Effect of Nitrogen Sources for Spikelet Sterility and Yield of Boro Rice Varieties

Rice yield can be increased in many ways such as developing new high yielding varieties or adopting proper agronomic management to the existing varieties. Proper fertilization is an important management practice to increase rice yield. Proper fertilization can markedly increase the yield and improve the quality of rice [1]. Nitrogenous fertilizer has immense effect on rice yield throughout the positive influence on the production of effective tillers [2]. Nitrogen not only enhances the yield of rice but also reduces the spikelet sterility. Nitrogen is required in adequate amount at early, at mid tillering and panicle initiation stage for better grain development [3,4]. The soil nitrogen status of Bangladesh is also very low due to warm climate as well as extensive cultivation practices without addition of manures. The nitrogen efficiency, especially of urea fertilizer, is very low in rice cultivation. Nitrogen losses ranged from 2.82-5.07% in rice field [5]. The use of USG and Mixed fertilizer has often been advocated to minimize nitrogen losses because organic manures act as a great source of plant nutrients, especially of N, P, K and S, and also prevents leaching loss of the nutrients. USG @ 120 kg N ha-1 was the best in producing the yield and yield attributes of rice [5]. Prilled urea also plays a vital role in improving physical, chemical and biological properties of the soil and ultimately enhances crop production. Application of heavy nitrogen increases tillering as well as spikelet number per plant thus reduces the number of engorged pollen grains per anther and leading into increased spikelet sterility [6]. This study was undertaken to evaluate the response of different varieties with the application of different nitrogen sources for obtaining optimum yield by reducing spikelet sterility of boro rice.