declining trends,while the root dry mass and root-to-shoot ratio in-creased significantly.Among the photosynthetic parameters,Pn decreased while Ls,Gs,Tr and WUE initially increased and then de-creased.For chlorophyll fluorescence parameters,Fv/Fm,ФPSⅡ,ETR,and qP initially remained stable and then declined,while NPQ firstly increased and then decreased.In the oxidative system,CAT activity and MDA content exhibited uprising trends,while SOD activity initially rose and then declined.When the soil relative water content was between 8.79％and 11.57％,the Pn and CAT level of large-leaf type were significantly higher than those of the small-leaf type.[Conclusion]Large-leaf type of P.zhennan exhibited higher drought resistance compared to the small-leaf type.