Effect of Maturity on the Cotton Boll Development of the Field Planting Cotton under 3-2 Cotton-wheat Double Cropping System

The results showed that the middle maturity cotton boll weight was heavier than that of the earlier middle maturity. Fiber development difference among varieties showed the law that ealier middle maturity varieties were much earlier than that of the middle ones. As to the effect of varieties on fat accumulation in cotton seed(kernel),the earlier middle maturity varieties were more sentisive than that of the middle ones,but the accumulation of protein was just contrary.Effect of varieties on the accumulation of fat acid was small, the middle maturity varieties was advantage of earlier middle maturity varieties as to cotton kernel amino acid accumulation. The varieties seletion under the field planting method with 3-2 model should be determined according to the sowing date.