Evaluation of Container Grown Blueberry Cultivars and the Effects of Gibberellic Acid on Fruit Set and Fruit Quality

Abstract

There is increasing market interest in blueberry as a container ornamental plant with intact flowers or fruit for retail sale to home owners. The objective was to evaluate the performance of several blueberry cultivars as container ornamental plants under natural day conditions in an unheated greenhouse in Gainesville, FL, and the potential for use of gibberellic acid sprays (GA3) to increase fruit set without decreasing fruit quality. The three southern highbush (Vaccinium corymbosum) cultivars tested (‘Sunshine Blue’, ‘Emerald’, and ‘Biloxi’) had high reproductive bud count (109, 59, and 83 buds per plant, respectively). ‘Sunshine Blue’ had the earliest flowering of these three cultivars (13 Dec. 2013, 17 Jan. 2014, or 5 Jan. 2014, respectively). The upright habit and poor branching of ‘Biloxi’ were not desirable attributes as an ornamental container plant. Gibberellic acid (GA₃) was applied to ‘Emerald’ and ‘Sunshine Blue’ at 100 mg·L-1 GA₃ as a foliar spray three times 14 days apart, beginning when each cultivar had the maximum percentage of open flowers. Gibberellic acid (GA₃) hastened date of first green fruit by 17 days and increased fruit number by 47% (to an average 72 fruit/plant), but did not affect the date of first ripe fruit. Fruit weight was increased by 25% using GA₃, but there was no effect on sugar or acid content. Ornamental production of ‘Sunshine Blue’ and ‘Emerald’ using gibberellic acid (GA₃) sprays in greenhouses where pollinators may not be present produced attractive fruiting blueberry plants.