Cuttings transplanted 30 May 2022. The photo is taken 30 July 2022. The pen is 15 cm long. Photo: Ra…
Cuttings transplanted 30 May 2022. The photo is taken 30 July 2022. The pen is 15 cm long. Photo: Rakel J. Jónsdóttir

Given there is sufficient knowledge, not least in the field of plant nursery techniques, propagating the larch hybrid 'Hrymur' with cuttings seems to be quite a viable possibility. Experiments reported in a new article published in the journal Rit Mógilsár, showed good rooting of both winter cuttings and unlignified summer cuttings of the hybrid. A promising potential is to cultivate the cuttings in microtrays and use robots for transplanting.

An english translation of the article title is "Propagating 'Hrymur' with cuttings". Author is Rakel J. Jónsdóttir, researcher and PhD student at the Icelandic Forest Research.

Front page of the 49th issue of Rit MógilsárDue to difficulties in seed production of the larch hybrid ‘Hrymur’ (Larix decidua x sukaczewii) supply of seedlings does not meet demand in Iceland. Therefore, vegetative propagation from cuttings during various times of the year was investigated in this project.

Based on the cultivation environment used, 60,7% and 67,1% rooting of winter cuttings was achieved. Lignified summer cuttings, with only lateral buds, rooted less (18,8% to 65%) than summer cuttings with little lignification and terminal buds (78,6% to 100%). Rooting was possible for cuttings of different lengths (6-8 cm, 5-7 cm, 3-4 cm and 2-2,5) in various times of the year. The main cause of mortality in the rooting phase was due to the growth of mould (Botrytis sp.).

The project revealed that cuttings of Hrymur need a minimum of 11 to 12 weeks of cultivation until satisfactory rooting is achieved. To be able to overwinter rooted cuttings in a cooler (at 2°C to 3°C) the photoperiod was gradually shortened along with temperature. By that, dormancy was induced in cuttings rooted in late autumn.

Of the three types of trays tested in the project, cultivation in microtrays proved to be the most interesting, due to easier transplanting of rooted cuttings, better efficiency and short production time of salable plants. The culture of mother plants, with respect to age, number of cuttings produced and the short growing season in Iceland, is essential for propagating Hrymur with cuttings in a profitable way. Continued research should therefore focus mostly on that aspect, according to the author.

The article is in Icelandic but with an english abstract.

Reporter: Pétur Halldórsson