Effects Of Density On Boll-forming Spatial And Temporal Distribution And Yield Formation Of Short-growth-duration Direct Seeding Cotton

In this study,the early maturing conventional cotton variety JX0010 was used as the test material.In the short-season direct seeding cultivation mode,five density treatments were set(A1:30,000 plants/hm~2,A2:60,000 plants/hm~2,A3:90,000plants/hm~2,A4:120,000 Plants/hm~2,A5:150,000 plants/hm~2),the effects of density on the temporal and spatial distribution of cotton boll formation,plant type structure,photo synthetically active radiation,light transmittance,leaf area index and yield formation were studied.The main findings are as follows:1.Different densities show that the intensity of individual plant buds at different time periods firstly rises and then decreases.The flowering intensity per plant shows the trend of first decrease and then increase and then decrease as the density increases.The number of bolls formed on fruit branches was the largest,and the proportion was greater than 10 fruit branches.The longitudinal boll formation of each treatment was A5>A4>A3>A2>A1.The density had a significant adjustment effect on the lateral boll formation of cotton.2.Different density treatments have significant differences in the height of the first node of the fruit branch of the cotton,the position of the first fruit branch,the length of the main stem node,the length of the fruit branch and the length of the fruit node.After the planting density increases,the position of the first fruit branch of the cotton increases and the fruit branch It becomes more aggressive and the plant type becomes compact.The fitting equation of the number of fruit branches of cotton is y=-0.817x+12.545,R~2=0.9818.The number of fruit nodes and the ratio of node to branch all decrease with the increase of planting density.The difference between the treatments is significant,and most of them reach extremely significant levels.3.The upper light transmittance and the lower light transmittance of the cotton population under each treatment showed a trend of decreasing first and then increasing with the growth period,and decreased with the increase of density.At different periods,the central PAR value and the lower PAR value of each treatment group showed a decrease with increasing density,and the differences between most treatments reached a significant or extremely significant level.The leaf area index(LAI)of each treatment showed a trend of increasing first and then decreasing with the growth period.In each growth period,the LAI value increased with the increase of density.4.The number of bolls per plant decreased with the increase of density,and the total number of bolls increased first and then decreased with the increase of density.The fitting equation y=-4.3193x+27.023,R~2=0.9177,the highest total number of bolls under A4 treatment was 1.164 million/hm~2.Different density treatments had no significant effect on single boll weight,seed finger and clothing content of cotton plant upper,upper and lower parts.5.In the density range of 30,000 plants/hm~2 to 90,000 plants/hm~2,the bell formation rate decreases with the increase of density,and within the density range of120,000 plants/hm~2 to 150,000 plants/hm~2,the bell formation rate shows a gradual increase trend.There was a significant difference between treatment A1 and treatments A2,A3 and A5,and there was no significant difference between treatments A2,A3and A5.The seed cotton output increased first and then decreased with the increase of density.The lint cotton output performance was not obvious.The output of treatment A4 reached the highest.The theoretical seed cotton output and theoretical lint cotton output were 5873.81kg/hm~2 and 2158.04kg/hm~2,respectively.