Selected Guava (Psidium guajava L.) clone of 11 years old, cultivated in clay soil were sprayed with potassium nitrate at 2 & 4 and 6% or ammonium sulphate at 5&10 and 15% at bloom stage. Floral abscission, after two weeks after spraying was enhanced by the two chemical application. Moreover, maximum floral abscission was recorded when trees received to 6% potassium nitrate followed by sprayed with 15% ammonium sulphate. Whereas, the lowest fruit retention of summer crop was caused by 6% potassium nitrate, followed by the ammonium sulphate at 15%, while the control trees recorded the maximum fruit retention. The yield of winter crop was significantly increased by application of potassium nitrate at 6% followed by ammonium sulphate at 5%. Yet, the winter fruits produced from potassium nitrate at 6% or ammonium sulphate at 15% exhibited the highest weight and diameter as well as produced higher T.S.S with low acidity.