Função de resposta do algodoeiro à água no oeste baiano.

Abstract

Cotton cultivation is expanding in the western part of Bahia and needs technical scientific research base to improve the orientation to the producers. Seeking to contribute for the development in the area, this work was accomplished at Santa Cruz Farm, located in Barreiras-BA (coordinates 12º03'09” of latitude South, 44º57'46,6” of longitude West of the meridian of Greenwich) during March to September of 2004. They were evaluated the physical and financial returns of the herbaceous cotton (Gossypium hirsutum L. r.) cultivar Acala 90, as function of water depth were evaluated, under central pivot, in a Yellow Latosol (loamy sand). The treatments were 0.75, 0.90, 1.05 and 1.20 of the evapotranspiration of the crop (ETc) (L1 to L4), besides the handling of water of the farm (Lp). The production function obtained for the cotton had the maximum point at water depth of 671 mm and production of 5,522.8 kg.ha-1 of cotton, but the economical depth (L*) was found to be 656.5 mm (for 0,3 in the relationship: R$.mm-1.ha-1/R$.kg-1 of cotton in pit); Z obtained with L* was 352.34 kg.ha-1 superior to that obtained under the water management of the farm, resulting in an additional net return of 25.82%.