Effect of some Natural Extracts on Productivity and Quality of Valencia Orange under New Valley Conditions

A two-year field experiment was conducted (2019-2020) at Afak Farm, Balat district, New Valley, Egypt, to evaluate the effects of foliar applications of natural biostimulants (yeast, Kelpag, Bio-power) on the productivity and fruit quality of eight-year-old Valencia orange (Citrus sinensis L.) trees. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications and seven treatments: T1 (control, distilled water), T2 and T3 (yeast at 10 and 20 g/L), T4 and T5 (Kelpag at 10 and 20 g/L), and T6 and T7 (Bio-power at 10 and 20 g/L), Foliar sprays were applied twice: two weeks after fruit set and ten days later. Assessed parameters included flowering characteristics, fruit retention, leaf nutrients (N, P, K), yield, and fruit quality. Results showed that all treatments significantly increased the number of leafy and woody inflorescences, flower quantity, and fruit retention compared to the control. Leaf nutrient levels improved significantly, especially with Bio-power at 20 g/L. Yield, fruit weight, volume, pulp percentage, total soluble solids (TSS), juice content, and ascorbic acid improved, while total acidity decreased. The most pronounced improvements were with Kelpak at 20 g/L: yield per tree increased by 13.8%, fruit weight by 3.5%, and TSS by 14.7% compared to control. No significant differences among the three biostimulants at the 20 g/L rate. Findings suggest that foliar application of yeast, Kelpak, or Bio-power at 20 g/L enhances growth, yield, and fruit quality of Valencia orange under arid conditions, with Kelpak showing a slight advantage in quality parameters.