Year Effects on Partitioning of Dry Matter into Cotton Boll Components1

Abstract

The distribution of dry weight in cotton boll walls, seeds, and fibers was investigated through the boll developmental period for one flowering date each year in 1979 and 1980. Previous experiments on patterns of fiber development encountered large environmental variation, so this experiment with four diverse cottons was undertaken to measure the effect of years on dry weight distribution into boll components. There was a large difference between years in temperature and moisture, with 1980 being hot and dry. Associated with differences in weather between the years was a large difference in dry weight distribution and boll development. In 1980, cotton matured in 88% of the time, individual boll dry weight was reduced 25%, boll wall dry weight per boll was reduced 17%, seed dry weight per boll was reduced 15%, and fiber dry weight per boll was reduced 41% compared to 1979. In addition, bolls developed in 1980 had fewer but larger seeds and fewer but larger fibers than in 1979. Total lint yield was reduced only 7% in 1980 vs. 1979, so more bolls were produced in 1980. At the individual boll level, the differences between years had the greatest effect on fiber dry weight. The effect on fiber dry weight per boll demonstrated the vulnerability of fiber development to environmental variation.