| Xinjiang is the biggest production base of high quality cotton in China. The quality of cotton planted in Xinjiang is the superexcellent in our country because of the unique climatic condition. At present, cotton production has been the supporting industry of agricultural production in Xinjiang. However, Fusarium wilt and Verticillium wilt in cotton are severe with each passing day along with the fast expansion of planting area and the prolong of repeated tillage, which has been the main barrier of restricting sustainable development of cotton production. In this paper, adopting the methods of identification host, vegetative compatibility, isozyme and PCR specific amplification, the variation of population structure of Fusarium oxysporum f. sp. Vasinfectum and Verticillium dahliae in cotton were studied from the three different levels of soma, protein and nucleic acid. At the same time, the culture character and growth of Verticillium dahliae in cotton were determined. The main result as follows: 1. The races of 40 strains of cotton Fusarium wilt in Xinjiang were identified with the method of identification host. The result shows that all strains identified belong to race 7. Among them, the pathogenicity of 28 strains is strong, which amount to 70.0% of strains identified. Vegetative compatibility of Fusarium oxysporum f. sp. Vasinfectum was determined with the technology of nitrate reductase deficiency. The result shows that the whole tested strains belong to one vegetative compatibility group, which also can compatible with standard strain of race 7 and can not compatible with standard strain of race 3 and race 8. These results show that race 7 is still dominant in cotton Fusarium wilt in Xinjiang and race 3 and race 8 was not found. Compared with previous research, the population components of cotton Fusarium wilt have not changed yet.2. The study of electrophoresis of the soluble protein and isozyme on standard race of Fusarium oxysporum f. sp. Vasinfectum in cotton shows that there has distinct difference among the different races under the protein level. The race 3, race 8 and race 7 have their characteristic band and the three races have the cooperative bands, which points out that there has some similarity among the different races. The band of 25 tested strains of race 7 has higher consistency. Most of the stains have 1 characteristic band of race 7 and several strains have 2 characteristic band of race 7.The clustering scheme and the matrix of similarity coefficient from cluster analysis shows that most of strains have higher similarity to the stains of race 7 and so the consanguinity between them are closer; they have lower similarity to the stains of race 3 and race 8 and so the consanguinity between them are far. For reasons given above, these methods can distinguish that 25 tested strains belong to race 7. The result from these methods is basically consistent to that from the methods of identification host and vegetative compatible group, which shows that the electrophoresis of the soluble protein and isozyme can be an assistant means for the identification to the races of Fusarium oxysporum f. sp. Vasinfectum in cotton.3. The culture character and the temperature experiment of the different stains of Verticillium dahliae in cotton shows that the colony color of each strain of Verticillium dahliae from cotton have two kinds, i.e. gray/black and white/sandy beige. Most of them are gray/black, which amount to 87.5%. Only a few of them are white/ sandy beige. All tested strains can produce microsclerotia. 88.5% strains can produce more microsclerotia. These results show that the sclerotic type of the colony of Verticillium dahliae in cotton from Xinjiang is dominant. The standard strains of Qiang991, Ruo774 and T-9 can produce more microsclerotia and Luo151 and Luo153 cannot produce microsclerotia. All tested stains can grow better at 20℃～25℃ and they grow best at 25℃. At 30℃, the growth is inhibited obviously. Particularly, most of the stains can not grow at 33℃. Only a few strai... |
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