Studies On Resistance Mechanism Of Cotton Germplasm To Pectihcphora Gossypiella And Tetranychus Cinnabarinus

Pectihcphora gossypiella and Tetranychus cinnabarinus are the two main pests in cotton,comprehensive management measures based on the cultivation of insect-resistant varieties were the mainly methods adapting to resistant to these two pests.Researching and analysis the resistance mechanisms of cotton germplam to Pectihcphora gossypiella and Tetranychus cinnabarinus,were of some theoretical and practical significance for development new insect-resistant varieties and new drug and cloning insect-resistant genes.This study includes three aspects:Identification resistance behaviors and merchnism of 100 cotton germplasm resources to Pectihcphora gossypiella and Tetranychus cinnabarinus.The main experiment results are as follows:1.The results of 100 cotton germplasm resources resistant to Pectihcphora gossypiella:20 cotton germplasm resources with anti-level,and 22 cotton germplasm resources with mid-anti-level,summing up to a 42%with resistance to Pectihcphora gossypiella,33 with susceptible-level and 25 with high-susceptible-level.The identification results of 100 cotton germplasm resources resistant to Tetranychus cinnabarinus:18 with anti-level and 49 with mid-anti-level,accounting for 67 percent resistance to Tetranychus cinnabarinus,32 with susceptible-level and 1 with high-susceptible-level.The results indicate that comparatively progress have been made in cotton insect-resistant.2.Simple correlation analysis for the resistance of cotton germplasm against Pectihcphora gossypiella showed that notable correlation between the No.of live insects per bell with the thickness of bell epidermal cells and tannin content,and other indicators was not significant.Path and multiple recession analysis revealed that,the No.of live insects per bell were negatively correlated with tannin content and the thickness of bell epidermal cell,but positively correlated the gossypol content,sugar content and the density of leaf hair.And the comparison of the affect on the resistance against Pectihcphora gossypiella was:the thickness of bell epidermal cells＞gossypol content＞the density of leaf hairs＞the sugar content＞the tannin content.3.Simple correlation analysis for the resistance of cotton germplasm against Tetranychus cinnabarinus showed that that the harm index was significant associated with the sugar content,tannin content and leaf thickness,but notable correlated to the thickness of epidermal cells,and other indicators were not significant.Path coefficient through analysis indicated that the comparison of of different indexes impact on the resistance against tetranychus cinnabarinus was:tannin content＞leaf thickness＞the density of leaf hairs＞gossypol content＞the sugar content＞the thickness of leaf epidermal cells.In all,the resistances of cotton germplasm against Pectihcphora gossypiella and Tetranychus cinnabarinus were associated with the physiological and biochemical indexes.They directly or indirectly,or jointly affect the growth,feeding,and reproduction of Pectihcphora gossypiella and Tetranychus cinnabarinus.However,these indexes might have to achieve a certain level(threshold) so that the single insect-resistant role in the resistance targets would be remarkable.Insect-resistant is a comprehensive traits,in addition to shape and physiological and biochemical indexes,the compensation level of germplasm,pest situation also have some contact.