Study On The Effect Of DPC Compound Capping Agent On The Plant Shaping And Yield Of Machine-harvested Cotton

Chemical regulation is an indispensable technical component of cotton production,cotton chemical control technology has matured,in recent years,the research on cotton chemical control is mainly concentrated in DPC,chemical capping,defoliation and ripening,etc,but the interaction of DPC and capping agent on the influence of machine cotton plant shaping and yield has rarely been reported.In view of this,this paper studies the influence of DPC and topping method on the shaping and yield of machine-harvested cotton plants,and set up 2 DPC treatments and 3 topping treatments in Awati County,southern Xinjiang,the main cotton-producing area,with DPC treatment as the main area,namely: spraying DPC(H1),non-spraying DPC(H0);topping treatment as a sub-area,namely: topping agent spraying(D1),artificial topping(D2)and non-topping(D3).In this paper,through the study of DPC compound topping agent on the growth process,plant type,canopy structure,photosynthetic characteristics,aboveground dry matter accumulation and distribution,yield and fiber quality,etc,this paper aims to provide theoretical guidance for the construction of the whole process of mechanized cotton mining in the southern Xinjiang cotton area.The main findings of the paper are as follows:1.The effect of DPC compound topping agent on the growth process and plant structure of machine-picked cotton.Spraying DPC can make the whole growth period of cotton earlier,the H1 treatment is 5 days earlier than the H0 treatment,and the D1 treatment is 3 days and 5 days earlier than the D2 and D3 treatments.Compared with the H0 treatment,the H1 treatment reduced the plant height and the daily growth of the main stem of cotton,and spraying DPC would reduce the internode length of the main stem,the number of fruit branches,the length of fruit branches,the angle between fruit branches and the plant width,so that the cotton plants are more compact.The plant height of D1 treatment is slightly higher than that of D2 treatment,but there is no significant differences.In addition,D1 treatment can further optimize and shape the plant structure of cotton.Compared with D2 treatment,the upper fruit branch length,fruit branch angle and plant width of D1 treatment decrease respectively 60%,11.1%,26.9%.Under the condition of spraying DPC,the plant structure of cotton treated with D1 was more reasonable.2.The effect of DPC compound topping agent on the canopy structure and photosynthetic characteristics of machine-picked cotton.Under the condition of benzylamine,compared with H0 treatment,H1 treatment can reduce cotton LAI and prevent cotton from flourishing;while H1 treatment can significantly increase cotton MFIA,TC,chlorophyll SPAD value and Pn compared with H0 treatment,and the increase rates are: 16.0,25.5%,8.9%,18.1%;D1 treatment can significantly increase cotton MFIA,TC,chlorophyll SPAD value and Pn compared with D2 treatment in the topping method,the increases are: 16.9%,11.0%,16.1%,3.2%,10.9%,the leaf area index was D3>D1>D2;under each treatment,DPC compounded with topping agent could better shape the canopy structure suitable for machine-picked cotton harvesting and the photosynthetic characteristics suitable for high cotton yield.3.The effect of DPC compound topping agent on dry matter accumulation,yield and quality of machinepicked cotton.The compound topping agent of benzylamine can inhibit the vegetative growth of cotton and promote the growth of cotton reproductive organs.In the flocculation stage,the accumulation of vegetative organs in H1 treatment decreased by 28.0% compared with H0 treatment;the accumulation of reproductive organs in D1 treatment increased by 17.8% and 50.0% on average compared with D2 and D3 treatments.The effect of DPC treatment was mainly reflected on cotton fuqian peach,and the effect of topping treatment on cotton was mainly reflected on Fuqian peach.Under the condition of spraying DPC,the upper boll in D1 treatment decreased by 0.6,but the middle boll increased by 0.8.Both the spraying of DPC and the topping agent will increase the number of bolls per plant and boll weight of cotton,and ultimately increase the yield of cotton.The lint yield of cotton was the lowest in H0D3 treatment,and the highest in H1D1 treatment.Compared with H0D3 treatment,the lint yield of H1D1 treatment increased by 101.8%.The overall performance of cotton lint yield of each treatment was D1>D2>D3.The lint yield of H1 treatment increased by 43.3% on average compared with H0 treatment.Therefore,topping treatment needs to maintain a relatively ideal yield under the corresponding chemical regulation.There were no significant differences in the average length,uniformity,strength and elongation of the upper half of the cotton overall between treatments.