MÉTODOS DE DETERMINAÇÃO E NÍVEIS DE ÁGUA DISPONÍVEL NO SOLO: EFEITO SOBRE A CULTURA DO ALGODOEIRO HERBÁCEO

Abstract

This work evaluated the effect of two methods of determination of soil water (laboratory method and field method) and four levels of soil water availability (20; 40; 60 and 80%) on biomass of the aerial part, crop evapotranspiration, leaf area, plant height and yield in pit of herbaceous cotton plant, cultivar CNPA-7H. The randomized blocks experimental design was used in factorial scheme 2 x 4, with three replications. The determination of available soil water by the field method overcame the results of the studied variables in relation to the laboratory method and it represents more real conditions of the readiness of water for the cotton plant. The leaf area and the evapotranspiration, determined by field method, increased significantly with the levels of available soil water. The management with the available water of 61.61% by laboratory method promoted the maximum leaf area of 1755.4 cm2 and, with 74.4% of levels of available water, the maximum evapotranspiration was of 238 mm. There were earnings of 0.2 g of biomass per unit of levels of available soil water by field method; already by laboratory method the maximum biomass of 17.6 g was reached with the management of levels of available water of 62.9%. The best response for the cotton incomes in pit was given by field method with earnings in the income of 0.26 g for the field method and of 0.11 g for the laboratory method per unit of available soil water.