VEGETATIVE PROPAGATION VIA CUTTINGS OF THE MOROCCAN EUPHRATES POPLAR (Populus euphratica Oliv.) IN THE CONTEXT OF CLIMATE CHANGE

Euphrates poplar (Populus euphratica Olivier) extends over a very wide range from China to North Africa. In Morocco, it covers very small areas subject to very severe environmental stresses (aridity, salinity, heat). Vegetative propagation techniques easy to implement by nursery workers are not well documented in Morocco. The objective of this study is to develop an operational technique by cuttings. Dormant and lignified sets (length: 50 to 80 cm, diameter: 8.72 ±2.12 mm) sampled from Ait Atmane population, located between Er-Riche and Er-Rachidia in the south-central region from Morocco. The hormonal effect of indole butyric acid (IBA) at 1% and that of the growing medium were evaluated on sets rooting according to a factorial experimental design.

Rooting rate of living sets, after 2.5 months of culture, varied between 92.5 and 100%, with no significant effect of the growing medium and hormonal treatment. Hormonal treatment significantly improved the number of roots per set. It varied between 25.5 and 23.9 with hormone treatment, against 14.0 and 16.7 roots with none. Organic growing medium significantly improved root development. Rate of long and short root sets is significantly higher on organic growing medium with 55.4% and 65.8%, respectively, versus 23.7% and 37.8% on mineral growing medium, respectively. However, 18.4% of the sets showed necrosis at their bases after hormone treatment. Mortality was 52.5% in IBA-treated sets grown on mineral growing medium compared to only 5.3% on organic growing medium. Mortality rate of non-IBA treated sets did not exceed 1.3% on both types of growing medium. Rate of bud burst of live sets varied significantly between 80.3 and 98.8%, slightly higher without hormone treatment.

Cuttings of Euphrates poplar can be undertaken to enhance this species in marginal areas in the context of climate change. However, clonal variability exploration is necessary to select efficient and tolerant clones to environmental stresses.