Study On The Occurrence Rule Of Cotton Verticillium Wilt And Resistance Of Cotton Varieties In Xinjiang

In this study, the relationship between disease index and climate condition, resistance of cotton varieties, means of irrigation, kinds and amount of fertilizer, pathogenicity and relative quantity of Verticillium strains etc were investigated. It was suggested that cotton Verticillium wilt only had one peak in whole growth period in Xinjiang, which is obviously different from the result of other provinces. It was also indicated that the occurrence of cotton Verticillium wilt had close relationship with the climate condition in Xinjiang, such as temperature, relative moisture, rainfall, etc. Among them the relative moisture, rainfall were correlated positively with occurrence of cotton Verticillium wilt, especially days of rain and the amount of rainfall influented disease index greatly. Temperature was also a important factor on verticillium wilt, it favored the occurrence of disease when temperature was between 23-26℃in July. The occurrence of cotton Verticillium wilt was also closely related to variety resistance, and the disease incidence was lower when planting the resistance varieties than planting the susceptible ones. The cotton Verticillium wilt was more serious in the drip irrigation than in the furrow irrigation condition. The kind and the mount of fertilizers affected the occurrence of Verticillium wilt. In general, with the increase of the nitrogen, cotton Verticillium wilt became more serious, and with the increase of the phosphorus, this disease took a downward trend. The result suggested that the relationship between kalium and disease occurrence was unconspicuous, which was possibly for the native kalium rich in soil of Xinjiang.Pathogenicity and quantity of Verticillium strains used affected the disease index too. The more strong of the strain, the high occurrence of this disease. With quantity of the spores used to inoculate increased from 104 to 107 spores/ml, the occurrence of cotton Verticillium wilt was increased too, with maximal at 107 spores /ml.The results of the cultivars resistance in three years demonstrated that the majority of upland cotton varieties and materials were sensitive or highly sensitive to Verticillium dahliae, but some varieties and materials exhibited certain resistance. The results also illustrated that long-staple cotton were resistant or highly resistant. So addition to strengthen breeding the resistant cultivars in upland cotton, rational arrangement of the variety in districts where land cotton and long-staple cotton mixing cropped should be adopted in order to alleviate cotton Verticillium wilt. In addition, results of physiological biochemistry of the sensitive and resistant cotton material indicated that the resistance of cotton varieties was closely related with the activity of peroxidase and polyphenoloxidase and phenylatanine ammonia-lyase enzyme.