The Effectof Verticillium Wilt On Yield And Quality Of Cotton And Resistance Of Cotton Varieties

Cotton is the pillar industries of agriculture in xinjiang,but with the extension of continuous years,the disease is becoming more and more serious,Especially verticillium wilt,has become one of the main constraints in cotton production in Xinjiang.Controlling the epidemic and spreading of Verticillium Wilt and breeding resistant varieties(lines)has become an urgent task to ensure the sustainable and rapid development of cotton industry.So to understand the epidemic trend of Cotton Verticillium wilt,suitable cultivation measures and the main varieties of cotton disease resistance,in the absence of resistant varieties(strains),resistant varieties and no lack of effective fungicides Verticillium wilt resulting from the absence of the application of agricultural cultivation measures to control the spread of disease or inhibition of Verticillium wilt,it is of great significance to guide the agricultural production in the field.Therefor,this study was carried out and the following conclusions were drawn:1?Cotton verticillium wilt was general survied in 4 representative typical cotton farms of Shihezi reclamation area.The result showed that 75.47% of the cotton fields area have been infected with different incidence Verticillium Wilt,and area with invaded cotton increased 130.13% over last seven years.Thereinto,invaded cotton area increased 264.24%(incidence in 10.1-20%)and 256.77%(incidence in 20.1-30%).It lead to the vast loss of local cotton production.Therefore,The most efficient and cost-effective method of controlling the disease is the breeding of resistant or tolerance cotton cultivars,the rational distribution of alfalfa varieties,strict block of no disease area,decrease mild area and less seriously area.2? Verticillium wilt impacted cotton yield including boll number of per plant and Single boll weight.Disease also significantly reduces fiber quality following disease severity,including reducing fiber length and fibre uniformity,highing lint percentage,little influencing on fibers elongation percentage,and variring fiber ratio strength with cotton material.3?The cultivation measures are closely related to the cotton Verticillium Wilt.It is necessary to prevent Verticillium wilt appling on agricultural control measures at the present situation of the absence of resistant varieties and other effective diease control meathod,and disease more and more serious in Shihezi.The results showed that the time of cotton sowing,film mulching cultivation and topping not only lowered yield and fiber quality,but also incidenced the severity of Verticillium Wilt.In normal years,the earlier the sowing date,the more serious disease,so the late seeding at appropriate period certain availed controlling disease.Film mulching cultivation not only enhanced the soil temperature and promoted the growth of cotton plant,but also contributed to the survival and infest of Verticillium dahliae.Topping can control the vegetative growth of cotton,regulating vegetative growth with reproductive growth,improving the boll setting rate,but resistance of plant was weakened due to the weakening of vegetative growth.Hence the time of topping was late Verticillium wilt severe.For example,Shihezi reclamation area of cultivatiing early maturing varieties Shi-hui No.11 and No.12,the time of topping in July 5th-10 was beneficial to boll number per plant,yield,quality.4?This paper carried out the research on the relationship between temperature and the occurrence of Cotton Verticillium wilt,This study indicates that vegetate of Verticillium dahliae was inhibited by continuous high temperature during 7,8 months,and then remarkable reducing incidence,especially the higher frequency of ?27 average daily temperature or frequency of daily maximum temperature ??35?,the more inhibiting Verticillium wilt.For example,Verticillium wilt of cotton was obviously alleviated for continuous high temperature during 7-8 months of 2015 in Shihezi.Some of susceptible cotton material were misevaluateed as resistant or tolerance.Furthermore,continuous high temperature will obviously affect the cotton yield and quality,time of high temperature holded longer,the boll retention abccission rate geted higher,boll number per plant was lower,fiber length was shorter,and micronaire and short fiber index was higher.5?In this study,resistant of 17 cotton varieties of north of Xinjiang were evaluated to Verticillium Wilt.the results showed all of 17 tested varieties were without resistant,13 tolerance and 4 susceptible nto the nursery of virulence Verticillium Wilt in 2015,But all of 17 tested varieties were susceptible into the nursery of high virulence Verticillium Wilt in 2016.It is a large difference about 2015 and 2016,There is a big difference in the result of two years' identification,which is caused by the pathogenic pathogenicity of the disease irulence Verticillium Wilt.Therefore,we proposed that Identifying sources of resistance gived preference to test into the nursery of high virulence Verticillium Wilt.Shihezi's climatological data of continuous high temperature weather from July to August in 2015,the condition of Verticillium wilt is alleviated,it further illustrated that identifying sources of resistance must refer to experiment above 2 years.Besides,in this experiment,the resistant stability of resistant materials(10 generations)was also observed,The results show that breeding of resistant varieties to cotton Verticillium Wilt.also must persistence system selection many years.