Analysis of cotton yield stability across population densities

Final lint yield in cotton (Gossypium hirsutum L.) is relatively stable acr oss a wide range of population densities. This study was conducted to deter mine (i) which components of final lint yield impart this yield stability a cross plant populations and (ii) how yield distribution is influenced by po pulation density. Studies were conducted in 1997 and 1998 on a Tifton loamy sand (Fine-loamy, kaolinitic, thermic Plinthic Kandiudults). Cotton was pl anted in each study on 91-cm row widths at seeding rates ranging from 3.5 t o 25.1 seeds m(-2). At harvest, each plot was hand picked and boil numbers and weights were recorded at each monopodial branch and sympodial branch fr uiting position. Lower population densities led to plants with more mainste m nodes and monopodial branches with increased fruit retention, resulting i n greater fruit production per plant. Boil size was inversely related to po pulation density. Mean net assimilation rate from first flower to peak bloo m also was related inversely to population density. The mainstem node of pe ak boil set increased with population density. Fruit production on a ground area basis was greater in the first sympodial position as population densi ty increased, while fruit production on a ground area basis in third positi ons and monopodial branches was greater as population density decreased. Ac cumulative seedcotton from sympodial branches also increased with populatio n density. Total fruit number and seedcotton yield per area were not influe nced by population density in these studies. Yield stability across populat ion densities was achieved through manipulation of boil occurrence and weig ht.