Effect of NaCl 、Na~+-salt and Cl~- —salt Stresses on Photosynthetic Characteristics and Sucrose Metabolism in Tomato Leaf

Using the cultivated tomato cultivar Liaoyuanduoli as material,the effects of NaCl,Cl——salt and Na+-salt iso-osmotic stresses on tomato leaf photosynthesis and sugar metabolism were comparatively studied.The results showed that NaCl,Cl——salt and Na+-salt iso-osmotic stresses reduced tomato leaf net photosynthetic rate and respectively decreased 15.18%,6.23% and 10.11% compared with the control after 7 d of stress;all the three stress treatments reduced tomato leaf stomatal conductance,intercellular CO2 concentration and transpiration rate,and reduced the content of chlorophyll a and b in tomato leaves.In the above changes in photosynthetic parameters,the efficiency of Na+-salt treatment was greater than that of the Cl——salt treatment.NaCl,Cl——salt and Na+-salt iso-osmotic stresses significantly increased fructose and glucose le-vels in tomato leaves compared with the control;the increase rate of Na+-salt stress was greater than that of the Cl——salt stress.Iso-osmotic of the three stress treatments decreased sucrose and starch content in tomato leaves compared with control.NaCl,Cl——salt and Na+-salt iso-osmotic stresses increased invertase activity in tomato leaves,of which NaCl treatment increased most remarkably,followed by Na+-salt treatment.Also,the results showed that NaCl,Cl——salt and Na+-salt iso-osmotic stresses damaged the tomato leaf photosynthetic function,reduced the efficiency of photosynthesis,and the effect of Na+ was greater than that of Cl-.NaCl,Cl——salt and Na+-salt iso-osmotic stresses altered the direction of sugar metabolism in tomato leaves,significantly increased the decomposition rate of starch and sucrose,increased fructose and glucose content in tomato leaves,and the effect of Na+ on sugar metabolism was significantly greater than that of Cl-in tomato leaves.