Vegetative Growth and Quality of Washington Navel Orange as Affected by Shading Nets and Potassium Silicate Spraying

Abstract

The experiment was conducted on Washington navel orange trees grown in sandy soil under a drip irrigation system at El Nubaria, Behera governorate during both experimental seasons of 2018 and 2019 to study the effect of applying a shading net, spraying potassium silicate, and their combination during fruit development to reduce high-temperature stress on fruit drop (%), number of fruits sunscald, number of fruits/ tree, and fruit quality, the experiment followed Randomized Complete Block Design(RCBD). The results showed that, T4 (Shading net (75%) and T7 (Shading net (75 %) + potassium silicate) caused the highest significant increase in shoot length. in the first season, the two shading treatments (T3 and T4) and the three combined treatments (T5, T6, and T7) caused a significant increase in leaf area compared to the control and the rest treatments. In the first season, Treatments (T4, T6, and T7) caused a significant increase in shoot diameter compared to the rest treatments and the control. In the two seasons, control, and the treatments of spray silicate only (one, two, or three times) caused the highest significant percentage of fruit June drop compared to the rest treatments. All treatments caused a significant increase in average fruit weight (g), juice weight (%), and fruit diameter (cm) compared to control. T2 (35% shading net) caused a significant increase in TSS and TA (%) compared to the control and the two shading treatments (65 and 75%). As for vitamin C shading treatments (T2, T3, and T4) did not show any significant differences among them or compared to the control. The highest value of total chlorophyll was obtained from T4 and T7.