Response of Potato ( Solanum tuberosum L.) Yield and Yield Components to Nitrogen Fertilizer and Planting Density at Haramaya, Eastern Ethiopia

Abstract

To investigate the effect of nitrogen fertilizer and planting density on yield and yield components of potato crop (Bubu variety), a field experiment was carried out in Haramaya, Eastern Ethiopia during the rainy season of 2012. The experiment was a 4 x 5 factorial combination and a randomized complete block design with 3 replicates. Treatments included quantity of nitrogen fertilizer (0, 110, 165 and 220 kg N/ha) and planting density (4.17 plant m-2 (80 cm x 30 cm), 4.44 plant m-2 (75 cm x 30 cm), 5.56 plant m-2 (60 cm x 30 cm), 6.67 plant m-2 (60 cm x 25 cm) and 8 plant m-2 (50 cm x 25 cm)). Increasing nitrogen level up to110 kg N/ha lead to more tuber yield, highest stem number, plant height, total dry biomass, total tuber number, large-sized tuber yield (59.01%) and marketable tuber yield. The highest foliar N concentration was recorded at 165 kg N/ha. Increasing planting density resulted in higher tuber yield; total tuber number, total dry biomass yield (%), marketable tuber yield and small-sized tuber yield (16.92%). Highest foliar N concentration was found at the lower planting densities of 4.17 and 4.44 plant m-2. Yield of tuber per hectare was significantly and positively correlated with leaf area index, total tuber number, days to physiological maturity and total dry biomass yield. In conclusion, results of the experiment revealed that 110 kg N/ha and planting density of 6.67 plant m-2 resulted in optimum total (35.50 and 35.66 t/ha, respectively) and marketable tuber yields of the Bubu variety in Haramaya, Eastern Ethiopia during the rainy season.