Two field experiments were conducted during 1995/96 and 1996/97 seasons at the Agricultural Experimental Farm of Suez Canal University at Ismailia to study the effect of three levels of phosphatic fertilizer i.e. 0, 15.5 and 31 Kg P₂O₅/fad and foliar nutrition with potassium solution (36% K₂O) at a rate of 1.5cm³/L and magnesium sulphate (49% Mg SO₄) at a rate of 1 g/L on growth, yield, yield components and yield quality of two lupin varieties.                 The obtained results revealed that Balady variety significantly surpassed Roomy variety in plant height, dry weight of leaves, stems and roots/plant, number of pods/plant, pods and seed yields/plant, number of seeds/pod, shelling percentage, seed yield/fad and seed protein content %. While, Roomy variety had heavier 100-seed weight compared to Balady variety.                 Applying  phosphorus fertilizer up to 31 Kg P₂O₅/fad significantly increased the different studied growth characteristics, chlorophyll content in the leaves, yield, yield attributes and seed protein content %. Meanwhile, increasing P levels did not affect significantly number of seeds/pod. Also, foliar spraying with potassium or magnesium significantly increased all the studied traits compared to control, except number of seeds/pod which was not affected by foliar application of K or Mg. It is worthy to mention that foliar nutrition with potassium significantly exceeded magnesium in seed yield/plant, 100-seed weight and shelling percentage.                 The all possible interactions between varieties, phosphorus rates and foliar nutrition affected significantly almost all the studied traits.                 It is worthy to note that lupin plants received  15.5 Kg P₂O₅/fad and sprayed with K or Mg surpassed unsprayed plants fertilized with 31 kg P₂O₅/fad in seed yield per fad.                 It is could be concluded that foliar nutrition with K or Mg increased the efficiency of lupin plants in utilizing phosphorus fertilizer which reflected in enhancing growth and yield attributes consequently, increasing seed yield. On the other hand, foliar nutrition with K or Mg could save a significant amount of the phosphorus fertilizer.                 The highest seed yield/fad was obtained from Balady variety fertilized with 31 Kg P₂O₅/fad and sprayed with potassium.                 There was a positive and significant correlation between lupin seed yield/fad and different studied growth traits, chlorophyll content, number of pods/plant, seeds/pod, pods and seed yields/plant and shelling percentage.