Effects Of Ethephon On Boll Weight And Fiber Quality And Its Relationship With Boll Period

The concentrated boll opening of cotton is a necessary prerequisite for the realization of mechanical harvesting.The application of ripening agent shortens the boll period of cotton,but it also affects cotton yield and fiber quality to a certain extent.Based on this,according to different developmental stages of cotton bolls,this study set different spraying times of ethephon,the ripening agent,measured the dry matter and fiber quality of each component of the boll system,and analyzed the various organs of the boll system under the condition of ethephon Changes in dry matter,clarifying the relative contributions of main stem leaves,fruit branches and leaves and boll hulls to the development of cotton bolls in the process of photosynthetic transport,clarifying the quantitative relationship between the shortening of boll period and boll weight and fiber quality,which is the basis for cotton ripening and boll concentration.The flocculation technology provides a theoretical basis.The main findings are as follows:1.Ethephon affects the transport of photosynthetic products in cotton boll leaf system and its relationship with boll weightThe boll stage was significantly shortened by 3.5-5.7 d under the influence of ethephon.At 5 d after spraying ethephon,the fiber weight of a single boll decreased by 0.20 g compared with the control,and when the boll was split,it decreased significantly by 0.37 g compared with the control.After spraying ethephon,the weight of cottonseeds decreased significantly by 0.24 g compared with the control when the bolls were split.At 5 d after spraying,the transport amount of fiber and boll hull decreased by 0.21 g and0.08 g,respectively,compared with the control;at 16 d（split boll）,the transport amount of fiber and cottonseed was significantly decreased by 0.37 g and 0.26 g compared with the control.Ethephon promotes the transport of assimilated substances from boll hulls to fibers and cottonseeds,and boll hulls contribute15.65%to 18.27%to single boll weight.It is estimated that when the weight reduction per boll is controlled at 0.30 g,the boll period of spraying ethephon should be 35.41-44.91 d.2.Effect of ethephon on fiber quality and its relationship with boll periodThe fiber length was not significantly affected by ethephon,and the damage was mainly concentrated in[-2,0]mm.The specific strength at break was significantly affected by ethephon,and the damage ranged from-9.13 to 2.45 c N/tex.When the spraying time R_d/bwas 0.82,the proportion of micronaire value grade A after spraying ethephon reached 36%,indicating that the spraying ethephon could improve the micronaire value.According to the fitting equation,when the fiber length or specific strength damage is0.30 mm or c N/tex,it can be selected to spray ethephon between 42.54 d and 50.33 d of boll period.Although the application of ethephon can significantly shorten the boll period,the cotton fiber quality will also decrease.3.Cultivation techniques of machine-picked cotton ethephon to accelerate ripening in XinjiangBoll period and boll weight were significantly positively correlated with fiber quality,and the damage to cotton fiber quality by ethephon was greater than that to boll weight.To ensure that the damage to boll weight is reduced as much as possible,if the damage amount is controlled within 5%,the boll period should be greater than about 54.77 d,and the boll period should be greater than about 39.43 d when spraying chemicals;Controlling within 2%,the boll period should be controlled at about 38.09～43.06 d when spraying chemicals,and the spraying time of ethephon can be controlled within August 24-29.To ensure that the top cotton bolls are mature and boll-opening,the top cotton bolls can be sprayed with ethephon when the period of the top bolls is 36.47～41.53 days.The spraying time of ethephon should be from September 2 to 7.