IRRIGATION MANAGEMENT ON IRRIGATED RICE CROP AND ON WATER USE EFFICIENCY IN TROPICAL FLOODPLAINS

Abstract

Appropriate management of irrigation water is among the techniques necessary to achieve high productive potential in irrigated agricultural systems. The objective of this study was to determine the influence of irrigation management on the agronomic performance of irrigated rice cultivars and on the water use efficiency in tropical floodplains. The study consisted of three experiments, one carried out in the Unitins Experimental Field, in Formoso do Araguaia, TO, in a Plinthosol, and two in the Palmital Farm of Embrapa Rice and Beans, in the municipality of Goianira, GO, in a Gleysol. Four water managements were evaluated: Continuous flooding - CI (conventional method, with continuous water depth throughout the cycle); Intermittent irrigation throughout the cycle - II; Intermittent irrigation until flowering, after continuous - IIF and Saturated soil - SS (soil maintained above field capacity, but without water depth), and the cultivars BRS Pampeira, BRS Catiana, BRS A702 CL and IRGA 424. The experimental design used was completely randomized, with five replications, in the split plot scheme consisting of the four water managements, and the subplots by the cultivars. Saturated soil provides an average grain yield of irrigated rice cultivars similar or higher by up to 16% to traditional water management with continuous flooding, with a reduction of up to 82% in the volume of water applied, which results in greater water use efficiency. Saturated soil and intermittent irrigation are strategies to rationalize the use of water resources in rice growing.