The influence of Naphthalene Acetic Acid (NAA) in rooting of the different vegetative cuttings of Thuya occidentalis “emeraud”

Thuya occidentalis “Emeraud” (Thuya ssp), is one of the most used evergreen ornamental plants for decoration of parks and gardens with very slow growth. They form few seeds with relatively low germination. This is the cause of the continuous efforts to find efficient ways of vegetative propagation, which influence the increase of the coefficient of thuya’s propagation. The paper presents the influence of the naphthalene acetic acid (NAA) 4000 ppm in the rooting of one year vegetative cuttings of Thuya occidentalis “Emeraud”, with and without biennial wood. The experiment was carried out during three consecutive years, 2008-2010, in the flower’s greenhouse of the Experimental Centre of the Department of Horticulture at Agricultural University of Tirana. The one year vegetative cuttings were prepared as simple cuttings (cuttings without bark or biennial wood) and cuttings with the scion (cuttings with bark or biennial wood). Vegetative cuttings of thuya were sown in the perlite band. Control for the final rooted seedlings and/or rooting percentage was carried out 60 days after sowing of the vegetative cuttings in the perlite band. There was calculated the rooting percentage of the vegetative cuttings treated and untreated with NAA 4000 ppm. The results show that the average rooting percentage of the simple untreated cuttings was 20%, while the average rooting percentage of the untreated cuttings with a scion was 45%. Total rooting percentage of the untreated cuttings was 32.5%. So, cuttings with a scion (the cuttings with bark and biennial wood), have a higher rooting percentage even when they are not treated with NAA. There were observed significant differences of the results in the case of treating cuttings with the rooting hormone NAA, 4000 ppm. These differences consisted in increasing the rooting ability and the rooting percentage of the cuttings. The average rooting percentage of the simple untreated cuttings with NAA was 51%, while the mean percentage of the cuttings with a scion treated with NAA was 80%. The total rooting percentage of the untreated cuttings was 65.5%. The use of the rooting hormone NAA, 4000 ppm, for the treatment of the one year vegetative cuttings of thuya was followed by the significant increases the rooting percentage in total from 32.5% to 65.5%. The three-year-results showed that the use of the rooting hormone NAA, 4000 ppm, does affect significantly in the increase of the rooting percentage of the vegetative cuttings, up to 30%, as well as in doubling the quantity of the seedling produced for each planting season, which was confirmed by ANOVA.