Currently every country is suffering from climate change and despite the ongoing efforts, there are still limited success stories for the improvement of plant abiotic stress resilience. The studies mainly focused on understanding the stress response and tolerance at the molecular level and utilizing it to another genotype with no tolerance. The strong interaction of plants with their environment is the main obstacle here, which prevents the outcomes of small-scale experiments to be repeated in the field. The inclusion of wild genotypes adapted to extreme environments in QTL studies and breeding efforts may stand as a promising approach for the improvement of abiotic stress tolerance. Agricultural practices including biostimulants, micronutrients and nanoparticles, genome editing, and engineering organelles can also lead to reduced yield loss. Understanding how stress memory is initiated and how to make it heritable even under favorable growth conditions is another approach that needs more investigation. The aim of this book chapter is to point out the fact that single efforts by themselves will not be enough for sustainability, and although there is still a gap between breeders, farmers, biodiversity scientists, agricultural engineers, molecular scientists, plant pathologists, and climate scientists, they should combine their knowledge to secure future generations.

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 1st week to October 1st week). The results demonstrated that five applications of 200 µg/ml L-proline foliar treatment might significantly boost Balady mandarin quality. Consequently, using this eco-friendly fertilizer under the climatic conditions of Assiut is recommended.

Pomegranate growers in Egypt have been struggling with a variety of production issues, including splitting, sunburn, and a lack of proper colour intensity and consistency, which are major barriers to attaining high quality fruit. The current research aims to evaluate the impacts of calcium chloride (CaCl2), potassium nitrate (KNO3), and flower thinning on reducing these problems and enhancing fruit quality. Seven treatments were carried out, including foliar application with CaCl2 2 and 4%, KNO3 250 and 500 ppm alone or combined with flower thinning and control (spraying with water). The spraying treatments took place three times, at the beginning of flowering (in Apr.), after fruit set completion (first Jul.), and before harvest (first Sept.), during the two study seasons. Hand flower thinning was done to all of the flowers that surged from the last week of May until the end of the flowering period. The obtained results indicated that spraying 500 ppm KNO3 or 4% CaCl2 alone or combined with flower thinning are regarded as the best treatments in terms of their impact on the yield components, fruit quality, anthocyanin content, and reducing fruit cracking.

Currently, nanotechnology is widely used in agriculture and horticulture. Nanofertilizers are essential for encouraging vegetative growth and flowering, as well as enhancing productivity and fruit quality. These nanoparticles are viewed as growth promoters as well. The current study was therefore carried out during the two successive seasons of 2021 and 2022 on 14-year-old trees grown in clay soil in a field experiment at the Pomology Department Research orchard, Faculty of Agriculture, Assiut University, Egypt. The effects of conventional vs. nano-micronutrients as foliar fertilizers on the fruit yield, quality, and mineral nutrition status of pomegranate trees were studied. The foliar application of all treatments on pomegranate trees remarkably increased yield and physical properties of fruits as well as improved the levels of total soluble solids percentage, anthocyanin pigment, flavonol, total phenols, antioxidant activity and nutrients status compared with the controls during the 2021 and 2022 seasons. The lowest fruit cracking percentages were obtained by the spraying of nano-micronutrients (4.33–5.70 %) compared with the other treatments and the control, which gave the highest percentages (10.45–11.43 %). The highest increments in yield, physical properties of fruits and levels of total soluble solids percentage, anthocyanin pigment, flavonol, total phenols, and antioxidant activity were noticed by the spraying of nano-micronutrients especially at 1000 and/or 1500 µg mL⁻¹. It could be concluded that the use of nanofoliar fertilization in pomegranate cultivation may improve the yield, quality, and nutritional status of pomegranate fruits.