Research On Effect Of Induced Resistance In Tomato Against Gray Mold By Exogenous Chemicals

In recent years, tomato gray mold (Botrytis cinerea)was one of the main diseases of tomato cultivated in protected areas, all kinds of Greenhouse have occurred, particularly prevalent in the north protected. The disease can not only harm the stems, leaves, flowers and fruits, and a long duration, the incidence of early, but also do the beans, leeks, onions, eggplant, peppers and other crops, has now been the implementation restrictive barriers of the cultivated tomato production. In this paper, different concentrations of tomato plants were studied by salicylic acid, chitosan, and spermidine3kinds of exogenous substances. Determine the optimal induction interval and duration, the optimal concentration of inducer selected according to the relative induction. Using the optimal concentration of inducer research the physiological mechanisms of tomato resistance to Botrytis cinerea in the best period. Designed to help local solute Botrytis cinerea controlling problem and foundation for further studying the mechanism of induced resistance in other crops and in the production practice application.First, exogenous induced resistance material on the tomato resistance to Botrytis cinerea induction were studied. Using three kinds of chemical substances on Botrytis cinerea mycelial growth diameter and conidial germination, and germination of tomato seeds and tomato seedling height, stem diameter, the impact of measured results show that the tested chemicals tested the concentration range of spore germination and mycelial growth were no significant inhibition. Germination of tomato seeds have little effect, and only salicylic acid role in promoting the germination of tomato seeds, plant height and stem diameter of tomato seedlings are homogeneous almost. The results not only indicate that these chemicals are safe to use in a certain concentration range, does not affect the growth indicators of the tomato, also confirmed the role of prevention does not come from the bactericidal effect. The relative induction after the treatment has improved to varying degrees, including the best control effect of salicylic acid,at the same time, the induced effect had significant differences in tomato resistance to Botrytis cinerea at different induction time, growth of4leaves>2leaf stage>8leaf stage. The induced effect was great different between inducing by different concentrations of agents and different use,of the best relative controlling effect of150mg/L salicylic acid,200mg/L chitosan,150mg/L spermidine, were67.66%,33.23%,29.38%. The best induced effect on Botrytis cinerea generated in the interval of three days after challenging vaccination,using150mg/L concentration of salicylic acid in tomato plants. And resistance to the duration was10～15d. At the same time study activity changes in a number of defense of tomato plants and the relationship with the resistance performance in the process of induction of resistance. Studies have shown that changes in catalase, peroxidase, polyphenol oxidase, phenylalanine ammonia lyase showed a trend of increased and then decreased in tomato gray mold induced systemic resistance, and significantly higher than the control treatment. The law in changing show that positive correlation between these four enzyme activities and induced resistance on Botrytis cinerea. After salicylic acid treatment, the increasing on content of malondialdehyde is closely related to the improvement of disease resistance.In addition, with the extension of the initial induction time, the activity of these defense from the first day after treatment began to increase in the third day to the fourth day peak, then gradually decreased. The increase of these enzyme activities inhibit the synthesis of pathogenic substances, so the pathogen infection and expanded by the effective limit at the same time the expression of host resistance as the enzyme activity increase was further stimulated.