Effects of NaCl and Na~+,Cl~- Stress on Photosynthetic Characteristics of Different Genotypes of Tomato Seedlings

The effects of NaCl(0,50,100,150 mmol/L)and Iso-Osmotic Na+ and Cl-(150 mmol/L)stress on the relative growth,the salt injury index,the content of chlorophyll and photosynthesis of four genotypes of tomato seedlings(L.pimpinellifolium,Liaoyuanduoli,Hongbaoshi,Liaoyuanhongmanao)were investigated.The results showed that the relative dry and fresh mass of shoot,relative plant height,relative leaf number,content of chlorophyll,net photosynthetic rate,stomatal conductance and transpiration rate of 4 tomato seedlings decreased gradually,the salt injury index increased gradually with increasing of salt concentrations.The tomato varieties of L.pimpinellifolium and Liaoyuanhongmanao held higher resistance to salt stress than the tomato varieties of Liaoyuanduoli and Hongbaoshi by comparing the correlative datum.Na+ ion hurt on different genotype tomatoes was more impotent then Cl-ion under Iso-Osmotic NaCl,Na+ and Cl-stress tomato seedling stage.The reduction of net photosynthetic rate under lower concentration NaCl(50 mmol/L)was the result of stomatal limitation,and non-stomatal limitation was the main reason for the decrease of photosynthetic rate under higher salinity in 4 genotype tomatoes.