Response of potato (Solanum tuberosum L.) varieties to blended NPSB fertilizer rates on tuber yield and quality parameters in Gummer district, Southern Ethiopia

Abstract

Potato is an important food security and cash crop in Southern Ethiopia, including Gurage Zone. However, the productivity of the crop in the zone is far below its potential due to an array of factors. For instance, inappropriate selection of varieties and lacking information regarding the actual rate of the newly recommended blended NPSB fertilizer in the potato-producing areas, including Gummer district. Cognizant of this, the present experiment was initiated and conducted in Gummer district under supplementary irrigation, during the 2021 Belg season, with the objective of assessing the response of different potato varieties to blended NPSB fertilizer rates. The experiment was laid out in randomized complete block design (RCBD) with the factorial arrangement and having three replications. There were 12 treatment combinations, comprising three potato varieties (namely; Belete, Gudanie and a local check, Askot) and four blended NPSB fertilizer rates (0, 119, 238 and 357 kg NPSB ha-1). The analysis of variance showed that the two main factors (blended NPSB fertilizer rates and potato varieties) had a statistically significant effect on all tested parameters except the effect of the blended NPSB fertilizer rates on days to 50% emergence. The interaction of the two factors had also showed a statistically significant effect on days to 90% maturity, plant height, main stem number per plant, total tuber number/hill, tuber yield per hill, large-sized tuber yield, marketable and total tuber yields (t ha-1) and tuber dry matter content. Days to 90% maturity were delayed with increased rates of blended NPSB fertilizer for all tested varieties. The highest mean plant height (69.54 cm) and number of main stems per hill (8.38) were obtained at 357 kg ha-1 NPSB with Belete variety. The highest marketable tuber yield (34.40 t ha-1), total tuber yield (35.84 t ha-1) and tuber dry matter content of (26.75%) were obtained from belete variety with the application of 238 kg ha-1 NPSB fertilizer. The results of the economic analysis indicated that the maximum net benefit (180660.7 Birr ha-1) with a 3405.23% marginal rate of return was obtained from Belete variety with the application of 238 kg NPSB ha-1. Hence, the application of 238 kg ha-1 with belete variety can be recommended for optimum potato production with acceptable economic benefit in the study area and similar agroecology. However, since the result is only of one season and location, further research is recommended to be carried out across more seasons and locations