Effects Of Different Defoliants And Their Influence On Cotton Yield And Quality

Xinjiang has become my country’s main cotton producing area with its unique environmental conditions and resource advantages.In recent years,in order to reduce labor costs and tap the potential of increasing cotton production and income,machine-picking cotton technology has been rapidly developed and widely popularized in Xinjiang,especially the XPCC.Accelerating the development of the whole process of mechanization of cotton production in southern Xinjiang is an effective measure to reduce production costs and improve the efficiency of cotton planting.Chemical defoliation is a technology that prompts most of the leaves of cotton plants to fall off as soon as possible before harvesting,so as to improve the efficiency of mechanical harvesting and reduce the impurity rate of seed cotton,and the direct effect of defoliants and the field after defoliation The improvement of ventilation and light transmission has promoted the cracking of cotton bolls.Chemical ripening is the application of ripening agents to solve the problem of late maturity of cotton.Especially in the harvest season when the climate is abnormally changeable,the chemical defoliation of cotton is implemented to accelerate the ripening to ensure mechanical harvesting.The smooth realization of cotton is particularly important for saving costs and increasing benefits in large cotton areas like Xinjiang,and improving the competitiveness of China’s raw cotton in the international market.In this experiment,a field experiment was set up to compare the effects of different cotton defoliant varieties,defoliant dosage,application time,and defoliant spray on the growth and development,yield,cotton fiber quality and protective enzyme activity of machine-harvested cotton.The establishment of key agronomic techniques suitable for mechanical harvesting of cotton in southern Xinjiang will provide a scientific basis for the widespread promotion of intensive production technology of mechanically harvested cotton in southern Xinjiang.The test was completed in two years.A single-factor randomized block test was used in the 12 th Regiment of Alar City,the First Agricultural Division,Alar Reclamation District,southern Xinjiang.In 2019,the best application time and the best application concentration were screened,and three were set.For the application time,two defoliating agents,Tuoturon and Caituotong were selected,and the effects of different spraying times on the defoliation effect of cotton were studied and analyzed.Two defoliants with three concentrations of Teturonate and Tetrol were set up to study and analyze the effects of different concentrations of defoliants on the defoliation effect of cotton.In 2019 and 2020,four defoliating agents commonly used in cotton fields in southern Xinjiang,Tuoturon,Cituotong,Ruituolong,and Ruihua,were selected for screening tests of different defoliants.The tested variety was Xinluzhong No.88,and the defoliation rate,boll spit rate,boll number per plant,boll weight per plant,protective enzymes,fiber length at different positions,breaking strength and micronaire value of cotton were analyzed by different defoliant agents.,Fiber uniformity,yield,economic benefit and other indicators,record the actual harvested cotton output of each treatment,the basic conditions of the demonstration cotton field,and the weather conditions during the entire experiment.The research got the following results:1.The effect of different spraying time on cotton defoliationThe results of spraying the defoliant at different times show that when the natural boll throwing rate in the field reaches 50%,the defoliation rate will increase quickly and the defoliation rate will be higher.When the boll throwing rate is 40%-50%,spraying the defoliant will affect cotton.Yield and quality have been significantly improved.The boll spit rate is 50%,and the cotton yield increases the most.When the boll spit rate is 60%,the spraying agent has no obvious impact on the yield and quality of cotton.The earlier the defoliant is sprayed,the better the cotton spitting out.It can be seen that the best effect is when the natural boll respiration rate reaches 50% in the field.2.The effect of different defoliant concentration on cotton defoliation effectDifferent concentration treatments have different effects on cotton defoliation.Low-concentration treatments cannot achieve significant defoliation effects.High-concentration treatments increase the sticking rate of coke leaves and increase the impurity content of cotton.The medium-concentration treatments have the best defoliation effect.The agent 900 m L+1 050 m L(ethephon)has a significant promotion effect on cotton production.A dosage of 750 m L per hectare of Tetotong + 750 m L of auxiliary agent has an obvious promotion effect on cotton yield and quality.3.The effect of different defoliant varieties on cotton defoliationThe four defoliants all have good defoliation effects and flocculation effects.Among them,the defoliation rate and flocculation rate of catabolism and trotolon are better,and the defoliation rate and flocculation rate of tromethoxone are the most significant,and the defoliation rate and flocculation rate are the highest.Caituotong is the most stable for cotton quality,and Tuotulong,Caituotong,and Ruituolong have improved cotton yields to varying degrees.The economic benefits of Tuolong and Cao Tuotong are the best.The defoliation rate of Cettoton and Tuoturon is relatively stable within two years.The temperature during the defoliation process in 2019 is relatively high.The defoliation rate of the four defoliants is ≥90%after 25 days after application,and the temperature in 2020 is relatively low.,30 days after application,the defoliation rates of catabolite and tretorone were 93.08% and 97.5%,respectively,and 85.8% and 80.25% for Ruihua and Ruituolong treatments.Within two years,the defoliation rates of four defoliants were 10%.-30 days are significantly worse than the water control(P<0.05).The content of MDA(malondialdehyde)in cotton leaves showed an obvious upward trend 2-6 days after treatment with defoliants,and the rising trend was the most obvious on the 6th day after treatment.The content of MDA in cotton leaves treated with four defoliants was similar to the control.Significant difference(P<0.05);the four defoliants had no obvious effect on cotton boll weight and lint percentage.The catabolism treatment has a significant increase in the length of cotton fiber.After the other three defoliants,the cotton fiber length is not significantly different from the control(P>0.05);the four defoliant treatments have fiber breaking strength and fiber neatness.The influence of micronaire and micronaire value is not obvious.Two years of field trials have shown that Tetulong and Tetulong are suitable for use in the Alar Reclamation Area of Southern Xinjiang.