Effect of Ammonium Nitrate and Potassium Sulphate on Growth and Yield Characteristics of Onion

In order to study the effect of ammonium nitrate and potassium sulphate on growth characteristics of onion (Allium cepa L. cv. Azar Shahr) a factorail experiment was carried out in a randomized complete blocks design with four replications. Treatments were consist of NH4NO3 (22. 5، 45، 67. 5 and 90 kg/ha) and K2SO4 (0، 78. 3 and 156. 6 kg/ha). The experimental results showed that bulb diameter، plant height، number of leaf، leaf area، bulb fresh and dry weight، leaf fresh and dry weight and leaf chlorophyll index significantly affected by application of NH4NO3 and K2SO4. From the experimental results it can be concluded that applying of 90 kg/ha NH4NO3 and 156. 6 kg/ha K2SO4 increased leaf chlorophyll index، bulb diameter، plant height، leaf area and leaf fresh and dry weight، whereas، the highest fresh weight of bulb was obtained by supplying 67. 5 kg/ha NH4NO3 and 78. 3 kg/ha K2SO4. Furthermore، increasing the NH4NO3 content reduced both bulb dry weight and number of leaf.