Effects of environmental factors on seed germination and seedling emergence in three Alopecurus weeds

Alopecurus aequalis, A. japonicas, and A. myosuroides are malignant weeds in farmlands; however, the factors affecting seed germination and seedling emergence in these weeds remain poorly understood. Therefore, the main objective of this study was to clarify the effects of temperature, salt stress, osmotic stress, and planting depth on Alopecurus germination and seedling emergence. A Petri dish method was used to evaluate the effects of temperature, salt stress, and osmotic stress on germination, and a pot method was used to evaluate the effects of burial depth on seedling emergence. The seeds of A. japonicas and A. myosuroides germinated at constant temperatures of 5～30 ℃, fluctuating day/night temperatures 5 ℃/15 ℃～25 ℃/35 ℃, and NaCl concentrations 0～300 mmol·L⁻¹, whereas A. aequalis seeds only germinated at constant temperatures 5～20 ℃, fluctuating temperatures 5 ℃/15 ℃～20 ℃/30 ℃, and NaCl concentrations 0～200 mmol·L⁻¹. The three Alopecurus weeds showed no germination at an osmotic potential greater than –1.0 MPa. The burial depths for 50% inhibition of the maximum germination of A. aequalis, A. japonicas, and A. myosuroides were 2.27 cm, 9.26 cm, and 8.17 cm, respectively. This suggests that the seedling emergence abilities of A. japonicas and A. myosuroides were stronger than those of A. aequalis. Overall, the results of this study suggest that all three Alopecurus weeds germinate and emerge under a wide range of environmental conditions. The information from the present study can be used to predict future infestations in China and help develop strategies to manage these weeds. Integrated control measures need to be implemented for preventing the spread and control of these weeds in the future.