A field experiment was  carried out during the summer  seasons of 2018 and 2019 at Gemmeiza Agric. Res. Station, Gharbeya Governorate, Egypt to evaluate effects of  mineral and  organic nitrogen  as well as  using  vitamin C and  chitosan as foliar spray  on growth ,  yield  and fruit  quality of  sweet  pepper cv. California Wonder grown in clay soil. The interaction between fertilizing sweet pepper plant  with MN at 25 % RR+ON at  75 % RR and spraying  with Vit.C at 300 ppm  increased  plant height, number of leaves / plant, number of branches/ plant and shoot dry weight  at 90 days after transplanting in both growing seasons. However,  fertilizing  plants with MN  at 25 % RR +ON at 75 % RR and spraying with chitosan  at 2ml/l  or  Vit.C at300 ppm  increased N,P and K contents and their  uptake by shoot.  In addition, the interaction between fertilizing with MN at 25 % RR+ON at  75 % RR and spraying with chitosan at 2ml/l increased  average fruit weight, yield / plant and total yield /fed.  as well as  nitrogen use efficiency  and lowest values of nitrate content in fruits. Nevertheless, the interaction between fertilization  with MN at 50 %RR+ ON at 50 % RR and spraying with chitosan at 2 ml/l increased DM% in fruit, whereas the interaction between fertilizing  with MN at 50 %RR+ON at 50 %RR and spraying with Vit. C at 300 ppm  increased TSS and Vit.C in fruits in both seasons.