Abstract: The study on the effects of different shadinglevel at blossoming and boll-formingstages on cottonfiber quality ofZhongmiansuo No.41 and Lumianyan No.18 showed that withincreasing shading,the maxi mumfiber length ofcotton decreased,while the elongation period increased. The fiber length in 70 %shading treatment was 1.01mmshorter than that in 40 %shading treatment. Without shading,the fiber reached its maxi mumlength 25days after anthesis,while in shading treatments,the fiber reached its maxi mumlength 35 days after anthesis.Fiber gauge tenacity was also decreased with increasing shading. Comparing with the control,both 40 % and70 %shading significantly decreased the fiber maturation and maturity. Two test cotton varieties presented thesame change trend under shading condition.

Key words: 　Cotton, Blossing and boll-forming stages, Shading, Fiber Quality