FFECT OF DRIP IRRIGATION LEVELS AND NPSB FERTILIZER RATES ON YIELD AND YIELD COMPONENTS OF ONION (Allium cepa L.) AT DEMBIA DISTRICT, NORTH GONDAR, ETHIOPIA

Onion (Allium cepa L.) is one of the major horticultural crops grown in Dembiya district, Ethiopia. However, due to lack of research recommendations on agronomic practices, growers are not using optimum irrigation level and NPSB blended fertilizer rate. The main objects of this study to check the effects of drip irrigation levels and NPSB blended fertilizer rate. The treatment consist of three irrigation levels (100%, 80% and 60% ETc) and five NPSB blended fertilizer rate (0, 50, 100, 150 and 200 Kg ha- 1 ) arranged in split plot design with three replications. The result revealed that all data except bulb weight, dry matter content and harvest index were significantly affected by irrigation levels and fertilizers rates. The maximum marketable yield (28.24 t/ha) was obtained under 100 % ETc and 200 kg ha-1 of NPSB blended fertilizer rate with165 kg ha -1 application of Urea. With water saving of 20%, a yield reduction of 12.74% was recorded from treatments receiving 80% ETc and 200 kg ha-1 NPSB and 165 kg ha-1 of Urea application. The study also revealed that yield response factor ranged from 1.87 to 0.68 and the lowest (0.68) Ky was recorded from 80 % ETc and 200 kg ha- 1 NPSB application. Whereas, the highest yield response factor was recorded from 60 % ETc and control plot. Better water use efficiency was recorded in plot receiving 80 % ETc and 200 kg ha-1 NPSB fertilizer rate. The present study suggests that, in water scarce area, farmers are advised to adopt 80% of irrigation level and 200 kg ha-1 NPSB blended with Combined 165 kg ha-1 of Urea. However, if water is not a limiting factor in the study area, farmers are advised to apply full irrigation water application under 200 kg ha-1 NPSB and 165 kg ha-1 of Urea application.