Aspects regarding the propagation of Thuja occidentalis ’Columna’ using different rooting substrates

Ornamental trees planted inside the urban places: in gardens or in parks, around the buildings play an important role in ecology of human habitats.One of the most frecvently used ornamental conifer in Romania is Thuja occidentalis 'Columna', because it can be used in a wide variety of urban landscapes.This paper adresses the study of propagation of Thuja occidentalis 'Columna' using differente categories of rooting substrates.Choosing the ideal proportion and composition of rooting substrate is crucial in the propagation of Thuja occidentalis 'Columna'.Experiments were conducted at the "Mihai Viteazu" Nursery Garden from Turda, in spring 2013.The types and mixtures of rooting substrate used in the experimentwere: 100% peat (V1); 100% sand (V2); 50% peat + 50% perlite (V3); 50% peat +50% sand (V4); 50% sand + 50% perlite (V5).Peat was used to improve the rooting substrate structure and to increase water retention.Sand drains quickly and retains minerals efficiently.Horticultural perlite has the ability to absorb water and then releasing it over a long time due to its porous structure.In order to obtain more meaningful results we planted 450 cuttings, 90 in each substrate type.Statistical analysis of the influence of rooting substrate on the number of roots per cuttings showed significantly positive differences in substrate V5.Final results indicated that V5 substrate is the best for production by cuttings of Thuja occidentalis 'Columna'.Compared to the mean of experiment considered control the best V5 rooting substrate provided 100% rooting and 10.7 average numbers of roots per cuttings, with an average length 5.7 cm per cuttings after 18 weeks.