RESPONSE OF UPLAND RICE VARIETIES TO SEED AND NITROGEN FERTILIZER RATES IN TSELEMTI DISTRICT, NORTHWEST TIGRAY ZONE, NORTHERN ETHIOPIA

Rice is an important crop in Maitsebri area in Tigray region but the productivity of the crop constrained by lack of appropriate agronomic practices including seed rate and also lack of nitrogen fertilizer in the region. Thus, a field experiment was conducted in 2016 main cropping season in Tselemti District, Northwest Tigray Zone to assess the effect of seed and nitrogen fertilizer rates on major upland rice varieties; and to identify economically feasible seed and nitrogen fertilizer rates for rice production. Factorial combinations of two upland rice varieties [Maitsebri -1(NERCA-13)] and Tana (AD-048)], three seed rates (60, 80 and 100 kg ha-1) and four nitrogen levels (0, 46, 69, 92 kg N ha-1) were laid out in randomized complete block design with three replications. Analysis of the results revealed that variety Tana had significantly higher number of total tillers (4.54) and number of effective tillers (4.24) per plant. Thousand kernels weight of rice was significantly affected by the main effect of seed rate where 60 kg ha-1 of seed rate produced the maximum thousand kernels weight (29.40 g). On the other hand, the interaction effects of seed rate and nitrogen rate were significant on lodging percentage, aboveground dry biomass yield and straw yield. Seed rate of 100 kg ha-1 in combination with 92 kg N ha-1 gave the highest lodging percentage (31.33), aboveground dry biomass yield (12500 kg ha-1) and straw yield (8395.83 kg ha-1). Panicle length was significantly affected by the interaction effect of variety and nitrogen where the maximum panicle length (20.98 cm) was recorded from variety Maitsebri-1 at 92 kg N ha-1. The interaction effect of variety, seed rate and nitrogen significantly affected plant height, number of kernels per panicle and grain yield of rice. The highest plant height (107.16 cm) was obtained from Maitsebri-1 variety at 60 kg ha-1 seed rate at 92 kg N ha-1. On the other hand, the highest number of kernels per panicle (76.30) and grain yield (4729.17 kg ha-1)) were recorded from variety Tana at seed rate of 100 kg ha-1 and 92 kg N ha-1. However, the economically feasible grain yield (4375 kg ha-1) was obtained from Miatsebri-1 variety at 100 kg ha-1of seed rate with 92 kg N ha-1 which gave economic benefit of 32095.22 Birr ha-1 with the marginal rate of return 1695.29 %. While, 46 kg N ha-1 and variety Tana had significantly higher nitrogen agronomic efficiency (57.48 and 53.6 kg kg-1) respectively. Hence, based on one-year experimentation, Maitsebri-1 variety at seeding rate of 100 kg ha-1 with 92 kg ha-1of nitrogen rate can be tentatively recommended for Tselemti areas.