Optimum Planting Density of Hybrid Insect-Resistant Cotton in Cotton Areas along the Yangtze River for High Yield and Quality

[Objective] To observe cotton growth,cotton boll and production at different planting densities and to provide a theoretical reference for reasonable planting density and high-quality high yield cotton along the Yangtze River.[Method] The cotton variety Xiangzamian 8 was used,and its initial density was 12 000 plants/hm2.Density gradient was 9 000 plants/hm2 to set up six treatments.The growth cycle,yield,cotton boll,and characteristics of cotton fiber were observed.[Result] Density did not have significant effect on plant height and growth cycle of cotton.Seed cotton lint percentage and fiber quality were not significantly different between treatments of different densities.However,boll weight,distribution of three-boll,boll abscission rate,stiff and rot boll,and yield were affected significantly.The boll weight and bolls of July 21 decreased with the increase of planting density.The boll abscission rate and percentage of stiff and rot boll increased with the increase of planting density.In addition,the treatment 5 was the worst.The lint yield was highest in the treatment 3 and lowest in the treatment 1,and it was higher in the treatment 2,3 and 4.[Conclusion] The optimum planting density of hybrid insect-resistant cotton is 30 000 plants/hm2 in cotton areas along the Yangtze River.