Effect of Different Nitrogen and Sulphur Fertilizer Levels on Growth, Yield and Quality of Onion (Allium cepa, L.)

Two field experiments were carried out at a farm in South Ghor area, Jordan, during 2004/2005 and 2005/2006 seasons to study the effect of three levels of nitrogen (100, 150 and 200 kg/ha) and three levels of sulphur (0, 50 and 100 kg/ha) on growth and productivity of onion bulbs Giza 20 cultivar using an experimental design of split plot with three replications for each treatment. The results showed that increasing nitrogen and sulphur application rates significantly enhanced plant height, number of green leaves/plant and weight of plant and bulb at different stages of onion growth. Total yield, marketable yield, culls yield, percentage of marketable, doubles and bolters as well as total soluble solids (TSS%) were also increased with increasing the rates of nitrogen and sulphur up to 200 kg N/ha and 100 kg S/ha in both seasons, respectively; whereas the lowest percentage of pickles yield was recorded with the highest level of nitrogen and sulphur fertilizers. In general, the application of 200 kg N/ha + 100 kg S/ha increased the total and marketable yield of onion bulbs of Giza 20 cultivar grown under similar conditions of this work