Effect Of Planting Density And Nps Fertilizer Rate On Growth, Yield And Yield Componenets Of Potato (Solanum Tubersum L.) At Jimma, South West Ethiopia

Potato (Solanum tuberosum L.) is an important leading tuber crop for food and nutrition security as well as cash crop for smallholder farmers in Ethiopia. However, the yield of the crop is low at national as well as regional level which is constrained mainly by in appropriate planting density and low soil fertility. There is a need to optimize planting density and fertilizer to enhance crop growth and tuber yield. Therefore, a field experiment was conducted to investigate the effect of planting density and NPS fertilizer on growth, yield and yield components of potato at Jimma, south- western Ethiopia during the rainy season of 2019/2020. Four levels of intra-row spacing (20, 25, 30 and 35 cm) and four levels of NPS fertilizer (0, 75, 150 and 225kg ha-1 NPS) were arranged in a randomized complete block design with 3 replicates as a 4 x 4 factorial combination. Results of the experiment indicated that the main effects of intra-row spacing and NPS fertilizer as well as the interaction effects highly significantly affected days to 50% flowering, plant height, main stem number, days to 75% physiological maturity, total tuber number per hill, weight of tubers, marketable tuber number per hill, unmarketable tuber number per hill, total tuber yield (t ha-1), marketable tuber yield (t ha-1) and unmarketable tuber yield (t ha-1).Total tuber yield increased with the increased plant population and NPS fertilizer. The highest total tuber yield (40.36 ton ha-1) was obtained from the treatment combination of 20 cm intra-row spacing and 225kg ha-1 NPS. On the other hand, the lowest total tuber yield (13.4 tons ha-1) was recorded for the treatment combination of 35cm intra-row spacing and zero NPS fertilizer application. Based on the partial budget analysis, the treatment combination of 30 intra-row spacing and 225kg ha+ NPS fertilizer gave the maximum net return of Birr 404255.3 ha-1.