The Phytotoxic Study Of Chlorpyrifos On Cucumber Under Sub-Optimum Condition

The use of pesticides generates large benefits in protecting crops from pests and in enhancing crop yields. However, the improper usage of pesticides can exert phytotoxicity on exposed crops. In china, since the thermophilic crops are mostly cultivated in unheated greenhouse during the cool season, the suboptimal condition with chilling temperature and low light is critical for agricultural productivity. Meantime, the usage of pesticides is carried on in these circumstances. Therefore, it is of great importance to study the phytotoxicity of pesticides under the condition of chilling temperature and low light. In this study, the phytotoxicity of chlorpyrifos on cucumber (Cucumis sativus), which is one of the major crops in greenhouse cultivation, as well as the stress response of cucumber, was investigated under different light intensity and temperature in the artificial climate incubators. The transcriptional changes of genes involved in various physiological processes such as photosynthesis, antioxidant, detoxification, defense and signal transduction, as well as the activities of several anti-oxidative enzymes were served as the endpoints. Moreover, in order to reveal whether the brassinosteroid can alleviate the phytotoxicity under suboptimal condition, the effect of pretreatment with24-epibrassinolide on the toxicity of chlorpyrifos was assessed under the condition of the chilling temperature and low light. The results showed that both the variations of light intensity and temperature could affect the phytotoxicity of chlorpyrifos on cucumber, and an appropriate reduction of the temperature and light intensity would be benefit for the adaption of cucumber after chlorpyrifos exposure. The impairments caused by chlorpyrifos were ameliorated by24-epibrassinolide pretreatment, demonstrating that the brassinosteroid could protect crops against the phytotoxicity of pesticides effectively and persistently. Our results preliminarily probed into the effects of environmental factors and plant hormone on the phytotoxicity of pesticides, and provided helpful information for the appropriate application of pesticides in greenhouse production.