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ŠUMARSKI LIST 9-10/2021 str. 62     <-- 62 -->        PDF

Spach), and was first found in Leighton park in Wales, where these two species are found (Lindstrom et al., 1997). The species is very popular in the United Kingdom and the European continent, therefore, it can frequently have seen as an ornamental tree in parks and gardens as well as in windbreaks (Blythe, 1989). Leyland cypress which can tolerate various habitat conditions, is a rapidly-growing evergreen tree when young, even on poor soils, and, ultimately, reaching 30 m in height (Lindstrom et al., 1997). The existence of the problems (heterozygosity, infertile seeds and etc.) encountered in the generative propagation of these species, which are of high importance as ornamental plants, reveals the necessity to try different production techniques. In addition, since these species are frequently used in landscape works, parks and gardens, the production of these species in the desired form and quality can be achieved by vegetative propagation. Hence, it is necessary to investigate the vegetative propagation methods of these species for sustainable use.
Because the effectiveness of nursery management is seriously affected by delay in germination, alternative planting materials are required (Akinyele, 2010). Vegetative propagation method might be an excellent alternative for plant production, especially for species that have seminal propagation limitations (Oliveira and Ribeiro, 2013), because of the advantages such as planting uniformity, higher productivity, lower costs, and, above all, year-round plantlet production (Wendling et al., 2016). Vegetative propagation of plants by stem cuttings is one of the most common used to produce new plants. Stem cuttings can be classified as four groups to be hardwood, semi-hardwood, softwood and herbaceous (Hartmann et al., 2002). The method is considered one of the most important plant propagation technique since it is economically viable, simple and fast (Stuepp et al., 2018). There are a lot of factors that can affect the rooting potential of stem cuttings. The induction of roots is a process regulated by environmental and endogenous factors such as plant species, maturity, time of year, specific cultivar needs, the source, position, and type of cutting taken, juvenility and condition of stock plant, wounding or leaf removal, bottom heat, temperature, light, plant growth regulators (especially auxin), carbohydrates, mineral salts and other molecules (Hartmann et al., 2002; Gehlot et al., 2014).
Although plants naturally have the necessary substances for root and shoot formation in the vegetative propagation method (Hartmann et al., 2002), most plants require specific chemicals (growth regulators, mineral components, etc.) for the initiation of cell differentiation and root meristem formation (Erst et. al., 2018). Auxins, one of the plant growth regulator, are efficient inducers of adventitious roots in many woody species (De Klerk et al., 1999). They control growth and development including main root formation, lateral and adventitious root initiation (Stoeckle et al., 2018; Guan et al., 2019). IBA (indole-3-butyric acid), IAA (indole-3-acetic acid) and NAA (α-naphthalene acetic acid) can be stated as the widely used sources of auxins for rooting of cuttings (Fogaça and Fett-Neto 2005). Moreover, Singh et al. (2018) reported that IBA and NAA are still the most widely used auxins for rooting stem cuttings. On the other hand, rooting medium is one of the most important factors for rooting status in cutting propagation (Abebe, 2017; Singh and Chauhan, 2020). In addition, Galavi et al. (2013) reported that good growth medium provides a reservoir for plant nutrients, hold plant available water, and provide a means for gas exchange and good anchorage for the plants. In cutting propagation, perlite and peat are the most commonly used rooting medium. Perlite, which is mostly used by growers as rooting substrates, has moisture retention and good aeration characteristics, sterility and light weight (Hartmann et al., 2002). On the other hand, peat is an organic material generally used in greenhouse cultivation, floriculture, seedling production and similar horticultural works all over the world (Çolak and Günay, 2011). The hypothesis of the study is that there are differences in terms of different greenhouse medium, rooting medium and hormones on propagation by hardwood cuttings of Chamaecyparis lawsoniana ‘Ellwoodii’, Cryptomeria japonica ‘Elegans’ and x Cupressocyparis leylandii. Thanks to discover the optimum propagation conditions, the study can guide producers in the process of these taxa’s production.
2. MATERIAL AND METHOD
2. MATERIJALI I METODE
Hardwood cuttings taken on March 10, 2016 from the last annual shoots of Chamaecyparis lawsoniana ‘Ellwoodii’, Cryptomeria japonica ‘Elegans’ and x Cupressocyparis leylandii stock plants located in Karadeniz Technical University (KTU) Kanuni Campus were used as study material in the present study that was conducted in The Research and Application Greenhouse at Faculty of Forestry, KTU. Cutting materials were obtained from single stock plants of 30 years old for each taxon in order to eliminate genetic variation.
This study was carried out in three greenhouse medium with different conditions using perlite and peat rooting medium. These are Greenhouse-1 medium (GM-1; air temperature at 20±2°C, rooting table temperature at 20±2°C), Greenhouse-2 medium (GM-2; air temperature at 20±2°C, rooting table temperature at 25±2°C) with technological systems, where temperatures are adjusted with an automation system, and Greenhouse-3 medium (GM-3) that is nylon tunnel greenhouse medium without temperature adjustment. Since no temperature regulation was made in Greenhouse-3 medium, the temperature