Effects Of Light And Saline Irrigation On The Physiological Functions In Leaves Of Actinidia Arguta

To study the suitability of Actinidia arguta in Xinjiang,we investigated its physiological response to light and soil salinity characteristics in Xinjiang.In this study,we used the early-ripening Actinidia arguta variety"Kui Lv"from Dalian as the test material and conducted pot experiments based on the light and soil salinity characteristics of the introduced sites.Long-term light stress（time periods:30,60,90 d;shade levels:0%,48%,65%,80%）;short-term light stress(light intensity:0,800,1000,1600±50μmol·m^-2·s^-1;time:11:00-16:00);and saline irrigation（complex salt concentration:0,20,40,60,80,100 mmol/L）were investigated.The physiological responses of Actinidia arguta under saline irrigation（complex salt concentrations:0,20,40,60,80,100 mmol/L）were analyzed by SPSS.The differences in leaves physiological functions of Actinidia arguta under light and saline irrigation were also analyzed by SPSS.The main findings were as follows:（1）Shade reduced photosynthesis in Actinidia arguta but had little effect on photosynthetic pigments.The net photosynthetic rate（Pn）of Actinidia arguta decreased under shade treatment.In contrast,stomatal conductance（Gs）of Actinidia arguta decreased.Still,chlorophyll content increased,indicating that the decrease in net photosynthetic rate（Pn）of Actinidia arguta was not due to chlorophyll and stomatal factors.（2）Shade reduced the antioxidant enzyme activity,malondialdehyde content and abscisic acid content and increased the soluble protein content of Actinidia arguta.The activities of superoxide dismutase and catalase in leaves of Actinidia arguta were the lowest under 65%shading treatment for 60 d,with a 48%and 41%decrease compared to the control.The content of malondialdehyde in leaves of Actinidia arguta has no significant change in each time period of 65%shading treatment.The soluble protein and abscisic acid contents in leaves of Actinidia arguta showed maximum and minimum values at 65%shade treatment,with significant changes from 30 to 60 d and no significant differences from 60 to 90 d.（3）The effect of different light intensities on Actinidia arguta in short periods of time was small,and none of the physiological indicators changed significantly.Short-term acute light exposure resulted in a significant increase in peroxidase activity and abscisic acid content;suggesting that enhanced peroxidase activity and abscisic acid content under short-term acute light exposure is an important mechanism for Actinidia arguta to adapt to short-term acute light exposure.（4）Salt stress treatment changed various physiological indicators in leaves of Actinidia arguta.The changes were not significant after 7 d of saline irrigation treatment;after 14 d,chlorophyll b content,superoxide dismutase and catalase activities,as well as a soluble protein and malondialdehyde content in leaves of Actinidia arguta showed significant increases at complex salt concentrations up to 60 mmol/L,respectively:10%,17%,35%,33%,33%.This indicates that the physiological activities are all affected to varying degrees at complex salt concentrations up to 60 mmol/L and will be detrimental to their growth.This preliminary study investigated the light adaptation and salt tolerance of Actinidia arguta seedlings.The optimum light conditions for Actinidia arguta cultivation in Xinjiang were 65%shade for about 60 d and a saline soil environment with salinity less than 60 mmol/L.The study results provide a reference for how to introduce Actinidia arguta in Xinjiang successfully.