Unlocking dormancy and gemination ecology of prostrate knotweed (Polygonum aviculare) in eastern Australia

A series of laboratory experiments was conducted to break seed dormancy and to investigate the germination ecology of prostrate knotweed ( Polygonum aviculare L.) populations for designing weed management practices in eastern Australia. Foundational studies identified sodium hypochlorite (NaOCl) immersion of seeds for 8 hours as the most effective method for breaking seed dormancy and enhancing germination. Therefore, in the subsequent seed germination ecology experiments, seeds treated with NaOCl for 8 hours followed by a 10-minute water rinse were used, and two populations (Gatton and Nangwee) were selected for the studies. The Gatton population exhibited higher germination than the Nangwee population at alternating day/night temperatures ranging from 15/5 to 30/20 C. Germination in both populations did not vary at day/night temperatures ranging from 20/10 C to 30/20 C. Therefore, considering P. aviculare as a winter season weed in Australia, an optimal temperature of 20/10 C was selected for further light/dark, salt and osmotic stress, residue cover, and burial depth studies. Averaged over populations, germination of P. aviculare peaked at 92% under alternating light/dark conditions but declined to 49% in complete darkness, confirming the species’ positive photoblastic nature. Under stress (salt and osmotic) conditions, the Gatton population maintained ∼50% germination at 250 mM NaCl and –0.8 MPa osmotic potential and showed higher tolerance to these stresses than the Nangwee population. Moderate residue cover (2–4 Mg ha⁻¹) enhanced seedling emergence (up to 58% in Nangwee and 36% in Gatton populations), likely due to improved surface moisture and partial light availability. However, seed burial beyond 4 cm nearly eliminated emergence due to light exclusion and mechanical resistance. These findings suggest that P. aviculare is well adapted to surface soil conditions and may thrive in reduced-tillage, residue-retained systems. Strategic deep tillage and surface-targeted herbicides are essential for effective management of this light-sensitive, residue-adapted weed.