Assessing potential germination period of weeds with base temperatures and base water potentials

Seed germination partly depends on both base temperature (Tb) and base water potential (Ψb), which currently are known only for a small number of species. Laboratory experiments were conducted to estimate these parameters for 14 weed species using the ‘x‐intercept’ method. Tb and Ψb (°C and MPa) for the 14 weed species were as follows: Amaranthus retroflexus (8.9 and −0.95), Ambrosia artemisiifolia (3.6 and −1.28), Avena fatua (2.2 and −1.02), Capsella bursa‐pastoris (4.5 and −0.95), Chenopodium album (5.9 and −0.80), Echinochloa crus‐galli (6.2 and −1.19), Geranium dissectum (0.6 and −3.31), Matricaria perforata (2.0 and −0.75), Picris echioides (5.2 and −0.79), Polygonum lapathifolium (5.8 and −1.55), Senecio vulgaris (2.5 and −1.23), Setaria pumila (8.6 and −0.75), Solanum nigrum (11.6 and −0.89) and Veronica hederifolia (0.2 and −1.67). The two parameters were used to determine potential germination times during expected non‐dormancy periods for three contrasting climatic years in Dijon, France. The number of potential germination days varied little among the tested climatic years, but substantially among species, ranging from 95 ± 9 days for V. hederifolia to 280 ± 7 days for M. perforata. These results may be of value for development of predictive growth models and understanding times when weed control may be most feasible.