Response of riceto different levels of nitrogen and seed rate at gojeb, southwestern Ethiopia

Abstract

Rice (Oryza sativa L.) is increasingly becoming an important food and cash crop in Ethiopia, especially among small-scale farmers. However, its productivity is challenged due to lack of appropriate agronomic practices and recommendations. Especially, uses of appropriate N fertilizer and seed rates most importantly affect the productivity of rice increasing the cost of production in subsistence farming. Thus, a field experiment was conducted at Gojeb, Gimbo district in kaffa zone, southwestern Ethiopia during 2017 main cropping season with the objective of determining optimum of N level and seed rate application. The experiment was laid out in randomized complete block design in a factorial arrangement replicated three times. The treatments consisted of five nitrogen rates (0, 32, 64, 96 ad 128 kg N ha-1 ) and three seed rates (50,60 and70kg ha-1 ). The analysis of variance revealed that nitrogen rate highly significantly (p<0.01) affected all of parameters studied .Similarly, the interaction between nitrogen level and seed rate also highly significantly (p<0.01) affected total tillers and effective tillers, filled grain per panicle, panicle length and grain yield. Nitrogen concentration, uptake and N-use efficiency parametrs were significantly affected by the interaction effect. Highest number of effective tillers (357.33) persquare meter, numbers of filled grain per panicle (102) and grain yield (4755.2kg/ha) were recorded at 96kNha -1 with 70kg ha -1 of seed. Similarly, highest total and straw N-uptake as well as gran N-content were recorded from 128kgNha-1 and 70kgha-1 from 96 kgNha-1 and70kgha-1 .The highest ANUE(23.63 and 22.37) was recorded from 64and 96kgNha1with 70kgha-1 seed rate.The highest PNUE (138.75 and 135.65) as well as ARE% (93.50 ) was recorded. Therefore, increasing nitrogen rate and seedrate to optimume range 96kgN ha-1 and 70kgha-1 seed rate increased grain yield and yield component of rice. The correlation analysis also indicated that there was positive and highly significant association between grain yield and yield components and N uptake at maturity. The Partial budget analysis showed that highest net benefit and marginal rate of return was obtained at 64kgN ha-1 and70kg ha-1 seed.Hence 64kgN ha-1 and70kg/ha can be recommended in the study area. However, repeating the experiment over years by increasing the N level would help to draw sound recommendation.