2018 ASHS Annual Conference

Ripening in blueberry fruit occurs over an extended period requiring multiple harvests thereby increasing the costs of production. Several phytohormones contribute to the regulation of fruit ripening. Certain plant growth regulators (PGRs) can alter the content, perception or action of these phytohormones, potentially accelerating fruit ripening and concentrating the ripening period. The effects of three such PGRs on fruit ripening were evaluated in rabbiteye blueberry (Vaccinium virgatum) cultivars ‘Premier’ and ‘Powderblue’. Application of ethephon, an ethylene-releasing PGR, at 250 mg L^-1 when 30-40% of fruit on the plant were ripe, accelerated ripening by increasing the proportion of blue (ripe) fruit within 4 -7 d after treatment in both cultivars. Ethephon applications did not generally alter fruit quality characteristics at harvest or during postharvest storage, except for a slight increase in ‘Powderblue’ fruit firmness and titratable acidity after 15 d of postharvest storage. Abscisic acid (600 - 1000 mg L^-1) and methyl jasmonate (0.5 mM – 1 mM) applications generally did not alter ripening characteristics in either cultivar. These applications also had little effect on fruit quality characteristics at harvest and during postharvest storage. None of the above PGR applications affected the development of naturally occurring postharvest pathogens that developed during storage. Together, data from this study indicate that ethephon has the potential to accelerate ripening in rabbiteye blueberry fruit allowing for a potential decrease in the number of fruit harvests.