Evaluation Of Drought Resistance And Analysis Of Genetic Diversity In Cotton Varieties Under Drought Stress Of Seedling Stage And Flowering Stage

This study selected30varieties of cotton as the research object, and carried on the drought resistancecomprehensive evaluation, through the different growth period of drought stress, will be needed for cottonvarieties from the physiological indexes of drought resistance, agronomic traits and yield components ofeconomic characters, the cotton fiber quality three aspects,and used the SSR molecular markers for geneticdiversity analysis and clustering analysis, to extract the more high quality cotton germplasm resources ofdrought resistance from30varieties, as well as the screening of drought resistance evaluation index,explored the drought-resistant mechanism of different growth period of cotton, and to reveal theirrelationship from the perspective of heredity, as for the future of cotton germplasm resources collection andcotton breeding to provide a reference basis, as a result, specific as follows:1. The indexes under drought stress change rule: under drought stress, the proline content and SODactivity and MDA content were increased with the extension of drought stress time, were reduced afterwater, leaf water potential and water content was reduced firstly then rised; Under drought stress, the cottonplant height, the height of beginning section, branch number, boll number and the lint percent weesuppressed, and the number of beginning section did not change significantly under the stress of seedling,but reduced under flowering stress, single boll weight increases under seedling stress, but the change is notobvious under flowering stress; Fiber quality traits variation is not obvious.2. The relationship of drought resistance and various indicators: correlation analysis showed that theproline content and SOD activity, water potential, water content, plant height, branch number, boll numberper, single boll weight, lint percent, fiber length, fiber breaking tenacity, uniformity and the parameters ofthe spinning stability were positive correlation with drought resistance, MDA content, the height ofbeginning section, the optimal micronaire, fiber maturity, rate of short fiber were negative correlation withdrought resistance, the number of starting section and the percentage elongation under the stress of seedlingstage, were negatively correlated with drought resistance, under the stress of flowering were positivelycorrelated, fibre moisture content in the seedling stage was positively correlated with drought resistance,under the stress of flowering was negatively correlated.3. Screening of drought resistance index: based on the significant relationships of each index withdrought resistance, this study took indexes related to drought resistance significantly as drought resistanceevaluation index. Seedling drought resistance evaluation index: proline content and SOD activity, MDAcontent, plant height, node number, branch number, boll number per, single boll weight, fiber length, fiberbreaking tenacity, uniformity, rate of short fiber and the spinning stability parameters; Flowering: prolinecontent, water potential, water content, plant height, branch number, boll number per, single boll weight,fiber length, fiber breaking tenacity, micronaire, uniformity, stable rate of short fiber and the spinningparameters.4. Drought resistance evaluation: through the subordinate function analysis and grey correlationanalysis with the drought resistance index of30varieties, the results of drought resistance evaluation areobtained. The drought resistance varieties used with the evaluation of physiological indexes, strong droughtresistance varieties under seedling stress: C6015, Hai92-4, Zhong Mian Suo49, Zhong Mian Suo50,Zhong07etc; Flowering: Xin Hai20, Zhong Mian Suo49, Xin Lu Zao13, Ji Zha81, KK1543etc; Thedrought resistance type through economic traits, strong drought resistance varieties under seedling stress:C6015, Kui85-174, Ji Zhua Mian, Ji Zha81, Shi Yuan321etc, Flowering: Shi Yuan321, Zhong MianSuo07, Kui85-174, Tu76-94, Ji Zhua Mian etc; The drought resistance type through fiber quality, strongdrought resistance varieties under seedling stress: Xin Lu Zao13, Tu76-94, Zhong Mian Suo07, Xin LuZao1, C1470etc, Flowering: Xin Lu Zao1, Zao13, Guan Nong1Hao, Liao18, Xin Hai20etc.5. Genetic diversity analysis: through the method of SSR marker of26copies of the cotton plantresources for genetic diversity analysis, the genetic similarity coefficient of varieties was between0.32-0.91, the genetic similarity coefficient over0.76between varieties more accounted for54%, the geneticsimilarity coefficient under0.45only accounted for3%, so in this study, the genetic relationship of cottonvarieties is close, at the narrow genetic basis;26copies of materials can be divided into three categories byUPGMA method, all first class4material for sea island cotton; The second category of a total of20materials, all of upland cotton; Third class2materials, chicken feet cotton and tashkent1respectively.