A field experiment was conducted during 2018 cropping season to evaluate the response of sulfur level and variety on yield, yield component and quality of onion at Shewa Robit, North Shewa, Ethiopia. The experiment consisted of three onion varieties (Bombay Red, Red coach F1 and Red king F1) with five sulfur (S) level (0, 7, 25, 43 and 61kg S /ha). The treatments were laid out in a factorial arrangement with three replications using randomized complete block design (RCBD). Application of 43kg S/ha recorded the highest average weight of bulb, yield (t/ha) and pyruvic acid content which was increased by 42, 47 and 104 % over the control. Application of 43kg S/ha also significantly increased the uptake of S, N, and P by 76, 175 and 226%, respectively compared to the control. Application of 43kg S/ha with Bombay Red, Red coach F1 and Red king F1 varieties increased the mean weight of bulb, yield (t/ha) and pyruvic acid content by 32, 52 and 41%; 36, 43 and 62%; and 100, 85, 135%, respectively over the control. Application of 43kg S/ha with R. coach F1 also recorded the highest percentage of marketable bulb and nutrient uptake which resulted in the lowest cost of production and higher benefits on both yield and quality of onion while Bombay Red was recorded the lowest value. Application of 43kg S /ha with R. coach F1 variety can be recommended for onion producers around the district to maintain yield and quality of onion.

Keywords: Onion, sulfur rate, marketable yield, quality, pyruvic acid.