Effects of Water Stress and Plant Density on Cotton (Gossypium hirsutum L.) Cultivars Differing in Maturity and Seed Size: I. Yield Components and Fiber Quality Parameters

To achieve maximum cotton yield, the combination of genotype, environmental conditions and appropriate management practices should be optimized. Field experiments were conducted in the Aegean region of Turkey during 2008 and 2009 to observe the responses of three cotton cultivars differing in maturity and seed size to deficit water stress under different plant densities. Although plant compensation through monopodial bolls and outer position bolls was seen in some cases, at a plant population of 6.2 plants m-2 yields were reduced in both years regardless of irrigation levels. Deficit irrigation inversely affected lint yield, yield components, and fiber quality for all cotton cultivars. It is interesting to note that yield, and yield components in this investigation differed greatly between M-2005 (late-maturing and large-seeded cultivar), and Carmen (late-maturing and smaller-seeded cultivar) and Flash (early-maturing and smaller-seeded). Deficit water stress decreased lint yield and boll number per m-2, lint mass per seed for M-2005 more than Carmen and Flash. Under deficit irrigation, Carmen produced significantly higher yield than Flash in year one, but both cultivars produced similar lint yields in year two. These results suggest that late-maturing and also small-seeded cultivar would be preferable under deficit irrigation, and that optimal plant population was higher under water deficit condition, and that the response to deficit irrigation stress was controlled more by genotype and to a lesser extent by management of plant density.