Effect of Phosphate and Potassium Fertilizer Rates on Potato Plants Grown under Water Stress Conditions

The effect and relationship between water stress, potassium (K) and phosphorus (P) fertilizers rates on water consumptive use, water requirements, and yield of potato cv. Valor was studied under field conditions at Dokki Protected Cultivation Experimental Site, Agricultural Research Center (ARC), Giza Governorate, Egypt. The study concerned with the use of different rates of K fertilization (50, 100 and 150 kg K2O/fed) and P fertilization (50 and 100 kg P2O5/fed) under different irrigation scheduling (100, 75 and 50% of irrigation requirements by Penman-Monteith method) on potato crop cultivated in alluvial soil. The highest plant growth was recorded when water irrigation level reached 75% of irrigation requirement in the presence of 100 kg P2O5/fed and 150 kg K2O/fed. Results also revealed that more or less similar values of macronutrient uptake were found in plant leaves at different treatments. Finally, results obtained indicated that this treatment is the most effective treatment on growth parameters also recorded the highest tuber yield and its content from carbohydrates and protein. Thus, farmers should not supply water irrigation of potatoes more than 75% of irrigation requirement to obtain economic tubers.