Effect Of Defoliation On Cotton Boll Development And Fiber Quality Formation In Xinjiang

In recent years,with the rapid growth of labor cost in China,the implementation of cotton mechanical harvesting has become the sustainable development direction of cotton planting industry.Cotton mechanical harvesting can significantly reduce labor intensity and promote the transformation from traditional agriculture to modern agriculture.The chemical defoliation of cotton is a necessary technical measure for the implementation for Cotton mechanical harvesting.It is an important link to improve the working efficiency and the quality of the raw cotton.The application research of the standardized in chemical defoliation for cotton production is of great significance to guarantee the quality of mechanical cotton production,reduce the cost of cotton production and improve the benefit of cotton planting.respectively by defoliating agent at different times.Find the effects of defoliation on single boll yield and fiber quality of cotton.Analyzed the damage degree of fiber weight per boll and fiber quality affected by defoliation.To explore the method to determine the defoliation application time,in order to minimize yield losses and reduce fiber damage.The main results of the study are as follows: 1.Effect of defoliation application times on cotton boll developmentThe maximum theoretical amount of boll shell was significantly reduced with defoliation,and 4.6%~8.5% was reduced compared with the control.However,in different defoliation application times,there was no significant difference between the maximum theoretical amount of the bell shell.The weight of single boll fiber and cotton seed weight has significantly affected by the defoliation,and the earlier application time was,the larger decrease was,the weight of fiber per boll and cotton seed weight applied at 44 days of days post-anthesis was only 2.8% and 6.6% lower than the control,and the difference was not significant,while the application of the days post-anthesis 30 days decreased by 61% and 46% respectively,and the effect on the fiber was stronger.The cumulative characteristics of the single boll fiber weight and cotton seed weight were analyzed,the application of defoliation was significantly affected by the cumulative characteristics before the 37 days of days post-anthesis.The initial time of the rapid accumulation of single boll fibers has 12%~31%(3 ~7 days)was earlier than the control in 37 and 44 days of days post-anthesis.The initial time of rapid accumulation period of cotton seed weight was advance 7.5% and 7.5%(1~4 days).the average cumulative rate of the rapid accumulation period was also significantly different between the fiber and the cotton seed,and the application of defoliation at the days post-anthesis 30 days decreased 14%~38% compared with the control.2.Determination of suitable application time of defoliation catalyst in order to reduce the loss of single boll yieldThe boll period of cotton was shortened with the application of defoliation.With the application time of defoliation advance,the boll period was shorter.When the application time as 44 days of days post-anthesis,the cotton boll period shortened by 2.7 days,and the shortened amount was 0~5 days,about 62%,and the days of days post-anthesis 30~37 days used defoliate,the cotton boll period of 33%~45% was reduced by 5~10 days.The weight of fiber and cotton seed were significantly affected by the defoliation.The reduction of the days post-anthesis 44 days at different application time was the least,0.15 g decreased,and the days post-anthesis 30 days decreased by 40% and 26% respectively.The damage level of single bell fiber and cotton seed was mainly based on [-1.0 g,0 g),and the proportion of [-1.0 g and-0.5 g)increased with the time of application advance,which accounted for 31%~45%.There was a significant linear relationship between the cotton boll period and the damage amount of the single boll yield,and the "defoliation application times/bell period" was introduced to integrate the cotton boll and single boll yield damage to determine the application time of the defoliation.If the controlled the damage of yield less than 0.1 g,the "defoliation application times / bell period" was more than 0.79,and the cotton varieties with 55 days boll period could apply defoliation at the days post-anthesis of 43 days.3.The later stage of cotton growth effected by defoliation on fiber qualityThe effect of defoliation on fiber length is relatively small,and its damage was mainly in-0.5 mm~0.0 mm,and half of them was increase.The fiber strength was significantly affected by the defoliation,and its damage amplitude was larger and concentrated in 4 cN/tex~0 cN/tex,and the damage amplitude was significantly enlarged with the application time,but 61% of the varieties had a tendency to increase when the days post-anthesis of 37 days,and the fiber strength was more sensitive to the defoliate.There was a significant linear relationship between boll period and fiber quality damage.and the "defoliation application times/bell period" was introduced to integrate the cotton boll and fiber quality damage to determine the application time of the defoliation.If the controlled the damage of fiber length and fiber strength less than 0.50,the "defoliation application times/bell period" was more than 0.74 and 0.68.