Development of Cotton Fruit I. Accumulation and Distribution of Dry Matter1

Abstract

AbstractInvestigations of cotton (Gossypium hirsutum L.) boll growth have usually been limited to studies of fiber formation. To relate cottonseed development to previous research on fiber, a general study of cotton boll development was made. Cotton was planted in a field of Bosket fine sandy loam, a fine‐loamy, mixed, thermic Mollic Hapludalf. Dry matter accumulation by cotton fruit was measured to identify ontogenetic relationships among the bur (carpel walls), the seed, and the fiber.Measurements of boll growth were made between 10 days after flowering and maturity (boll cracking stage). Dry weight of the bur increased rapidly and reached final weight by the end of the 3rd week of development. At this time, dry weights of seed and fiber were only about 40% of their final values. Both the seed and the fiber accumulated dry matter for about 6 weeks, but the fiber accumulated dry matter at a slightly faster rate than did the seed. At maturity, the bur accounted for about 21%, the seed for about 38%, and the fiber for about 41% of the boll dry matter.Although bolls had reached final dry weight by the end of the 6th week of development, they did not open until about 2 weeks later. Both the number of fruit competing for photosynthate and the environmental conditions prevailing during development were found to affect the accumulation of dry matter by the boll components.