MITIGATION OF HEAT STRESS EFFECTS BY USING SHADE NET ON WASHINGTON NAVEL ORANGE TREES GROWN IN AL-NUBARIA REGION, EGYPT

High temperature stress can be detrimental to plants, resulting in reduced fruit yield and increased incidences of fruit disorders. One strategy that farmers can use to maintain or increase their yields in the face of a changing climate is to adjust of farm climate by using shade net on the trees. Such, the use of shade netting on Washington navel orange planted on the sandy soil in Al-Nubaria region, Egypt were studied during two successive seasons, either using a permanent shade throughout all the season or using a moveable shade for certain period from the first of March until the end of June for every season. Growth (No. of shoots/one meter branch, No. of leaves/shoot, shoot length and chlorophyll content of the leaves, leaf area and tree canopy), macronutrients (N, P, K, Ca, Mg) and micronutrients (Fe, Zn, Mn, Cu, Na) content in the leaves, fruit characteristics (number, weight, diameter, peel thickness, total soluble solids, total acidity and ascorbic acid), yield and crop efficiency, were determined. It can be concluded that covering Washington navel orange trees grown on sandy soil with shade net especial covering the trees for certain period was very effective at protecting orange trees and led to improve the growth, increase the yield and maintain fruit quality.