Effects of Planting Ways and Sowing(or transplanting)-date on the Boll Developm ent of the Summer Cotton in Wheat-Summer Cotton Double Cropping A Simulation Model for Boll Growth, Development and Abscission in Cotton Boll Development Characteristics for High-Quality Upland Cotton Cultivars Effects of Sowing Date on Accumulation and Distribution of Biomass and Nitrogen in Cotton Bolls Effect of Shading at Different Developmental Stages of Cotton Bolls on Cotton Fibre Quality