Main and Interaction Effects of Factors on Softwood Cutting of White Poplar (Populus alba L.).

White poplar is an important species for reforesting riparian sites in Algeria, but efficient techniques are still to be perfected. The study investigates the feasibility of softwood cutting as a method of propagation of the species. Results showed that sand or gravel, used as substrate, do not determine significant differences in rooting percent, but exert an influence on the quality and vigour of roots of cuttings. The findings, also, suggest that softwood cutting of the species would be most efficient if root suckers and/or sticklings were the sources of cuttings. Moreover, summer is the best period for achieving good results, while IBA treatments would have little effect on the rooting response of cuttings. Significant stand and individual within stand variation in rooting response of cuttings was found. However, the low or moderate broad sense heritabilities suggest that microsite effects at the individual scale could influence significantly the results. Overall, the results of the investigations suggest that selection of stands and, individuals within stands with good rooting ability, together with taking care with respect to factors such as the period of cuttings collection and the sources of cuttings, could achieve real progress in vegetative propagation of white poplar in Algeria.