Impact of sheep manure, urea and triple superphosphate on onions morphological properties

Onion (Allium cepa L.) is a vegetable that is widely consumed due to its flaouring and healthpromoting properties. A randomized complete block factorial experiment was carried out in Payame Noor University, Marivan center, in order to study the effects of rates of nitrogen, phosphorus and sheep manure on the yield and quality of onion. The first factor consisted of two sheep manure levels (0 and 5 ton/ha), the second factor consisted of three triple superphosphate levels (0, 100 and 150 kg/ha) and the third factor consisted of three urea levels (0, 150 and 300 kg/ha). The results indicated that the morphological properties significantly improved in sheep manure treatment. Phosphorus treatment significantly improved the morphological properties of onion. Urea treatments increased the fresh and dry weight, volume and bulb diameter of onion. The highest nitrate concentrations resulting from urea rate of 300 kg/ha.