A novel approach for the operational production of hybrid larch seeds under northern climatic conditions

Abstract

Hybrid larch ([Larix ϫ marschlinsii Coaz], HL) is sought after by the forest industry because of its growth characteristics, excellent wood quality and disease resistance. However, the difficulty in obtaining HL seeds limits the production of seedlings for reforestation. Both European larch (Larix decidua Mill.) and Japanese larch (Larix kaempferi [Lamb.] Carrière) produce few seeds and the time lag in their flowering phenology complicates their natural pollination. We have developed a novel type of sheltered seed orchard, dedicated to the production of HL seeds from grafts grown in pots. Inverting the arches of a conventional tunnel provides a sturdy structure which is easy to maintain. Because of its height, the tunnel can accommodate the rapid growth of the trees, which reduces the need for pruning. The tunnels are covered in the winter and spring. In the winter, the covers prevent snow accumulation. In the spring, they create a "greenhouse effect" inside the tunnels, accelerating flower development, preventing pollen contamination from trees outside the tunnels and protecting the flowers from late spring frosts. Over the past five years, flowering has been regular and abundant. Bagging the crowns for pollen harvest is cost-effective and yields large quantities of high quality pollen. Pollination operations are conducted using an electrostatic pistol. Because of the large number of available clones, large quantities of seeds with a high genetic variability can be produced at a competitive cost. In 2006, this seed orchard concept was implemented operationally at the Berthier forest nursery (Québec, Canada).

Composition of hybrid larch (Larix × eurolepis Henry) forest reproductive materials: How much does hybrid percentage affect stand performance?

“…Verify that the site is well-isolated from incoming pollen Prefer tree by tree alternation of species Consider establishing indoor-orchards in northern countries (Colas et al 2008) and take measures to reduce epigenetic effects…”

Living without herbicides in Québec (Canada): historical context, current strategy, research and challenges in forest vegetation management

“…Lamhamedi et al 2001Lamhamedi et al , 2006. Other recent developments include the design of operational sheltered seed orchards adapted to hybrid larch (Larix 9 marschlinsii Coaz) production in northern conditions (Colas et al 2008b). The gradual shift from bare root seedling production towards containerised production, initiated in the 1980s, was continued in the 1990s.…”

Rates of spontaneous hybridization and hybrid recruitment in co-existing exotic and native mature larch populations

“…Carr., and Larix sibirica Ledeb.) and their hybrids have been introduced into North America for use in plantations to alleviate harvesting pressure on natural forests (Dumoulin 1999;Colas et al 2008). As for other conifers, reproductive barriers between larch species are generally weak and hybrids are easily produced (Baltunis et al 1998;Acheré et al 2004;Colas et al 2008;Moriguchi et al 2008).…”

“…and their hybrids have been introduced into North America for use in plantations to alleviate harvesting pressure on natural forests (Dumoulin 1999;Colas et al 2008). As for other conifers, reproductive barriers between larch species are generally weak and hybrids are easily produced (Baltunis et al 1998;Acheré et al 2004;Colas et al 2008;Moriguchi et al 2008). Hybrid larches are widely used in forestry because of their faster growth, higher volume, and increased resistance to insects and diseases (Eko et al 2004;Perron 2008;Pâques 2009).…”

“…Given the weak reproductive barriers, there is the possibility that populations of native larch found in eastern Canada, such as tamaracks (Larix laricina (Du Roi) K. Koch), hybridize spontaneously with exotic Eurasian species within plantations. Several studies (Häcker and Bergmann 1991;Colas et al 2008;Pâques 2009) have already looked at the production of hybrid seeds in mixed plantations of L. decidua and L. kaempferi. However, little is known about spontaneous hybridization between these Eurasian larches and native L. laricina, and whether hybrid seeds are viable and capable of establishing.…”