Growth and Development of Fiber and Seed in Upland Cotton1

Abstract

Three environments and four cultlvars of upland cotton (Gossypium hirsutum L.) were used to evaluate the affect of environment on the growth and development of cotton fiber and seed. The environments were a College Station planting, an early Lubbock planting, and a late Lubbock planting. These environments were quantified by conversion of the daily average temperatures from each environment into heat units. The College Station planting had the most and the late Lubbock planting the least number of available heat units. ‘TM‐I,’ ‘CA 491,’ ‘Acala 1517 Br‐2,’ and ‘Western Stormproof,’ were planted in replicated tests in each environment. Tagged bolls were harvested weekly to give estimates of the rates of fiber elongation and fiber dry‐weight accumulation. After boll maturity, fiber length, fiber elongation periods, fiber/seed, fiber fineness, seed size, and number of seeds/boll, were determined. Linear correlation and regression analyses between heat units and the characters measured after boll maturity were used to evaluate the relationships between environments and cultivars.Environment influenced the rate of fiber elongation and fiber dry weight accumulation. Fiber elongated and accumulated dry weight faster in the College Station environment than in the two Lubbock environments. Correlation and regression coefficients from the simple linear regressions of heat units on the characters measured after boll maturity revealed that all of the cultivars responded to a reduction in the number of available heat units. However, CA 491 and Acala 1517 Br‐2 appeared to be somewhat better adapted to growth and development of fiber and seed in a cooler environment than were TM‐1 and Western Stormproof.