Machine Picking Cotton Planting Modes On The Formation Of Cotton Yield And Effects Of Defoliation

Currently,six-lines machine picking cotton planting modes were widely used in the field.However,the problem of low effect of defoliation for middle and lower leaves leaded to high rate of impurity in harvested cotton,so there was fiber length loss after repeated cleaning process and the seriously declined quality of cotton.The appropriate planting pattern was one of the effective ways to solve the problem of the quality of cotton picking and to reduce the cost of cotton planting.This study used XLZ No.54,a loose type cotton,and XLZ No.75,a compact type,as the materials,and three machine cotton modes were used in the current field conditions to compare the effects of the following agronomic traits of cotton:including growth and development,canopy structure,photosynthetic matter accumulation and distribution characteristics,yield components,defoliation leaf and fiber quality.This study will be useful for yield and quality of the Nanjiang machine picking cotton.Main conclusions are as follows:1.Identified the effect of machine planting pattern on the machine-harvested cotton growth and photosynthetic material production.Cotton would grow faster if the row spacing get wider and planting distance get narrower.Compared with six-lines pattern,three-lines pattern cotton’s emerging time was 2 days earlier and the development process accelerated in 3～5 days.The height change of three-lines pattern and four-lines pattern were 12.0%～21.5%higher on main stem than six-lines pattern.For the loose type variety,XLZ No.54,the dry matter accumulation and and the proportion of vegetative organs and the proportion of inner cotton boll of three-lines pattern were the highest.For the compact type variety,XLZ No.75,the dry matter accumulation and and the proportion of vegetative organs and the proportion of inner cotton boll of three-lines pattern were the lowest.The proportion of middle and upper cotton boll of three-lines pattern were higher than others.The proportion of under cotton boll of six-lines pattern were higher than others.2.Clearly analyzed the machine planting pattern on the machine-harvested cotton canopy structure and photosynthetic characteristics of yield.Three-lines pattern’s LAI maximum value was higher 0.7～1.1 than four-lines modes,the leaf inclination angle was 3～6°higher than others.The Pn of loose type varieties three-lines pattern was higher 1.81～8.13%than six-lines and four-lines pattern’.There was no significant difference among three patterns of the Pn for compact type varieties..For XLZ No.54,both the yield of three-lines pattern and four-lines pattern were higher than six-lines pattern.Compered with six-lines pattern,the seed cotton of three-lines and four-lines pattern increased 10.0%and 7.2%,the lint yield increased 8.9%and 7.8%.For XLZ No.75,the seed and lint cotton yield of six-lines pattern was the highest.Compered with six-lines pattern,the seed cotton of three-lines and four-lines pattern declined 8.2%and 5.8%,the lint yield decline 8.9%and 7.8%.3.Identified the effect of machine planting pattern on the machine-harvested cotton defoliation and quality.There was a very significant correlation between branch complexity coefficient and defoliation rate.Ifα₁was large,the defoliation rate would be small.Compared with six-lines pattern,for XLZ No.54,the defoliation rate of three-lines patterns increased 2.54%and hanging rate increased 4.08%.For XLZ No.75,the defoliation rate of three-lines patterns increased 2.54%and hanging rate increased 3.61%.The mainly effect of machine planting pattern on the quality of cotton fiber is the cotton boll in the outward and upper.The three-lines pattern and the four-lines pattern outward boll fiber quality is higher than that of four-lines pattern.4.Clearly demonstrated the best machine planting pattern on the machine-harvested cotton in Nanjiang for different types.It should be payed more attention on matching varieties with good patterns.For loose plant type variety,three-lines machine picking planting pattern has higher yield and better defoliation effect because of high yield and high quality.But for compact plant type,four-line mode was more suitable in machine harvested picking.For compact plant type cultivar,the best machine picking planting pattern was four-lines modes,three-lines machine picking planting pattern was not the best choice.