Abstract:
Potato is an important food and cash crop in Eastern Hararghe Zone. However, the productivity of the crop is low at national as well as district levels; due to various limiting factors such as low soil fertility and lack of improved varieties. Therefore a field experiment was conducted with the objectives of determining the effect of blended (NPSB) fertilizer rates on yield and quality component of potato varieties in Goro-Gutu district under rain fed condition during the 2021 cropping season. The treatments consisted of four potato varieties, namely, two improved varieties (Bubu and Gudene) and two local farmers varieties (Mogor and Dararaa-dima) and five rates of NPSB (0, 100, 150, 200 and 250 kg NPSB ha-1) fertilizer rates. The experiment was laid out as a Randomized Complete Block (RCBD) design in a 5 x 4 factorial arrangement with three replications. Analysis of variance revealed blended NPSB fertilizer and variety had significant effects on crop phenology, growth, tuber yield and yield components, as well as tuber quality parameters. On the other hand, tuber yield and yield components were significantly influenced by the interaction of NPSB fertilizer rate and variety’s. Gudene showed earliness in 50% flowering and maturity as compared to the remaining. On the other hand, the higher rates of blended NPSB fertilizer delayed flowering and maturity compared to the untreated control plots. The tallest plants (66.40 cm) were obtained from Bubu variety followed by variety Gudene with mean plant height of 60.35 cm, while the shortest (53.02 cm) plants were registered from local variety Dararaa-dima. Application of 250 kg ha-1 NPSB fertilizer resulted in 24.5% increment in plant height compared with the shortest plants (53.02 cm) registered from the unfertilized plot. The highest total tuber number per hill (17.44 hill-1) was obtained from the treatment combination of Gudene and application of 200 kg/ha-1 NPSB rate. However, the lowest tuber number per hill (8.73) was recorded from local Dararaa-dima variety from the unfertilized plot. The highest average tuber weight (67.92 g) was recorded from Bubu variety from plots that received 250 kg ha–1 of NPSB fertilizer rate. The highest marketable yield (34.44 t ha–1) and total tuber yield (37.47 t ha-1) were recorded from Gudene variety at 200 kg NPSB ha–1 while, the lowest value was obtained from unfertilized plots of Dararaa-dima, the local variety. On the other hand, the highest unmarketable tuber yield of (11.33 t ha-1) was obtained from of Dararaa-dima that did not receive fertilizer. Percentage of medium and large tuber size were increased with increased levels of NPSB fertilizer rates. Moreover, the highest net benefit of (206270) Birr ha-1 with acceptable (10385 %) marginal rate of return were obtained from growing of Gudene variety with the application of 200 kg ha-1 blended NPSB fertilizer
