Influence of Irrigation methods and foliar applicationof Potassium silicate on the growth and productivity of Valencia orange trees (Citrus sinensis L.) grown under Delta conditions.

In Egypt, water shortages increase annually due to various factors. In Delta region, most citrus growers use flood irrigation systems whereas irrigation water is frequently applied to each furrow leading to the loss of huge amounts of water. This work hypothesized that Valencia orange trees grown on raised beds irrigated with alternate floods or fixed furrows based on principles of partial root-zone drying could maintain tree vigour, yield, fruit quality, sustain citriculture, and save irrigation water in Delta region. To test this hypothesis an experiment was conducted in the 2020 and 2021 seasons at commercial orchards in Kalubia governorate to assess tree canopy, yields, fruit quality, leaf nutrient contents, and water productivity of Valencia orange trees budded on Sour orange rootstock. Five treatments were used in the investigation farmer’s method as a control (both furrow irrigation), substitute furrow irrigation (SFI) with foliar application of 2000 ppm potassium silicate (K₂SiO₃), SFI + 4000 ppm (K₂SiO₃), irrigation with fixed furrows (IFF) + 2000 ppm (K₂SiO₃), and IFS + 4000 (K₂SiO₃). Obtained results indicated that various treatments were associated with a significant reduction in the tree canopy, leaf area, and leaf N content while increasing leaf P, K, Si, and free proline content compared to control and significantly improved fruit quality parameters. Treatment of (SFI with 2000 ppm K₂SiO₃),)was regarded as the best combination treatment for enhancing tree canopy, yield, and fruit quality parameters and saving about 33% of irrigation water in both study seasons.