Study of effects of different sources of Azot on the quality and quantity of thomson navel orange on citrumelo root stock

Nitrogen is considered as an important and vital element for citrus trees which it,s offer can be controlled by man. It is found in chlorophyll, in the amino acids from which proteins are made, and in the nucleic acid so the first nitrogen deficiency symptoms are pale green to yellow leaves. Nitrogenous compounds of leaves may be transported to the another parts of tree that needs to it. For example when deficiency of nitrogen in a part of plant take places this element will transport to the parts that have higher potential for absorption of nitrogen, so the highest level of nitrogen can be found in fruits and aged leaves have lowest nitrogen content. Nitrogen absorption is done in form of nitrate(NO3-) mainly and in hydrogenate conditions some of absorption take place in form of ammonia. The main sources of nitrogen fertilizers in Iran is include urea, urea with cover of sulfur, ammonium sulfate and ammonium nitrate. A glance to mobility of nitrates in the soil can lead us to this fact that the properly selection of nitrogen fertilizers can be a vital decision for achieving the highest efficiency of used fertilizer and prevention of environmental pollution. Therefore we must evaluate the different sources of nitrogen fertilizers for achieving the highest quantity and quality of yield. This study was conducted during 5 years with 5 years old Thomson sweet orange(Citrus sinensis Osbeck) trees which grafted on citrumelo rootstocks in Khoram- Abad station of Citrus Research Institute in Tonekabon city. All of cultural practices was done similarity for total trees.This experiment was done based on Randomized Complete Block Design(RCBD)with 7 treatments and 5 replications for each treatment. We used two trees for every treatment and finally 70 trees were used in this research. Treatments are as follows: A: 200gr ammonium nitrate × Age of tree ( as local common low) B: 120 gr ammonium nitrate × Age of tree C: 120 gr urea with cover of sulfur × Age of tree D: 50 Kg animal manure for each tree in each year AD: (100 gr ammonium nitrate × Age of tree) + 25Kg animal manure BD: ( 60gr ammonium nitrate × Age of tree) + 25Kg animal manure CD: (60 gr urea with cover of sulfur × Age of tree) + 25Kg animal manure Each studied tree taken 300 gr. Super phosphate triple and 750 gr. Potassium