Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 12/2/2016
Publication Date: 11/1/2017
Citation: Sampson, B.J., Shaw, D.A., Stringer, S.J., Sakhanokho, H.F., Werle, C.T. 2017. Novel formulation of gibberellic acid and coconut oil fatty acids to enhance rabbiteye blueberry maturation, berry size, and yield . Acta Horticulturae. 1180, 31-38. DOI: 10.17660/ActaHortic.2017.1180.5 https://doi.org/10.17660/ActaHortic.2017.1180.5..
Interpretive Summary: A new formulation of 0.5% coconut oil soap or ~0.05% coconut oil added to the plant hormone, gibberellic acid (also called gibberellin A3 or GA3) was discovered to accelerate ripening in fruit from flowers on four rabbiteye blueberry cultivars. The soap also increased fruit weight for six tested cultivars, and increased sugar content and seed set in two cultivars. The coconut oil soap emulsion at concentrations from 0.5 to 1.0% mimicked the effects of cross-pollination and could be used to rescue blueberry crops when flowers are damaged by frost and insect pests or when flowers are poorly pollinated by bees.
Technical Abstract: This paper provides a summary of results presented in a much more comprehensive article (Sampson et al. 2014). Specifics regarding methods and statistical procedures can be found in Sampson et al. 2014. Here, we summarize these results for popular cultivars of rabbiteye blueberry (V. virgatum syn. ashei Reade) that produce upwards of 90% deformed “zygomorphic” blooms as well as other cultivars that do not. One cultivar in particular, Premier, by producing zygomorphic blooms, suffers losses in yield. Infertility of these zygomorphs might render plants less fruitful with yield losses reaching 67%. Other vulnerable rabbiteye blueberry cultivars include ‘Columbus’ ‘Yadkin’, ‘Montgomery’, and ‘Tifblue’. To ensure zygomorphic varieties remain fruitful, blooms dosed with gibberellin A3 (GA3) can achieve exceptionally high sets of small seedless fruit that mature 7 -14 days late. Our new GA3 formulation, which combines gibberellic acid with 0.05% coconut oil (or 5% coconut oil soap), yielded seedier faster-maturing berries rich in sugar (10% to 12% dissolved solids). Seeds appear to have arisen via apomixis perhaps induced by bioactivity of longer-chained fatty acids and cytokinins in coconut oil. Seed size for apomictic fruits varied considerably,; a few seeds were as large as those resulting from cross-pollination; most seeds were 3 – 4 times smaller in volume. Coconut fatty acids therefore function as possible synergists to GA3, producing marketable seeded berries.