Manejo da irrigação na cultura do arroz irrigado e na eficiência do uso da água em várzeas tropicais

Abstract

Appropriate irrigation water management 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 the water use efficiency in tropical floodplains. The study consisted of three experiments: The first was carried out at the Experimental Field of Unitins in Formoso do Araguaia, TO, in a Plinthosol and the second and third at the Palmital Farm of Embrapa Rice and Beans, in the municipality of Goianira, GO, in a Gleysol. Four water managements were evaluated: a) Continuous flooding - CI (conventional method, with continuous water depth throughout the cycle); b) Intermittent irrigation throughout the cycle - II; c) Intermittent irrigation until flowering, after continuous – IIF; and d) 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. Results showed that saturated soil provides an average grain yield similar or higher of up to 16% of irrigated rice cultivars in relation to traditional water management with continuous flooding, reducing up to 82% in the volume of water applied, which results in greater water use efficiency. Thus, saturated soil and intermittent irrigation are strategies to rationalize water resources in rice growing.