Effect of Application Rate of Urea on the Growth, Bulb Yield and Quality of Onion (Allium Cepa L.) Grown under Semiarid Conditions of North Jordan

Field experiment was conducted to assess the effect urea fertilizer rates on growth and yield of onion (Allium cepa.var Giza 20) grown under semi-arid conditions of north Jordan, during 2011–2013. Transplants of uniform size were used. The treatments consisted four levels of urea(0, 200,400 and 600 kg ha -1) were applied as broadcast. The experimental design used was randomized complete block design. A significant increase in bulb weight per plant, number of leaves, plant height,neck diameter, leaves weight,bulb diameter,bulb lengthand plant weight with urea application at all rate was recorded and the highest bulb weight was registered for 600 kg ha -1. Agronomic urea efficiencyas well as vitamin c declined with increase in rates of urea application, while ash percentage increased with increase in rates of urea application. These results suggest that broadcast application of urea significantly influenced the growth, yield and vitamin c of onion.