Growth, Yield and Nitrogen Use Efficiency of New Rice Variety under Variable Nitrogen Rates

Globally, the current important concern is to minimize nitrogen use in crop culture under climate change condition. The experiment was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh during the rainy season of 2014 to assess growth, yield and nitrogen use efficiency of a new rice variety. The new rice variety (BUdhan 1) was treated with six levels of nitrogenous fertilizer in a randomized complete block design replicated three times. The nitrogen levels 0, 20, 40, 60, 80 and 100 kg N ha-1 constituted the treatment variables. Results revealed that growth of the new rice variety favored at higher levels of applied nitrogen although it flattened at 80 and 100 kg N -1. Preanthesis assimilates reserves contributed to sustaining the yield of the variety which indicated that current photosynthesis was insufficient to support the present yield level. The assimilate remobilization varied from 109.21 to 232.93 g·m-2 between the nitrogen levels where the maximum amount of remobilization was observed at 60 kg N -1. The highest grain yield (5.36 t·-1) was found when the variety was fertilized with 60 kg N -1. Application of 60 kg N -1 also showed the highest nitrogen use efficiency (344.50 kg grain/kg N applied) of the variety. We concluded that application of the intermediate level of nitrogen was economical and environment-friendly for the cultivation of new rice variety.

Yield Response of Direct Seeded <i>Aus</i>Rice Varieties under Rainfed Condition

Rainfed Aus rice is a popular conventional rice cultivation technique that through appropriate variety selection can accelerate the benefits of the farmer. On this context, an experiment was carried out at the research field of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur1706 from April to August in 2014 to evaluate yield performance of some Aus rice varieties under rainfed condition. The experiment was laid out in a split plot design with three replications. The experiment consisted of two sets of treatments: water regime as irrigated (irrigation when necessary) and rainfed (dependent on rainfall) in the main plot and 15 varieties into sub-plots. It was revealed that yield and yield contributing characters were significantly influenced by water regime, variety and their interaction. The traits like number of effective tillers and non-effective tillers&middot;hill-1, number of filled grains and unfilled grains panicle-1, panicle length, test weight, grain yield and harvest index were higher in irrigated crops compared to rainfed. Considering the performance of yield, the highest grain yield recorded in BRRI dhan27 (irrigated-2.47 t&middot;ha-1 and rainfed-2.26 t&middot;ha-1) followed by BRRI dhan55 (irrigated-1.95 t&middot;ha-1 and rainfed-1.88 t&middot;ha-1), BRRI dhan48 and BRRI dhan43 under both irrigated and rainfed treatment. BRRI dhan27 ranked the top under both irrigated and rainfed conditions, however the relative yield was maximum in BRRI dhan55 (reduction was only 3.59%) followed by Nerica10. Hence, considering the yield stability and absolute yield performance, BRRI dhan27 may be considered favorably cultivable for Aus season in Bangladesh followed by BRRI dhan55, BRRI dhan48 and BRRI dhan43.