Stimulation of adventitious root formation by laser in rose cuttings

Wounding is a fundamental factor effecting the survival of woody cuttings for plant propagation. Adventitious rooting is directly related to mechanical damage as a result of plant detachment. In this sense, methods of manipulating wounded regions to stimulate adventitious roots have most frequently been applied to hardwood species. Our first experiments investigating the role of wounds in cutting propagation of woody species indicated that additionally injured tissue along the cutting base showed an apparent increase in rooting compared to uninjured controls. Over time, a more detailed study of the effects of wounding on cuttings was investigated by the use of a laser as a wounding-tool. The aim of the present project was to implement laser-assisted tissue removal to study the effects of wounding on the induction of adventitious roots of leafy rose cuttings. Earlier experiments conducted with cuttings of two rose genotypes, R. canina and Rosa hybrida ‘Beluga’, demonstrated the laser’s ability to perform a large number of wound treatments based on different marking patterns and varying levels of tissue exposure. By developing a laser wound marking protocol, specific tissue layers could be targeted in a reproducible manner, depending on the energy applied per surface and the diameter of the rose cut. Results demonstrated that wounding would induce roots when tissue damage exposed regions near the phloem without the need to expose deeper layers. Moreover, analysis showed different effects from the wounding pattern or the tissue penetration. A detailed study of root positioning showed that the laser was clearly able to stimulate root formation directly in the marked zones depending on the rose genotype. This demonstrated the potential of manipulating laser root positioning in conjunction with the presence of exogenous auxins. The response of cuttings to laser-assisted wounding offered the opportunity to better understand the mechanism by which wounding can stimulate rooting in cuttings and will contribute to identifying the essential parameters that can improve the propagation of species by cuttings in commercial tree nurseries.

Raúl Javier Morales Orellana won the ISHS Young Minds Award for the best poster presentation at the International Symposium on Innovation in Ornamentals: from Breeding to Market at IHC2022 in France in August 2022..

Raúl Javier Morales Orellana, Biosystems Engineering Laboratory (BLab), Faculty of Agricultural Sciences and Landscape, University of Applied Sciences Osnabrück, Am Krümpel 31, 49090 Osnabrück, Germany, e-mail: r.morales-orellana@hs-osnabrueck.de

The article is available in Chronica Horticulturae