Effect of Salt Stress on Photosynthetic Characteristic and the Content of Chlorophyll and β-carotene in Tomato Seedling Leaves

Taking two different local tomato cultivars,‘Shihong 305'and‘Black tomato'as materials,under different salt stress level with substrate culture,the effect of 50,100,150,200 mmol/L different salt stress on photosynthetic characteristic and the content of chlorophyll a,chlorophyll b,total chlorophyll andβ-carotene in tomato seedling leaves were studied,in order to explore the salt stress on the influence of photosynthetic characteristic and content of photosynthetic pigment.The results showed that,the general tends of Pn,Tr,Gs and Ci in the two cultivars' s leaves were all first increased then decreased together with the rise of salt content in different treatment,and the main cause of Pn decreasement was stomatal limitation.But the WUE was higher in heavy salt stress treatment,this most related to the descent of Pn and Tr.The content of chlorophyll a was decreased along with the change of salt content,but the change of chlorophyll b,total chlorophyll andβ-carotene were same to Pn.This illustrated that salt stress could affect the photosynthesis and chlorophyll synthesis in plant leaves and also had influence on the content of secondary pigments,further more,the change of β-carotene content was correlated to chlorophyll content and Pn in tomato seedling leaves.