Effects of exogenous abscisic acid on fruit quality, antioxidant capacities, and phytochemical contents of southern high bush blueberries

Abscisic acid (ABA) is a plant growth regulator that has a potential to increase antioxidant capacity and phenolic content of fruits and vegetables. The objective of this study was to examine whether an exogenous ABA application can positively affect fruit quality, antioxidant capacity, and phytochemical content of southern high bush blueberries (Vaccinium darrowii). Two varieties, namely Star and Windsor, were tested with ABA water solutions of three concentrations (0, 200, and 400 ppm) using a randomised complete block design. Results showed that ABA significantly increased the firmness of berries in both varieties, suggesting a ripening delay effect. Such effect was more pronounced in Windsor variety as reflected by a lower percentage of ripe berries and smaller sized berries on ABA treated bushes. In conclusion, ABA delayed the ripening of blueberries, but did not affect total phenolic content, antioxidant capacity, or the content of individual phytochemicals in ripe blueberries.