Alanine conjugate of indole-3-butyric acid improves rooting of highbush blueberries

Auxins and their synthetic analogues are commonly used for rooting of cuttings, but their efficiency depends on experimental set-up and, even more importantly, on species or cultivar, and type of explants investigated. In attempt to improve rooting procedure for highbush blueberries (Vaccinium corymbosum L.), we investigated alanine conjugate of indole-3-butyric acid (IBA-Ala) as potential root-promoting compound and compared with commonly used auxins indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA). The effect of different concentrations of auxins on the rooting of highbush blueberry stem cuttings (var. Bluecrop, Bluetta, Burlington and Jersey) and in vitro-derived microcuttings (var. Jersey) was investigated. Auxin treatments significantly promoted rooting of all four varieties in comparison to control. The most efficient rooting promoter in all varieties appeared IBA-Ala (provided up to 83%, and 93% of the rooted cuttings and microcuttings, respectively). Furthermore, IBA-Ala caused a vigorous, well-branched root system that resulted in better acclimatization and survival of plants. Results suggest the application of IBA-Ala may be beneficial for rooting of difficult-to-root varieties of blueberry and related species and their practical application in the nursery industry.