Micropropagation of blueberry 'Bluejay' and 'Pink Lemonade' through in vitro shoot culture

This study systematically evaluated effects of culture media, cytokinins, and auxins on axillary shoot induction as well as auxins and media or substrates on in vitro and ex vitro rooting of a highbush cultivar Bluejay (Vacciniwn corymbosum L.) and a V. ashei rabbiteye hybrid derivative 'Pink Lemonade'. Optimal protocols for in vitro shoot culture of the two cultivars were developed. Two-node stem explants derived from axillary shoots were cultured on Anderson medium supplemented with 13.68 mu M 6-(4-hydroxy-3-methylbut-2-enylamino) purine (ZT) and 0.27 mu M naphthaleneacetic acid (NAA) for inducing axillary shoots of 'Bluejay' and 9.12 mu M ZT and 0.05 mu M NAA for 'Pink Lemonade' shoot proliferation. Microcuttings derived from the axillary shoots were cultured on half-strength Anderson medium supplemented with 0.49 mu M indole-3-butyric acid (IBA) for in vitro rooting. The rooting percentages for 'Bluejay' and 'Pink Lemonade' were 75% and 65% in two months, respectively. However, by dipping microcuttings into 4.92 mu M IBA for 10 s and rooting ex vitro in a substrate composed of 90% peat and 10% perlite, the rooting percentages could be improved to 89% for 'Bluejay' and 97% for 'Pink Lemonade'. After being acclimatized in a shaded greenhouse for three months, rooted plants were ready for planting in the field. The established methods could be used for rapid propagation of highbush and rabbiteye hybrid derivative cultivars for commercial blueberry production.