Abstract: Through the field experiment of flowering, the dynamics of blossoming into boll and optimum boll forming period of cotton direct-seeded after wheat in northern Hubei Province were analyzed. The results showed that the flowering period of cotton direct-seeded after wheat in northern Hubei Province was from July 25th to September 17th,the boll-forming period was from July 25th to September 11th,and the peak boll forming period was from July 30th to September 2nd. The beginning and peak period of blossoming into the boll were advanced or delayed according to the current climate. It was a high boll formation rate and a fast fructification in the early and middle stages of flowering,and the period of daily maximum boll-forming was 10~15 days earlier than the period of daily maximum flowering. The optimum bolling period of post-wheat cotton in northern Hubei Province was from July 25th to August 28th. The summer and early autumn bolls formed in this period were the main parts of post-wheat cotton production in northern Hubei Province,the rangeability of bell weight and ginning outturn were not wide,and the fibre quality met the requirements of the textile industry.

Key words: cotton direct-seeded after wheat, the flowering period, optimum boll forming period, Hubei Province