This paper summarizes the information on the occurrence of phenolic compounds in apple (Malus x domestica Borkh.) fruit and juice, with special reference to their health related properties. As phytochemical molecules belonging to polyphenols are numerous, we will focus on the main apples phenolic compounds with special reference to changes induced by apple cultivar, breeding approaches, fruit postharvest and transformation into juice.

The yield and quality of horticultural crops mainly depend on genotype, environmental conditions, and cultivation management. Abiotic stresses, such as adverse environmental conditions, can strongly reduce crop performance, with crop yield losses ranging from 50% to 70%. The most common abiotic stresses are represented by cold, heat, drought, flooding, salinity, nutrient deficiency, and high and low light intensities, including ultraviolet radiation. These abiotic stresses affect multiple physiological and biochemical processes in plants. The ability of plants to face these stresses depends on their adaptation aptitude, and tolerant plants may express different strategies to adapt to or avoid the negative effects of abiotic stresses. At the physiological level, photosynthetic activity and light-use efficiency of plants may be modulated to enhance tolerance against the stress. At the biochemical level, several antioxidant systems can be activated, and many enzymes may produce stress-related metabolites to help avoid cellular damage, including such compounds as proline, glycine betaine, amino acids, etc. This special issue gathers eight papers; three are reviews and five are research papers. Two reviews are focused on the application of appropriate agronomic strategies for counteracting the negative effects of abiotic stresses. The third review is based on ornamental plant production under drought stress conditions and the effect on their ornamental quality. The research papers report the effect of climate change on crop development, yield, and quality. Abiotic stresses have been proven to reduce crop performance and yield. Research studies are essential for understanding the key adaptation strategies of plants that can be exploited for improving the crop stress tolerance.

Urban areas can be differently anthropized; often, high-density populations lead to higher amounts of pollution. Nowadays, ornamental plants can represent important living components of urban areas, and if appropriate species are used, they can provide important ecosystem services. The relationships between green infrastructures and ecosystem services have been recognized for a long time, but the role of ornamental plant species has not been studied as much. In this frame, the different ecosystem services of ornamental plants, i.e., provisioning (e.g., food, air, and water cleaning), regulating (e.g., rain water, climate, nutrient recycling, pollination, and the formation of fertile soils), and cultural (e.g., recreation opportunities or the inspiration we draw from nature) will be critically analyzed to select the most suitable ornamental plant species able to assure the better performance. The action mechanisms will also be analyzed and discussed to individuate the best ideotypes of plant species able to better assure water purification, air quality, space for recreation, climate mitigation and adaptation, human wellbeing, and health. This information is suitable to ensure that the protection, restoration, creation, and enhancement of green infrastructure become integral parts of urban spatial planning and territorial development.