Effects Of Drought Stress On Growth And Physiology Of Seven Willow Species

In this experiment,S.fragilis L.,S.integra Thumb.,S.linearistipularis(Fra.-nch.)Hao,S.viminalis,S.pammophila.,S.triandra L and S.Matsudana Koidz.were used as experimental materials.Under drought stress of different water gradients,the growth status and physiological indexes of willow were determined by pot weighing and water control method,so as to screen out drought-resistant willow species and provide theoretical basis for afforestation in arid areas.The main results showed:1.With the increasing degree of drought stress,the growth status,relative water content of leaves and fresh weight of willow decreased gradually.Under severe drought stress,the growth status of S.fragilis L.and S.triandra L.was very poor,and their leaves fell off.Other willow species were less influenced,plant height decreased,and their leaves fell off and curled to some txtent.2.With the increasing degree of drought stress,the Pn,Tr and Gs content of S.fragilis L.and S linearistipularis(Franch.)Hao showed rise first and then declined,Pn,Tr and Gs of other willow leaves were declined;Under the high depressed drought,the Ci of S.fragilis L.,S.Integra Thumb.and S.matsudana Koidz.were obviously higher than that of CK,the Ci of other willow had no obviously differences with CK.Under the drought depress,the relative chlorophyll content and PS II actual quantum of light production of all kind of willow leaves showed declined.3.With the increment of drought stress,the SP in S.fragilis L,S linearistipularis(Franch.)Hao,S.pammophila.and S.triandra L leaves showed rise first and then declined,the SP in S.viminalis,and S.matsudana Koidz.showed declined first and then rise;The Pro content of S.integra Thumb.increased,and S.linearistipularis(Franch.)Hao,S.pammophila.,S.trian-dra L and S.matsudana Koidz.showed increased first and then declined.4.With the increment of f drought stress,the MDA content of S.fragilis L.leaves increased,S.pammophila.leaves increased first and then declined.SOD activity in S.fragilis L.,S.pammophila.and,S.triandra L leaves showed declined first and then increased,which of the S.integra Thumb.,S linearistipularis(Franch.)Hao and S.viminalis were increased first and then declined.POD activity of S.fragilis L.,S.viminalis,S.linearistipularis(Franch.)Hao,S.pammophila.and S.triandra L were showed increased first and then declined,which of the S.matsudana Koidz.showed declined first and then increased.5.Fuzzy Membership Function Method was used to analyse and evaluate the drought resistance of several willow,the results showed:Under the high drought depress,the drought resistance sequence were:S.Pammophila.>S.Matsud-ana Koidz.>S linearistipularis(Franch.)Hao>S.viminalis>S.Integra Thumb.>S.triandra L>S.fragilis L.