Mechanisms Underlying Foliar Water Uptake Of Five Typical Plant Species In The Mu Us Desert

Dew plays an important role in water supplying in desert ecosystems.Previous studies have shown that a large number of desert plants can absorb and use dew through foliage.However,it is unclear whether several typical plants in the Mu Us Desert can absorb water through their leaves.In this study,we examined Agriophyllum squarrosum,Corispermum puberulum,Leymus secalinus,Chenopodium aristatum,and Sophora alopecuroides,to explore the ability of five plant species'leaf water absorption and their physiological responses in the Mu Us Desert,using dew covered experiments,stable isotope tracer technology,and fluorescent tracer technology.The main results are as follows:(1)All the five plant species had the ability to absorb dew through foliage.After deuterium labelled,the range of?~2H of A.squarrosum,C.puberulum,L.secalinus,and C.aristatum changed from-28?-14‰to 16?99‰,but their absorption amounts were different.A.squarrosum,C.puberulum,L.secalinus,and C.aristatum had stronger absorption capacity than S.alopecuroides.L.secalinus had the ability to move water absorbed by foliage downwards.After the treatment,the?~2H of its root water and rhizospheric soil increased by 16.03‰and 17.74‰,indicating that L.secalinus can transport absorbed water to the roots and the rhizospheric soil via stem.However,the?~2H of other four plant species'did not significantly change,suggesting that they did not have the same ability,and the absorbed water may be maintained in leaf or returns to the atmosphere through transpiration.(2)The structures of water absorption and storage in the leaves of the five plants were different.The fluorescence tracer experiment results showed that A.squarrosum had two water entrance channels(leaf epidermis and trichomes),while C.puberulum,L.secalinus,C.aristatum,and S.alopecuroides absorbed dew merely through the leaf epidermis.After the dew entering into the leaf epidermis,the five plants had different water storage capacities.A.squarrosum,C.puberulum,and L.secalinus had more water-storing tissues to save water,and all their vascular tissue,spongy tissue,and mechanical tissue can store the absorbed water.The water storage capacity of C.aristatum and S.alopecuroides were relatively weak,and they only used vascular tissue to save the water.(3)The five plant species had different physiological response towards foliar water uptake.A.squarrosum,C.puberulum,L.secalinus,and C.aristatum could improve their water physiological state through water absorption,while S.alopecuroides did not significantly respond to foliar water uptake.After water absorption,the leaf water potential of A.squarrosum and C.aristatum increased by 24%and22%;the leaf water content of A.squarrosum,C.puberulum,and L.secalinus increased by 2.94%,2.45%and 4.05%,respectively;the stomatal conductance of A.squarrosum decreased by 57%,and L.secalinus increased by 50%;and all the leaf water potential,leaf water content,as well as stomatal conductance of S.alopecuroides did not significantly change.(4)The results show that leaf water absorption of A.squarrosum,C.puberulum,L.secalinus,and C.aristatum maybe plays an important role in their survival in the desert,but it has few effect on S.alopecuroides.