Yield, Yield Component and Fiber Property Variation of Cotton (Gossypium hirsutum L.) Within and Among Environments1

We evaluated the performance of four cotton (Gossypium hirsutum L.) cultivars when grown under four environments at Stoneville, Mississippi. Each variety was harvested by hand at approximately weekly intervals, averaging nine harvests per environment. We obtained estimates of yield, seven yield components, and seven fiber properties for each harvest. Generally for the first two harvest weeks cotton bolls opened at a relatively slow rate, approximately 10 kg/ha per day. This was usually followed by 4 weeks of a greater rate of opening, approximately 24 kg/ha per day. After this period the rate of opening decreased substantially to approximately 7 kg/ha per day. The most important cultivar ✕ harvest interactions were for yield, number of bolls, and rate of boll opening. These interactions were related most to the distribution of yield within environments. Lint percentage was lowest for the early harvest, whereas boll size and seed index values became smaller as the season advanced. Lint index was highest for the middle harvests. There was no consistent seasonal trend in number of seed per boll. Cultivars were the most important source of variability for fiber properties. Yarn strength, 50% and 2.5% span length, length uniformity, fiber strength, and Micronaire were usually lower for the last two harvest dates. Lower quality fiber and low yield potential in the last two harvests suggest that early season production would be advantageous to the cotton industry. The implications of this study pertaining to sampling for yield, yield components, and fiber properties are discussed.