Effect Of Drought Stress And Rewatering On The Growth And Photosynthetic Physiological Characteristics Of Salix Matsudana Leaves And Twigs

Corticular photosynthesis is an assimilative process of CO2 which comes from inner respiration and diffusion of transpiration stream in chlorenchyma,including cortex,xylem ray,pith and so forth.Drought will limit photosynthesis and cause defoliation,yet as an effective way of carbon recycling,corticular photosynthesis provide photosynthate and play an integral part in enhancing plants competition for survival.After rewatering,the organs development and morphogenesis of plants relies on corticular photosynthesis.At present,only a few researches have been carried to study the contribution of corticular photosynthesis in plants growth after rewatering.In order to detect the contribution of corticular photosynthesis in plants growth,we took Salix matsudana as test material and cultured in pot to control the water content.We studied the dynamic change of growth and photosynthetic physiology of Salix matsuda after rewatering,and the results were as follows:(1)The relative growth of diameter,relative variation of leaf number and root biomass are recovered to the control level under rewatering after slight drought and moderate drought.Yet the relative variation of leaf number surpassed the control,revealed super compensate effect and the root biomass was not able to recovered to the control level under rewatering after severe drought.(2)After rewatering,the relative water content and gas exchange parameters were recovered to the control level.The actual photochemical efficiency and electron transport rate had no obvious disparity with the control level in the process of drought and rewatering.The chlorophyll and carotenoid content recovered to the control level after rewatering.(3)There existed positive correlation between the descend range of relative water content and drought degree in twigs.The relative water content of twigs revealed super compensate effect under rewatering after moderate drought and severe drought;the net photosynthetic rate and respiration rate recovered to the control level after rewatering;and the actual photochemical efficiency and electron transport rate showed no disparity with control level,yet decreased under rewatering after severe drought.We have studied on the dynamic changes of growth indexs and photosynthetic physiology of Salix matsudana after rewatering,and detected the relations among the growth,leaves photosynthesis and corticular photosynthesis,and thus to reveal the contribution of corticular photosynthesis in growth of Salix matsudana.