EFFICACY OF DIFFERENT LEVELS OF NITROGEN AND METHODS OF WEEDING ON THE GROWTH AND YIELD OF HYBRID BORO RICE

Abstract

The experiment was conducted at the Agronomy Field of Sher-e-Bangla Agricultural University, Dhaka during the period from December, 2011 to May, 2012 to study the efficacy of different levels of nitrogen (N) and methods of weeding on the growth and yield of hybrid boro rice (Heera 4). The treatments consisted of four N levels viz., No = 0 kg N ha-1, N1 = Urea super granules (2.7 g) @ 75 kg N ha-1, N2 = 140 kg N ha-1, N3 = 180 kg N ha-1 and five different weed control methods viz., W0 =No weeding (Control), W1= One weeding (30 days after transplanting), W2= Two weeding (30 DAT & 50 DAT), W3= Sunrice 50WG at recommended dose (100 g ha-1), W4=Topstar 80WG at the recommended dose (80g ha-1). The experiment was laid out in a split-plot design with three replications having nitrogen doses in the main plots, weed control in the sub plots. Necessary intercultural operations were done as and when necessary. Nitrogen and weed control had significant influence on growth, yield and yield components of hybrid rice. The tallest plant was observed with urea super granules (USG). The maximum tillers number hill-1(16.8), LAI (6.21), total dry matter (90.33g hill-1), effective tillers hill-1(13.40), the longest panicle (24.17cm) and number of filled grains panicle-1(176.50) were obtained with USG. The maximum 1000-grain weight (29.20g) was obtained from USG treatment. The highest grain yield (8.10 t ha-1) was obtained from Urea super granules. The lowest grain yield (5.44 t ha-1) was observed in control. The highest straw yield and biological yield were observed in USG. The highest plant height (95.39cm), number of tillers hill-1(15.22), LAI (6.47), CGR (3.30 g hill-1 day-1), effective tiller (11.61), panicle length (24.29cm) and filled grain panicle-1 (173.00) were found in Sunrice 150WG. The highest total grain panicle-1(185.48), 1000 grain weight (30.36g) were recorded from Sunrice 150WG. The highest yield (7.97 t ha-1) was recorded from Sunrice 150WG and the lowest yield (5.79 t ha-1) was obtained from no weeding treatment. The highest straw yield (10.68 t ha-1) and biological yield (19.13 t ha-1) were recorded from Sunrice 150WG. Significant highest (9.48 t ha-1) grain yield was found from the combination of USG with Sunrice 150 WG and the lowest (4.66 t ha-1) from combination of no nitrogen and no weeding.