Effect of Potassium Fertilizer Rate on Growth, Yield and Yield Related Parameters of ‘Irish Potato (Solanum Tuberosum L.) at Bale Highlands

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Potato (Solanum Tuberosum L.) is one of the most important food security and cash crops in Ethiopia. However, its productivity is generally low. The low yields of the crop could be attributed to a number of factors among which low soil fertility is an important constraint and there is little information on the type and rates of fertilizers to be applied for optimum production of the crop under different agro-ecological conditions of the country. Therefore, an on-farm experiment was conducted at Dinsho and Sinja, south-eastern Ethiopia, to assess the effect of potassium fertilizer rate on yield and yield related parameters of ‘Irish potato (Solanum Tuberosum L.) at Bale Highlands. Factorial combinations of two potato varieties (Ararsa and Moti) and five rates of potassium fertilizer (0, 25, 50, 75 and 100 kg K ha-1) were laid out in a randomized complete block design (RCBD) with three replications. Analysis of variance showed that the main effects of potassium fertilizer significantly influenced (days to 50% flowering, plant height, number of tuber per plant, number of marketable tuber per plot, marketable tuber yield and total tuber yield) had highly significant (P < 0.01) while non-significant for days to 90% maturity, number of unmarketable tuber per plant and unmarketable tuber yield. An improved varieties Ararsa and Moti were produce the highest marketable tuber yields of 21.23 t ha-1 and 19.50 t ha-1 respectively, with application of 100 kg KCl ha-1 and with the application of recommended rate of NP fertilizer while the lowest marketable yields of 15.01 t ha-1 and 14.96 t ha-1 from Ararsa and Moti Varieties, respectively, were obtained from unfertilized KCl fertilizers treatment, respectively. The economic analysis revealed that the highest net return of (187170 and 169620 ETB ha-1) with marginal rate of return (4764.29 and 1185.71%) were recorded for varieties of Ararsa and Moti respectively, at 100 kg KCl ha-1. Therefore, it can tentatively be concluded that application of 100kg KCl ha-1 and recommended rate of NP fertilizer best to optimum tuber production and economic returns for potato at Bale Highlands.