RESPONSE OF SHALLOT (Allium cepa var. Ascalonicum Backer) VARIETY TO NPS AND POTASSIUM FERTILIZER RATES FOR SEED YIELD AND QUALITY AT HARAMAYA AND DIRE DAWA, EASTERN ETHIOPIA

Shallot (Allium cepa var. ascalonicum Backer) is one of the most important and widely used vegetable crops propagated vegetatively in Ethiopia. The yield of bulbs and seed are often constrained with low and imbalanced nutrient supply in the soil mainly nitrogen, phosphorus, sulfur and potassium. Therefore, a field experiment was conducted at Haramaya and Dire Dawa research stations of Haramaya University to assess the effect of NPS and potash fertilizers on seed yield and quality of Improved Huruta shallot variety during 2018/19 under irrigation conditions. The treatments consisted of four rates of NPS (0, 50, 100, and 150 kg ha-1) and four rates of potassium (MOP) fertilizers (0, 50, 100, and 150 kg ha-1). The experiment was laid out in a randomized complete block design in a factorial arrangement with three replications. The seed quality test was conducted in the Seed Science and Technology laboratory of Haramaya University in a complete randomized design in a factorial arrangement with four replications.The results of the analysis of variance for each location and over locations revealed that phenological, growth, umbel characteristics, seed yield components, seed yield, seed physical and physiological quality parameters of shallot variety were significantly influenced either by one or both NPS and MOP and/or the interaction of the two fertilizers. The location had a significant effect on phenological, growth, umbel, seed yield components, seed yield, seed quality parameters except for the proportion of abnormal seedlings, seedling shoot length and seedling vigor index II. Interaction of location x NPS x MOP had a significant effect on days to bolting and maturity, seed yield and yield components except for the number of flower stalks per plant, number of umbels per plant, and seed quality parameters except for seedling shoot and root length. The highest seed yield of 500.2 kg ha-1 was produced with the highest germination of seeds (91.5%) at Haramaya with the application of 150 NPS x 150 MOP kg ha-1 fertilizers. The variety produced higher seed yield with a higher percentage of germination at Haramaya than Dire Dawa with the application of similar rates of fertilizers. The research results showed that the application of NPS and MOP fertilizers at higher rates particularly 150 NPS x 150 MOP kg ha-1 at Haramaya produced higher seed yield with the required seed quality. However, the varied response of shallot variety to varied rates of NPS, MOP and combination of the two fertilizers at two locations suggested the importance of conducting a further study over many locations to identify the rates of NPS and MOP fertilizers to produce the highest seed yield and seed quality from Improved Huruta shallot variety