Effect of irrigation and nitrogen fertilization on the agronomic traits and yield of irrigated rice

ABSTRACT Water and nitrogen management is essential to achieve high yield potential in irrigated agricultural systems. This study aimed to evaluate the influence of flood timing and nitrogen management on the agronomic performance of irrigated rice in tropical lowland. Two experiments were conducted in a Dystrophic Haplic Gleysol during the 2007/08 and 2008/09 crop years. The experiments were carried out using the cultivars BRS Jaçanã and Epagri 109. Flood timing combined with timing of topdressing 90 kg ha -1 N was evaluated at 15, 30, 45 and 60 days after emergence. The experiment was arranged in a split plot completely randomized design, flood timing in the plots and N application in the subplots, with six replications. Late flooding as well as late nitrogen application resulted in reduction of phytobiomass, grain quality and yield of irrigated rice. Flooding is recommended at the beginning of tillering for cultivar that shows higher initial growth, while for slower growth cultivar, ponding water can be established until mid-tillering. Early flooding increases sheath blight severity in rice stems. For improved quality and productive potential of irrigated rice, early flooding period and efficient sheath blight control is necessary.