Seed Germination and Root‐Sprout Requirements of Ailanthus altissima (Mill.) Swingle

Tree of heaven ( Ailanthus altissima ) is a worldwide invasive species characterised by its high capacity of reproduction. Knowledge of the environmental requirements for reproduction is essential for developing successful management programs. Seeds and roots of different diameters of A. altissima were collected from natural populations in autumn and stored at environmental conditions. A portion of seeds were treated in order to determine the best technique to break dormancy. Once the best technique was found, different temperatures (10°C, 14°C, 17°C, 22°C, 25°C and 28°C) and water potentials (0, −0.1, −0.2, −0.4 and −0.6 MPa) were applied to estimate base temperature and base water potential. Viability of seeds from trees previously treated with glyphosate injected into the trunk were also tested. Roots from the same population were collected and cut at different lengths and its base temperature and sprouting rate were estimated. Cold stratification of seeds at 10°C for 21 days provided the best results for break dormancy. The base temperature of seeds and roots was 9.6°C and 9°C respectively. The seed base water potential was estimated at −0.74 MPa. Seeds from trees treated with glyphosate did not show any reduction in their viability. The minimum root fragment capable of sprouting was 4 cm long and 3–4 mm in diameter. The Gompertz model provided the best fit for seed emergence, whereas the Weibull model was the best fit for the sprouting of the root fragments.