Two field trails were carried out during two successive summer seasons of 1998 and 1999 at the Farm of El-Gemmeiza Agricultural Research Station to study the response of citron plants to biofertilizer (Phosphorien) at 3 kg/fed and mineral-P fertilizer at 0, 15, 30, 45 and 60 kg P₂O₅ / fed. in addition to their interaction on growth, yield and its components, fruit traits and chemical constituents in plant leaves. In general, the obtained results can be summarized as follows:- 1. Application of P-biofertilizer (Phosphorien) exerts significant increases in most studied characteristics of plant growth, yield, fruit traits and increased N, P and K concentrations in leaves compared with those of untreated plants. 2. All studied characteristics of plants received mineral-P were generally better than those of unfertilized ones. The highest values were obtained by using 30 kg P₂O₅/fed. 3. The interaction between phosphorien and phosphorus levels had significant effects on all studied characteristics. In general, treating citron seeds with phosphorien at 3 kg /fed in addition to 30 kg P₂O₅/fed gave the maximum yield.