Effects Of Exogenous Chemicals On Chilling-Resistance Of Tomato Seedlings

“First501” was selected as material. Through spraying different concentrations AsA, SA, ABA as exogenous chemicals, tomato seedlings were induced and treated by low temperature. Through these studies, the relative conductivity, the content of MDA, AsA and praline, and other indicators in leaves of tomato. The results were concluded as follows:（1） Compared to CK, we found those tomato which were sprayed AsA（10mmol/L、50mmol/L、100mmol/L）showed better. Under the threaten of low temperature, the sprayed treatment reduced damage of tomato seedling and the all membrane permeability, restrained the MDA production and O-.2production rate, increased the content of free radical scavengers（AsA and GSH）, praline, and improved the low temperature stress resistance ability. This showed that exogenous AsA can improve, to some extent, the cold resistance of tomato seedlings. Different concentration of exogenous AsA can relieve the low temperature injury to tomato seedlings, and the optimum concentration of AsA was10mmol.L-1, with the elevate of concentration of exogenous AsA, will reduce the effect on resistance of tomato seedlings in chilling injury.（2） The tomato which were sprayed SA（150mmol/L、300mmol/L、450mmol/L）sh owed better. Under the threaten of low temperature, the sprayed treatment increased seedling strength index of tomato seedlings, reduced the the content of MDA and H₂O₂production,the relative conductivity and O-.2production rate, increased the content of free radical scavengers, praline, so reduced Chilling injury index of tomato seedlings,and improved the low temperature stress resistance ability. This showed that exogenous SA can improve, to some extent, the cold resistance of tomato seedlings. Spraying different concentration of exogenous SA can relieve the low temperature injury to tomato seedlings, and the optimum concentration of SA was300mmol/L.（3） Those tomato were sprayed AsA（10mmol/L、50mmol/L、100mmol/L）sh owed better. Under the threaten of low temperature, the sprayed treatment reduced damage of the leaves of tomato seedling, restrained the MDA production and O2-.production rate, reduced the content of H₂O₂, increased the content of free radical scavengers, praline, and improved the low temperature stress resistance ability. This showed that exogenous ABA can improve, to some extent, the cold resistance of tomato seedlings. After sprayed ABA, the low concentration of ABA can increase the tomato seedlings to resistance to chilling injury, but the high concentration of ABA（250mmol/L） can reduce the tomato seedlings to resistance to chilling injury, the result showed the optimum concentration of ABA was200mmol/L.