Environmental conditions during preharvest influence bioactive compounds in fruits: A review with emphasis on tropical and subtropical species

A healthy diet rich in fruits and vegetables with high contents of bioactive compounds and antioxidants has become an essential habit among the human population, leading to a significant increase in the commercial trade of many fruits, especially of tropical and subtropical origins. The content of phytonutrients in fruits depends on various pre-harvest factors, especially agroclimatic conditions of temperature, light, and air humidity, as well as crop management and fruit maturity stage. Among the essential phytonutrients found in fruits that promote health and prevent diseases are the carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein, etc.), phenolic compounds (flavonoids, phenolic acids, among others), monoterpenes (i.e., limonene), isoprenoids (i.e., lipophilic vitamins), and ascorbic acid. Factors of temperature, light intensity, UV light, and water stress promote the synthesis of phytochemicals in fruits. In contrast, an excess of these factors can either increase or decrease the accumulation of these compounds in fruits. In addition to different abiotic stresses that result from climatic conditions and have inter- and intra-annual variations, the geographical locations, elevation, and genotype influence the content of bioactive compounds in fruits. There is a strong interest in manipulating changes in climate conditions as a factor in fruit quality, including the phytochemical content, while reducing yield losses. This review aimed to explore how preharvest environmental factors affect accumulation of phytochemicals in fruits, which are important for plant resilience and human health, with an emphasis on tropical and subtropical fruit species.