Analysis Of The Characteristic And Genetic Diversity Of Some Cotton Varieties In Apricot-Cotton Intercropping System Around The Tarim Basin

Tarim Basin was one of the main areas of planting cotton in Xinjiang, in which the apricot-cotton intercropping had been an important cultivation mode because of its unique environment of geography and climate. The characteristics and genetic diversity of the cotton varieties planted in this mode in Tarim Basin were studied in this paper, which played an important theoretical and practical significance in evaluating cultivation system, selecting cotton varieties and making strategic decision of cotton production in south Xinjiang. In this paper, the effect of apricot-cotton intercropping on the characteristics of growth, production and fiber quality of cotton variety were studied on the basis of the apricot-cotton intercropping system (4mX6m) widely used in south Xinjiang; DTOPSIS method was used to evaluate cotton varieties in apricot-cotton intercropping system, and the relational grade analysis and restoring menstrual analysis were used to study the relation between main characters and yield; RAPD markers was used to assess the genetic diversity of 23 cotton varieties of the intercropping in the Tarim Basin. The main results were as follows:1 The height, LAI, boll weight, boll per plant, branch number, lint percentage, seed cotton yield and lint yield were lower than CK in the apricot-cotton intercropping system, in which the trends of changes were partial distribution tendency with the increase of vertical distance from tree, and treatment1 was lowest, treatment10 was largest. The results of new multiple range method showed that the differences of boll number per plant, branch number, seed cotton yield and lint yield between all treatments and CK were extremely significant, which showed the intercropping of apricot and cotton had great effect on cotton yield.2 With the increase of vertical distance from the apricot, the trends of change of fiber length, uniformity, strength, elongation, reflectivity and CSP were partial distribution tendency in the apricot-cotton intercropping system, and the yellowness was opposite; The fiber length, uniformity and reflectivity were largest in treatment10, strength, elongation and CSP were largest and yellowness was lowest in treatment9, M value was at A-level in treatment8, 10 and 11. Compared with the control, the uniformity and elongation in all treatment was lower than CK, and all fiber quality traits measured in treatment1-6 were lower than CK (yellowness contrary), the results showed intercropping of apricot and cotton had great effect on cotton fiber quality.3 DTOPSIS method was used to evaluate cotton varieties in apricot-cotton intercropping system which showed among the five cotton varieties tested, Zhongmian43 was the most suitable cultivars and Zhongmian49 was not appropriate to plant in the apricot-cotton intercropping system.4 In the apricot-cotton intercropping system, the differences of coefficient of variation among cotton agronomic and fiber quality characters were significant, and the order of stability of agronomic and fiber quality characters were: growth period> lint percentage> LAI> boll weight> branch number> boll per plant> height> bud number, and uniformity> fiber length> reflectivity> CSP> strength> elongation> M value> yellowness. The relational grade analysis and restoring menstrual analysis showed the correlation sequence between agronomic characters and lint yield was: boll per plant> boll weight> branch number> bud number> lint percentage> height> LAI> growth period, which between fiber quality characters and lint yield was: strength> uniformity> CSP> reflectivity> yellowness> M value> fiber length> elongation. The uniformity was a leading factor that affected fiber length, elongation, reflectivity and CSP, and elongation was a leading factor that affected M value. Boll per plant and strength played the most comprehensive and direct role in the lint yield.5 The result showed that a total of 70 arbitrary primers were screened using RAPD markers with the 23 cotton species and finally 27 primers which could produce steady polymorphism were obtained. 136 polymorphic bands were amplified and the polymorphic rate was 67.3%; Cluster analysis revealed that these 23 cotton species could be divided into 2 classes and 5 subclasses; The mean similarity among 23 cotton varieties of the intercropping was 0.665, which less than 0.50 was only 6.7%, which showed there was a low level of genetic diversity among these cotton varieties of the intercropping in the Tarim Basin.