Study On The Coordinated Regulation Of Cotton Growth By Flumetralin And Mepiquat Chloride

Cotton is an important economic crop,which has the characteristics of unlimited growth,plastic plant type and so on.The use of plant growth regulators in cotton can shape the plant type and replace manual topping,which is of great significance to realize the chemistry and mechanization of cotton production.In this paper,two kinds of plant growth regulators,Flumetralin and Mepiquat chloride,were selected to study the effects of mixed concentration and application time on the plant type structure and economic characters of cotton.the suitable application time and mixed concentration were selected to provide guidance for the chemical control technology of machine-harvested cotton.The main results are as follows:1.The effects of application time of Flumetralin and Mepiquat chloride on plant type and economic characters of cotton showed that the plant height and leaf branch growth of cotton after application Flumetralin and Mepiquat chloride were lower than those of the control,the growth of plant height and leaf branch growth decreased with the prolongation of the interval between the two treatments time.The distance between the first,second and third main stem nodes of cotton was significantly shorter than that of the control(P<0.05);the length of the first,second,third and fourth fruit branches of cotton was 61.57-70.57%shorter than that of the control;the number of bolls in different parts of each treated cotton is from lower to middle,upper.With the shortening of the interval between two treatments,the boll number and boll weight per plant increased,while the boll weight per plant topped on July 15 decreased.The interval time between two applications had a certain effect on micronaire value and fiber length.The results showed that the plant type of cotton could be well regulated by spraying Flumetralin and Mepiquat chloride,and had the potential to increase production.According to the yield of seed cotton and lint cotton,the effect of self-capping could be achieved by twice application on June 30 and July 10,which was helpful to the formation of high light efficiency population.2.The effects of the mixed concentration of Flumetralin and Mepiquat chloride on the plant type and economic characters of cotton were studied.The results showed that the plant height and leaf branch growth of cotton decreased at different levels after the mixed spraying of Flumetralin and Mepiquat chloride.The increase in the number of fruit branch moss and bolls in different parts increased at different levels.The regulatory effects of Flumetralin and Mepiquat chloride on cotton were different,among them,the main role in the regulation of cotton plant height is Mepiquat chloride,the concentration of two applications is 90 g/hm~2,45g/hm~2;The main regulating role in the number of leaf branches and fruit branches is Flumetralin,and the first application of Flumetralin mainly plays a role,the concentrations are 750 g/hm~2and 450 g/hm~2,the main regulating effect on the number of bolls in various parts of cotton is Flumetralin,1200 g/hm~2 Flumetralin has a significant effect on the middle boll(P<0.05),900g/hm~2 and 1050 g/hm~2 Flumetralin respectively the upper boll and lower boll have significant effects(P<0.05);seed cotton yield and lint yield have a greater impact under the action of 900g/hm~2 Flumetralin and reach a significant level(P<0.05).At the same time,the fiber length,micronaire value and specific strength of cotton all change under the action of each agent.It shows that the effects of Flumetralin and Mepiquat chloride on the role of each agent in regulating cotton are different.Based on the consideration of cotton economic benefits,it is recommended to apply 600 g/hm~2 Flumetralin+30 g/hm~2 Mepiquat chloride for the first time,the second time application of 900 g/hm~2 Flumetralin+90 g/hm~2 Mepiquat chloride.3.The effects of Flumetralin and Mepiquat chlorid on POD、SOD activity and MDA content in cotton leaves showed that with the prolongation of the time after the application of Flumetralin and Mepiquat chloride,the activities of POD and SOD in cotton leaves increased first and then decreased,while the MDA content increased.The POD activity in the leaves of the chemically regulated group was always lower than that of manual topped cotton,and there was a significant difference(P<0.05)compared with the POD activity in the leaves of the manual topped cotton at 21 d and 28 d after application.There is no difference between the groups.The activity of SOD enzyme in the chemical control group was significantly different from that of artificial topping at different time periods after application(P<0.05),and the application concentration of Flumetralin and Mepiquat chloride had no effect on the SOD activity in the leaves.The content of MDA in the leaves of the chemical control group was always higher than that of manual topping,and the treatment with the concentration of 1200g/hm~2 Flumetralin+135 g/hm~2 Mepiquat chloride was the highest.From the above research results,The plant height,fruit branch length and node spacing of cotton were inhibited after spraying Flumetralin and Mepiquat chloride,which could shape the compact plant type and increase the photosynthetic area of individual and population,and the moss number of fruit branches showed an increasing trend,which made it transform from vegetative growth to reproductive growth,promoted the formation of reproductive organs,and made the boll in different parts effective distribution;the activity of related protective enzymes in the leaves increases in a short time;the number of bolls per plant increased and the yield increased.