Effects of Combination Between Nitrogen and Potassium Fertilization on Yield and Quality of Valencia Orange Fruits

Nitrogen (N) and potassium (K) are the most important nutrients for fruit yield and quality of citrus. Farmers - growing orange is usually applied high rates of N and K fertilizers. The study was carried out during 2017 and 2018 production year on a 4-year Valencia orange. The objective of the present paper was to evaluate the effect of combination between nitrogen and potassium on fruit yield and quality of Valencia orange. The experiment was used three doses of N (0.5, 1.0, and 1.5 kg/tree) in form of urea and three doses of K (0.6, 0.9, and 1.2 kg/tree) in form of potassium chloride in all combinations. The obtained results showed that N and K concentrations in soil did not increase with increment of N and K fertilization. Increment of N and K fertilization increased N content but did not increase K content in leaves. Fruit weight, fruit diameter and peel thickness increased with increasing of N fertilization. Maximum fruit yield of Valencia orange was attained with rates of 0.5 kg N/tree combined with 0.9 kg K/tree. Juice content increased with increasing amount of N fertilization. Increment of K fertilization tend to increase total acidity in fruit juice. The highest TSS and TSS/TA were attained with rates of 0.5 kg N/tree combined with 0.9 kg K/tree.