Growing citrus fruit trees became more expensive over the last few years as a result of rising production costs. Thus, less environmentally harmful methods were employed in an effort to find a technique to lower these costs while obtaining a high yield and quality of fruits free from any chemical residues. This study was carried out during two consecutive seasons of 2020 and 2021 on 15 uniformed Balady Mandarin trees, 20 years old, budded on sour orange rootstock, and planted at a distance of 5×5 m in the productive farm at the Agricultural Research Center in Shandawel Island, Sohag Governorate. The experiment aims to study the influence of girdling and cincturing on the fruit setting and yield of Balady mandarin trees. The results showed that all girdling and cincturing treatments (girdling or cincturing the trunk or branches) had a positive effect on flowering, fruiting, leaves content of carbohydrates, yield, and some fruit quality properties (TSS and TSS/acid ratio), while they led to a decrease in the leaves content of nitrogen in Balady mandarin trees under the climatic conditions of Sohag Governorate. The study recommends the importance of girdling the branches and trunk of the Balady mandarin trees under Sohag conditions to enhance the yield and quality of the fruits.

Heat stress has always been a major determinant of mandarin production in Upper Egypt. To reduce the negative effects of such climatic changes on the mandarin trees in Assiut, proline was used to make the trees able to withstand these changes. Herein, the experiments were executed throughout two successive seasons (2019/2020 and 2020/2021) at the experimental orchard of Assiut University, Faculty of Agriculture, Egypt, on twelve uniform Balady mandarin trees in a complete randomized-block design (3 treatments x 4 replications). The main objective of this study was to enhance the fruit quality of the Balady mandarin cultivar by using different concentrations of L-proline (100 and 200 µg/ml) under Assiut conditions. Balady mandarin trees were exposed to L-proline five times through the fruit-growing period (every 30 days from June 1 st week to October 1 st week). The results demonstrated that five applications of 200 µg/ml Lproline foliar treatment might significantly boost Balady mandarin quality. Consequently, using this eco-friendly fertilizer under the climatic conditions of Assiut is recommended.