Effects Of The Treatment Of DPC On Cotton Defensive Action And The Feeding And Metabolism Of Aphis Gossypii

Cotton is the main cash crop in Xinjiang,occupying an important strategic position in its economy,However.In recent years,due to the change of cotton farming methods,irrational use of pesticides and other factors,resulting in cotton aphids rose to the main insect pests,seriously affecting the quality of cotton.DPC as a plant growth retarder is widely used in the production practice and which is used to regulate cotton growth and enhance cotton resistance under the condition of the reasonable utilization.Due to the cotton cultivation and irrational use of pesticides and other factors to the increase of the main pests of Aphis gossypii in cotton fields.However,there are few researches on the effect of DPC for defense mechanism of cotton and the metabolism of Aphis gossypii.Therefore,"Xinluzao 55" were used as the test material to analyze the relationship among DPC,cotton and Aphis gossypii to provide theoretical basis for regulating the growth of cotton and controlling Aphis gossypii.The main findings are as follows:1.The effects of DPC on photosynthetic rate,SPAD value,wax content and thickness of cotton leaves were studied.The results showed that spraying DPC improved the photosynthetic rate of cotton leaves and which was the concentration of 4.5g/hm2 and 7.5g/hm2 could gradually increase the photosynthetic rate of cotton leaves,the concentration of 15g/hm2 could promote the photosynthesis of leaves for short time and maintain the photosynthetic rate stable.The SPAD value measured in the continuous 12 days showed that the SPAD value increased with time and was positively correlated with the concentration.The concentration of 4.5g/hm2 was more favorable for the deposition of the waxy content of cotton leaves.The correlation among photosynthetic rate,SPAD and wax were analyzed,and it was found that there was a significant correlation among the three,indicating that the SPAD value increased and the leaf wax content of the leaf was favorable for effective photosynthesis.Therefore,the appropriate concentration of DPC can effectively promote the photosynthesis of cotton leaves and which was increasing the thickness of cotton to promote the accumulation of wax content,the cotton leaves were not conducive to Aphis gossypii feeding sucking behavior.2.The effects of DPC and Aphis gossypii on the secondary metabolites in cotton leaves and soaking seeds with DPC on cotton seed pigment glands and gossypol content number were studied.The results showed that the DPC could induce cotton producing the secondary metabolites of phenolic acids and the concentration of 4.5g/hm2 was the most important factor in cotton.the concentration of soaking seeds with 200mg/L of DPC promoted the cotton seed to produce resistant substances gossypol to resist the cotton seed germination process suffered pests and diseases,but DPC had no effect on the number of pigment glands.The Aphis gossypii fed cotton leaves to the content of secondary metabolites of phenolic acids of cotton leaves and the population of Aphis gossypii increased.The synthesis of phenolic acids secondary metabolites which was found that the induction effect of DPC was greater than Aphis gossypii.Indicating that exogenous hormones regulated the growth of cotton in the process and combination of cotton endogenous hormones induced cotton self-starting defense behavior and producing the harmful secondary metabolites to enhance cotton resistance.3.The effects of DPC treatments with different stages of cotton on the larvae and adult feeding intake of Aphis gossypii were studied.The results showed that the larvae and adult Aphis gossypii diets feeding amount were reduced after spraying the DPC on cotton in different periods.The dietary intake of Aphis gossypii become smaller compared with the greater concentration of DPC treatment and the greatest impact on the larvae.4.The effects of DPC on the contents of triglyceride,total sugar,free amino acid,protein and digestive enzymes in Aphis gossypii were studied.The results showed that the content of triglyceride lower than in Aphis gossypii compared with the blank group but which was decreased gradually with the increase of the concentration of the condensed amine.The content of total sugar,free amino acid and protein higher in comparision with the control group.The amino acid and protein of content were highly similar.The concentration of different condensed amines had some effect on the activity of amylase,sucrase and trehalase in Aphis gossypii but which was not significant..The results showed that the Aphis gossypii absorbed the body fat energy substances resistance the stress of the DPC and the sugars,but free amino acids and protein energy substances accumulated in the Aphis gossypii at the same time to maintain the normal life.