Cutting propagation of Bornmuellera tymphaea, a nickel hyperaccumulator for use in agromining: Effects of rooting media and auxins on stem cuttings

The nickel hyperaccumulator Bornmuellera tymphaea has been evaluated for use in agromining in Greece with very promising results. This study examines propagation of this species based on cuttings, which provides rapid multiplication and clonal propagation of genotypes with useful genetic traits and offers obvious advantages over propagation by seed. Apical cuttings, 10 cm long, obtained from plants in the field, were propagated on mist benches under greenhouse conditions. Four treatments based on the rooting medium were evaluated: (a) perlite, (b) perlite + peat 1:1 (v/v), (c) ultramafic soil, and (d) ultramafic soil + perlite 1:1 (v/v). Completely randomized blocks were used in a 4 × 2 factorial design, using 4 different propagation rooting media and 2 levels of auxins (with or without the use of indole-3-butyric acid [IBA]), with 3 replicates of 28 cuttings. The response to perlite medium was best in terms of rooting: 75% without IBA and 71.33% with IBA, and the dry weight of roots was 0.18 g and of shoots 0.34 g. Perlite + peat 1:1 (v/v) medium also resulted in rooting in more than 55% of cuttings whereas cuttings grown in ultramafic soil showed very low rooting (<27%). Based on the findings, B. tymphaea has an aptitude for vegetative propagation by cuttings with survival values and rooting greater than 70%. Perlite combined with the application of auxin (ΙΒΑ) is recommended.