Integrated Nitrogen Management on Weed Growth and Yield Performance of Transplant Aman Rice

Abstract

Rice requires nitrogen in larger quantities than any other nutrient, and it is the most critical limiting factor that influences grain yield. But inappropriate sources and management of nitrogen is considered to be the most critical one among the various reasons of low rice productivity. In order to address the problem, an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, during June to October 2020 to determine the effect of integrated nitrogen management (INM) on weed growth and yield of transplant aman rice. The experiment comprised five aman rice varieties, viz. Binadhan-7 (V1), BRRI dhan56 (V2), BRRI dhan66 (V3), BRRI dhan71 (V4) and BRRI dhan75 (V5) and four nitrogen management approaches: control (no nitrogen) (N0), 100% of recommended dose (RD) of nitrogenous fertilizer as prilled urea (150 kg ha-1) (N1), 2.5 t ha-1 poultry manure + 75% of RD of nitrogenous fertilizer as prilled urea (112.5 kg ha-1) (N2) and application of USG (1.8 g per 4 hills) (N3). Results reveal that maximum weed density and dry weight were found in BRRI dhan56 whereas minimum ones were observed in BRRI dhan66. In case of INM, application of 100% of RD of nitrogenous fertilizer as prilled urea showed maximum weed density and dry weight but minimum ones were found with application of USG. In combine, weed density and dry weight were found highest in BRRI dhan56 with 100% of RD of urea and the lowest weed density was found in BRRI dhan66 with no nitrogen treatment at 20 DAT and in BRRI dhan66 with application of USG at 35 DAT and lowest weed dry weight was obtained from Binadhan-7 with application of USG (1.8 g per 4 hills) at 20 and 35 DAT. Variety Binadhan-7 showed superior performance in terms of yield and yield attributes. Application of USG showed the highest number of grains panicle-1 and grain yield. Interaction of Binadhan-7 with application of USG produced highest number of grains panicle-1 (116.60), highest grain yield (5.21 t ha-1), biological yield (10.94 t ha-1), harvest index (47.65%) and highest BCR (1.57). So, results indicated that Binadhan-7 with application of USG (1.8 g per 4 hills) might be recommended for obtaining highest grain yield with higher nitrogen use efficiency, highest BCR as well as to control weed more effectively in aman season.