Abscission of Cotton Floral Buds and Bolls as Influenced by Factors Affecting Photosynthesis and Respiration1

Abstract

The effects of some environmental factors on abscission (shedding) of young cotton (Gossypium hirsutum L.) fruits were investigated because excessive shedding is sometimes a problem in cotton production. Increasing the concentration of CO2 in the atmosphere from 350 to 1,000 ppm decreased shedding, increased the glucose and fructose contents of leaves, and lowered the average node number of the first bolls. Increasing the daily photoperiod from 8 to about 14 hours had similar effects. Conversely, shedding was increased by warm nights (30 C) and by low light intensity.These results indicate that factors that decrease photosynthesis or increase respiration may delay fruiting and decrease retention of floral buds (squares) and bolls. Low light intensity could become critical with high plant populations (more than 100,000 plants/ha), cloudy weather, rank growth, or a combination of the above conditions.