Emulsions of long-chain fatty acids as fruit sizing and ripening agents for gibberellin-A3-treated rabbiteye blueberries (Vaccinium virgatum Aiton syn. V. ashei)

Abstract Some rabbiteye blueberry cultivars ( Vaccinium virgatum Aiton syn . ashei ) lose ≤67% of their berries to a floral polymorphism ( z1-5 ) that reduces male and female function by deforming corollas, stamens, and pistils. These deformities give flowers an asymmetric shape, and if severe enough, could cause sterility. Overcoming sterility and associated yield loss in ‘Premier’ flowers was possible with two applications of an exogenous plant growth regulator (PGR), 250 ppm gibberellin-A 3 (GA). Interestingly, the dual emulsifier and surfactant chosen for our GA dips, 0.5% coconut oil soap, behaved like a PGR by inducing adventitious embyony, possibly apomixis. Resulting berries were 20–25% heavier and matured 7–14 days earlier. Fruit sets as high as 80–90% stemmed from the emulsion's GA ingredient. Yet, the heaviest seed-rich berries either resulted from cross-pollinated flowers or from unpollinated ones treated with GA/coconut oil soap emulsion (hereafter known as the emulsion). A second greenhouse experiment incorporated chemical dips containing four concentrations of coconut oil soap, five component fatty acids with medium length to long-chain aliphatic tails (C 10 –C 18 ), and three new cultivars. Again, these replicated trials achieved similar results. GA stimulated high fruit set, while coconut oil soap plus its component long-chained fatty acids produced heavier faster growing berries for unpollinated blooms of ‘Austin’, and ‘Prince’. ‘Tifblue’ flowers however yielded seedless fruit, indicating genotypic sensitivities to exogenous GA.