Environmental factors and physiological responses of sweet cherry production under protective cover systems: A review

Climate change is increasing sweet cherry ( Prunus avium (L.) L.) production under cover systems such as high tunnels, rain covers, and nets. The objective of this review was to provide an overview of the environmental factors and physiological responses involved in cherry production under different types of protective covering systems. The most important environmental factors affected by cover systems are photosynthetically active radiation (PAR), temperature, relative humidity, and wind speed, which in turn affect leaf gas exchange, plant water relations, tree growth, flower development, and fruit quality. The use of covering systems has a positive effect on photosynthesis by increasing the amount of diffused PAR, but a negative effect on the reproductive-vegetative tree balance due to lower total PAR availability. Increases in air temperature by cover systems alter differentially flowering and fruit set, impacting positively the ripening time and cell division of the fruits. Plant water status is improved under cover systems, allowing for greater tolerance to water deficit as well as improved potential fruit cell expansion, with an ensuing positive effect on fruit size, but decreasing fruit firmness due to lower Ca availability fruits. The multiple environmental factors and physiological responses observed in cherry production under cover systems suggest the need to adjust agronomic practices such as pruning, crop load regulation, irrigation, and nutrition according to these specific conditions.