Effect of different rates of irrigation, soil conditioners, and potassium fertilizer on the productivity and fruit characters of Valencia orange trees (Citrus sinensis L.) growing under North Sinai conditions

Abstract Due to the water scarcity crisis that faces Egypt, there is more need for new management practice to sustain citrus production under sandy soil conditions. The investigation of different rates of irrigation, soil conditioners, and potassium fertilizer on the growth and productivity of Valencia orange trees was conducted in Baloza area of North Sinai. The treatments include two levels of irrigation (100% and 75% of field capacity) and soil application of two soil conditioners namely Super absorbent polymer (SAP) and Polyvinyl Chloride (PVC), were added (50 g/tree) on mid of January, and two rates of potassium fertilizers (450g and 340 g/ tree/yearly). The maximum plant growth parameters like canopy volume and chlorophyll leaf content recorded in the trees that received 50g SAP and 480g potassium per tree under full field capacity conditions, furthermore, various treatment enhancing the nutrition statues of trees in terms of N, K, P leaves contents, and reduce proline content. Highest fruit yield per tree (55.2 & 60.2 kg), fruit yield (t/ha), and fruit weight (190.0 & 191.9 g) were recorded in the trees that received 480 g potassium and 50g PVC under highest irrigation rate, while, the number of fruits per tree (303.8 &359.3) were maximizing in treatment of 75% Fc with PVC polymrt and low rate of K, in the first season and in treatment of 100% Fc withSAP polymer and low rate of K, in the second one. Furthermore, various treatments improved fruit characters such as fruit shape index, Juice ratio, and TSS/acid ratio.