Response of Potato (Solanum tuberosum L.) to Nitrogen Fertilizer Application at Angecha, Southern Ethiopia

Nitrogen is one of the most limiting essential nutrients for plant growth and development. Its fertilizations play an important role in the balance between vegetative and reproductive growth of potato. In this context, field experiment was conducted during 2015/16 cropping season at Angacha testing site of Areka Agricultural Research Center to determine the optimum N fertilizer rate for potato production. Treatments consisted of two potato varieties: Gudane (CIP-386423.13) and Belete (CIP393371.58) with seven N levels (0, 23, 46, 69, 92, 115 and 138 kg ha-1 N) were combined in factorial and laid out in a randomized complete block design (RCBD) with four replications. Analysis of variance revealed that N rates had significant effect on days to flowering and physiological maturity where both parameters were prolonged with increasing N rates. Significant differences were detected due to effect of varieties by N rates interactions on days to flowering and maturity where for both varieties days to flowering and physiological maturity delayed with increasing N rates. Regarding variety by N rate interactions, the highest plant height was observed for Gudane at N rate of 138 kg ha-1 and the lowest plant height was recorded for Belete from non N application plots. Varieties by N rates interactions resulted in significant differences on marketable tuber yield with the highest marketable tuber yield was observed for Belete at N rate of 69 kg ha-1. In line with this, varieties significantly differed for total tuber yield where variety Belete gave higher total tuber yield than that of variety Gudane. This result revealed that both varieties gave better yield that N rate of 69 kg/ha with superior performance of variety Belete. Based on this finding, application of 69kg N ha-1 for both cultivars could be recommended for production at Angecha and similar agro-ecologies. Keywords: Varieties, Nitrogen fertilizer, Tuber yield, Tuber number, Economic feasibilit