effect of soil nitrogen fertilizer on fruit set, the yield and fruit quality of Valencia orang trees.

This experiment was carried out during 2018/2019 and 2019/2020 seasons on Valencia orange trees cultivated on clay soil located at Mallawy district to investigate the effect of different nitrogen doses on the yield and its fruits quality. Different Nitrogen applications at 600, 900 and 1200 g N/ tree in the form of ammonium nitrate (33.5%) were added annually per tree in two or three equal batches at Mid- November and first week of December and Mid- November, first week of December and Last week of December. In addition to the control 1000 g N / tree at three equal batches, at the start of spring growth cycle, just after fruit setting and at two months later. Increasing the nitrogen doses was very effective in increasing fruit set, the yield per tree and fruit quality. The best results concerning yield and fruit quality were presented by adding 1200 g N /tree annually at three equal batches.