Nutrient and bio-stimulant amendments are important for growth, yield, and quality of fruit crops under environmentally stressed site conditions. Our field study was conducted to evaluate the effect of potassium fertiliza- tion and yeast extract on growth, yield and finger quality of banana grown under arid and semi-arid marginal site conditions in Egypt. Using different levels of Potassium at 500 & 1000 mg as a foliar application and yeast extract at one & two liters per plant as a drench soil application and their combinations doses added monthly six times during the period from October to March. The obtained results showed a positive correlation between the values of the studied parameters (growth, productivity and fruit quality) and the yeast and potassium levels. As a result, the parame- ters values increased as the yeast and the K2SO4 levels increased to a higher level during the two growing seasons. Herein, yeast extract 2000 ml þK2SO4 1000 mg/l/plant was statistically the superior. In addition, yeast extract 2000 liters þK2SO4 500 mg/l/plant statistically ranked 2nd after the above-mentioned superior treatment. On the contrary, the lowest val- ues of these parameters were obtained by Control yeast extract 1 liter/ plant. The remaining treatments have occupied an intermediate position between the treatments mentioned above in both seasons.