Applicability of in vitro clonal hedge in the vegetative propagation of Eucalyptus urophylla

The most used method for the production of plantlets of the Eucalyptus has been the mini-cutting. Productivity in this system is closely linked to environmental and management conditions, with problems related to loss of physiological vigor and low rooting rates being common. In vitro culture techniques offer many advantages to the plantlets production, including the uniformity among propagules; multiplication of clones in reduced space and time; and the greater nutritional, environmental, and phytosanitary control. However, in vitro propagation is still a process that causes some stress to plants and also has limitations for commercial-scale use regarding clonal Eucalyptus production. In vitro clonal hedge is proposed to overcome some difficulties in the vegetative propagation found in the mini-clonal hedge located in forest nurseries adding the advantages of in vitro propagation, including photoautotrophic cultivation, to the conventional production technique by mini-cutting. This study compares the productivity of mini-stumps/micro-stumps of the Eucalyptus urophylla clone in two cultivation systems: the mini-clonal hedge located ex vitro, and the in vitro clonal hedge located in a tissue culture laboratory. Shoot production, rooting and mini-cuttings/micro-cuttings' survival were evaluated. The production of mini-cuttings/micro-cuttings by mini-stump/micro-stump was similar, but the productivity per area was higher in the in vitro clonal hedge. In both systems, high survival and rooting rates were observed. However, the in vitro clonal hedge systems aim to provide a new way of propagating vegetative plants, which should be further studied and improved to become an alternative to the mini-clonal hedge for the production of clonal Eucalyptus plantlets.

Automated summary

The mini-cutting method is widely used for Eucalyptus plantlet production, but it has issues with physiological vigor loss and low rooting rates. In vitro culture techniques offer advantages, but they still cause some stress to plants and have limitations for commercial use. This study proposes an in vitro clonal hedge system, combining traditional techniques, to overcome the difficulties in mini-clonal hedge propagation. High survival and rooting rates were observed in both systems. However, further research and improvement are needed for the in vitro clonal hedge system to become an alternative for clonal Eucalyptus plantlet production.