Response of Applied Phosphorus Fertilizer Rate and Plant Spacing for Potato (Solanum tuberosum L.) Production on Nitisols in Central Highland of Ethiopia

Abstract

The use of low phosphorus fertilize rate as well as inappropriate plant spacing are one of the main factors constraining potato production in Ethiopia. Therefore, a field experiment was conducted during the 2015 and 2016 main growing season in Welmera and Ada'a Berga district in the central highland of Ethiopia. The experiment was aimed at determining the effect of phosphorus fertilizer rates and plant spacing on yield and yield components of potato. The treatments consisted of five phosphorus fertilizer rate and four levels of plant spacing (65 cm x 30 cm, 75 cm x 30 cm, 85 cm x 30 cm and 95 cm x 30 cm). The experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times. Analysis of the results revealed that phosphorus fertilizer and plant spacing significantly affected leaf area index, marketable tuber number, total tuber numbers, total yields, specific gravity and tuber dry matter. However, days to follower and days to maturity significantly affected by phosphorus fertilizer but did not affect by plant spacing. Increasing or widening plant spacing significantly reduced total as well as unmarketable tuber yields whereas decreasing or narrowing it significantly increased this yield parameter. On the other hand, increasing plant spacing significantly increased marketable tuber yields. In conclusion, the phosphorus fertilizer and plant spacing produced the highest tuber yields (ton ha-1) as well as marketable tuber yield in response to planting at phosphorus fertilizer in the form of P2O5 115kg ha-1 and spacing of 85 cm between rows and 30 cm between plants for Belete variety was advisably.