Effects Of Seed Spheroidization,Sowing Density And Sowing Date On Growth,Yield And Quality Of Direct Seeding Cotton

It is one of the important measures to ensure the growth and development of crops by pre sowing treatment of crop seeds in order to improve the emergence rate and seedling rate.However,the high production cost and complex process flow of traditional seed pelleting and coating treatment technology hinder its large-scale popularization and sowing.There are still some problems in the application of direct seeding cotton in the Yangtze River Basin,such as rapid loss of components,inability to apply large fertilizer,large medicine into the soil and realizing"multi seed seedling".In view of the ratio of cassava seed,bentonite and attapulgite,the seed modification materials were determined through the selection of cassava seed,starch and attapulgite.The effects of this new technology on the growth and development of cotton seedlings were evaluated through indoor pot experiment,and the effects of different seed treatment,sowing density and sowing date on the growth,development,yield and quality of cotton were explored through field experiment.The main conclusions are as follows:1.Effects of seed spheroidization on the growth and development of cotton seedlingsPot experiment shown that the emergence rate of cotton seeds was 99.17%,the emergence hole rate was 100.00%,and the emergence rate was 40.00 after spheroidizing treatment.Compared with the control,the emergence rate,emergence hole rate and emergence rate were 73.75%,84.20%and 20.33;Significantly increased by 25.42%,15.80%and 96.75%respectively;The SPAD value of cotton seedlings after spheroidizing treatment was 42.48 and that of the control was 40.23;Compared with the control,the SOD activity,POD activity and NR activity of cotton seedlings treated with spheroidization were significantly increased by 33.03%,44.29%and 50.14%respectively.The content of soluble protein,soluble sugar and root activity were significantly increased by 38.89%,56.44%and113.53%respectively;Plant height,dry weight and fresh weight also increased significantly compared with the control;The malondialdehyde content of cotton seedlings after seed spheroidization treatment was significantly lower than that of the control by 26.12%,indicating that the degree of cell membrane lipid peroxidation of cotton seedlings after seed spheroidization treatment was lower,and the degree of cell oxidative senescence was slower than that of the control treatment.2.Effects of seed spheroidization,sowing density and sowing date on cotton growth,yield and qualityField experiment shown that the growth period of cotton was significantly shortened by15～18 days after seed spheroidization,and the emergence rate and emergence hole rate were significantly increased by 19.63%～26.67%and 14.82%～20.74%compared with the control;Among the yield and yield components,seed spheroidization treatment can significantly improve the number and quality of bolls per plant,and then significantly improve the yield of seed cotton and lint,but has no significant effect on seed index and lint percentage;Spheroidizing treatment had no significant effect on cotton fiber quality,but could improve micronaire value to a certain extent;The physiological and biochemical indexes of cotton leaves treated by seed spheroidization were slightly different from those of pot experiment.Seed spheroidization could significantly improve the contents of soluble protein,free amino acids,superoxide dismutase and peroxidase activities of cotton at seedling stage,but seed spheroidization had no significant effect on SPAD value,soluble sugar,proline,malondialdehyde content and nitrate reductase activity in the whole growth cycle of cotton;Seed spheroidization treatment can significantly improve the plant height of cotton at seedling stage,which is slightly higher than that of the control at bud stage,but the difference is small.The number of fruit branches increased significantly by seed spheroidization at the bud stage of cotton,had little effect at the beginning of flowering and Bolling stage,and had no significant difference until boll opening stage.Seed spheroidization had no effect on the initial node height of cotton.High density(45000 plants/hm~2)and low density(30000 plants/hm~2)can significantly shorten the bud stage,boll stage and boll opening stage of cotton,increase the micronaire value of cotton fiber,and significantly increase the yield of seed cotton and lint;In terms of physiological and biochemical indexes of cotton,high density sowing and low density can significantly increase the soluble protein content of cotton at bud stage by 2.08%～5.66%,superoxide dismutase activity at bud stage by 6.38%～9.61%,peroxidase activity at boll opening stage by 18.90%～23.68%,but can significantly reduce the proline content and nitrate reductase activity at boll opening stage.Late sowing(June 5)can significantly shorten the cotton growth period,significantly improve the emergence rate of cotton,and significantly improve the average length of the upper half of cotton fiber quality.Among the physiological and biochemical indexes,late sowing could significantly increase the SPAD value of cotton at bud stage by 1.35%～8.63%,significantly increase the soluble protein content and nitrate reductase activity at boll opening stage,significantly reduce the content of malondialdehyde at seedling stage and bud stage,and reduce the degree of cell senescence of cotton leaves;Late sowing can also improve the agronomic characters of cotton and significantly increase the plant height at seedling stage and flowering and Bolling stage.