Nursery rooting and growth of Norway spruce cuttings

Norway spruce (Picea abies) is an economically important species for the production of Christmas trees in north and central Italy. Therefore, there is an interest in tree improvement and clonal propagation to produce plants which reach specific standards. This study describes the rooting response and subsequent growth characteristics of norway spruce cuttings from 5 and 10-year-old plants. Tips of primary axes were collected in October 2004 (semi-hardwood), March (hardwood) and June (softwood) 2005. IBA at 0, 19.6, or 39.2 mM in 50% percent ethanol were tested for root induction. The bases of cuttings were dipped in a treatment solution for few seconds, potted in perlite, and placed in a mist bed for 16 weeks. Rooted cuttings were gradually hardened off from the mist bed. Data included: rooting percentage, number of primary roots, total root lengths and linear growth of the rooted cuttings at different time. Cuttings from 10-year-old plants failed to root. Rooting percentage of 5-year-old cuttings for the entire study tended to be low, 30 % and 10% for October and March, respectively. Rooting in the June trial was quite poor. Further, semi-hardwood cuttings produced the 3.3 roots with the 14.2 cm total root length, these values were significantly higher than those of hardwood cuttings, 2.1 and 9.5 cm, respectively. The percentages of the rooted cuttings exhibiting orthotropic growth increased from 51% to 69 % in the second year, whereas those of the rooted cuttings exhibiting plagiotropic growth decreased from 30% to 17%. The height of rooted cuttings increased significantly from the first to third year; semi-hardwood cuttings always had better growth. In this study, growth stage of the donor plants significantly affect some rooting traits such as production and total length that could translate into better performance upon outplanting. Further researches need to improve rooting and understand what effect root system quality plays in long-term growth.