Improving the in vitro rooting of micro-shoots of Sorbus rotundifolia ‘Bükk szépe’ by the sequential application of Humus® FW and Wuxal® Super organic and chemical fertilisers

SummaryThe aim of the present work was to enhance the in vitro rooting ability of an endemic species of sorb (Sorbus rotundifolia ‘Bukk szepe’), which is important as an ornamental tree species. The effects of Humus® FW applied to the root induction medium, and Wuxal® Super applied to the root elongation medium, on the rooting characteristics of microshoots were studied. Humus® FW is an organic fertiliser (Humin Project Ltd., Budapest, Hungary) containing mainly biologically-active, natural humic acids (including fulvic acid), while Wuxal® Super (WuxImpex Ltd., Budapest, Hungary) is a chemical fertiliser containing macro- and micro-elements (N, P, K, B, Cu, Fe, Mn, Mb, and Zn). Applying 1.5 ml l–1 Humus® FW during the root induction phase, then 1.0 ml l–1 Wuxal® Super during the root elongation phase, significantly improved in vitro rooting. The rooting percentage almost doubled (from 55% to 94%), and the mean number of roots per shoot increased three-fold (from 3.1 to 9.3). In vitro rooted shoots were su...