To investigate the effect of wheat-cotton double cropping system on cotton, planting pattern experiments in field were conducted in 2009-2010, with wheat-cotton intercropping system as control. The indexes of development characteristics and yield component of cotton were analyzed. The results were showed as follows. In wheat-cotton intercropping treatment, the development process was earlier, and the forming of fruit node and boll was longer and more than those of cotton transplanted after wheat harvest. The later autumn boll percent was only 3.2%-4.7% and the rate of blossom before frost was 88.6%-95.7%. The cotton in intercropping system also had high biomass and harmonious relationship between vegetative growth and reproduction. For cotton transplanted after wheat harvest treatments, the dry matters were low and pre-summer bolls were few. For cotton with substrate or nutrition treatment, the forming of fruit node and boll was later and less than those of cotton with intercropping treatment, the late autumn boll percents were 11.8%-20.8%, and the rate of blossom before frost was 77.2%-90.7%. The seed yield of cotton with substrate treatment was lower than that of cotton with intercropping treatment, but higher than that of cotton with nutrition treatment. For direct seeding cotton of medium-matured variety after wheat harvest, the reproductive growth was later and weaker. The forming of fruit node and boll was later and had no obvious peak, which easily caused invalid growth at later stage. The late autumn boll percent was 24.5%-34.0% and the rate of blossom before frost and seed yield were low. For direct seeding cotton of early-matured variety after wheat harvest, the transforming growth from vegetative to reproductive growth was earlier. The forming of fruit node and boll was concentrated with higher peak value and the total dry matter in reproductive organ was higher. The late autumn boll percent was only 3.3% and the rate of blossom before frost was 88.0%. The seed yield was equal to that of cotton transplanted after wheat harvest. As a result, the yield of cotton in intercropping system was higher and more stable, and that of transplanted cotton might be potential, while that of direct seedling cotton depended on the variety characteristics.
