Studies of the effects of different soil water regime on the cotton morphological development and source-sink relationship
were carried out in cotton area of
Huanghuaihai plain.The results showed that,with the increment of soil water content,the cotton plant height,fruit
number(buds and bolls and flowers) of nutrition branches,plant leaf area,fruit branch number,nutrition branch number,and the ratio of leaf area/fruit all were improved,but the tilt angles of nutrition branches and fruit branches,and the fruit number per unit leaf area decreased significantly.When the soil relative water content was lower than 70%(the water-holding capacity of experiment field was 24%),the ratio of fruit branch leaf area/plant total leaf area(FBLA/PTLA) decreased,but the ratio of stem leaf area/plant total leaf area(SLA/PTLA) increased.When the soil relative water content was higher than 70%,the ratios of both FBLA/PTLA and SLA/PTLA decreased,but the ratio of nutrition branch leaf area/plant total leaf area(NBLA/PTLA) increased.During the earlier stage of flowers-bolls,under the treatment of 70% soil relative water content,the ratio of seed-cotton dry matter weight/stem and branch and leaf dry matter weight,boll and bud number were the biggest,which came up to 1.31,9.3/plant and 53.7/plant respectively.The studies confirmed that,in the cotton area of Huanghuaihai plain,the lower limitation of optimal soil water content of cotton field from bud stage to silking stage was 70%.In this way,the cotton morphological development was better,the coordination progress of source-sink relationship was improved,and the cotton yield was increased too.