Rumex crispus L. seeds were buried at 1 and 10 cm depth in the soil and retrieved at regular intervals during two years. Retrieved seeds were tested at 10o and 20o in darkness; at 5/25oC (16/8 hours) with 10 mM potassium nitrate and light; and at an alternating temperature regime corresponding to the minimum and maximum soil temperatures (MMTS) at a depth of 1 cm during the six days prior to each retrieval. MMTS treatments were carried out in darkness with either 1 mM potassium nitrate or a cocktail of dormancy relieving chemicals consisting of potassium nitrate, thiourea, ethephon, sodium azide and hydrogen peroxide. There was no appreciable loss of seed viability in the soil during the study period. The seeds showed dormancy cycles in the soil throughout the year, where low soil temperatures relieved primary dormancy and induced secondary dormancy, which in turn was relieved by high temperatures. There was a year-to-year reduction in seed dormancy. The environment at 10 cm favoured loss of dormancy, however the depletion due to in situ germination was faster at 1 cm. The chemical mixture was more effective when dormancy was minimal and the soil temperatures were more promotive, which coincided to the warm period of the year (from spring to autumn). These results are discussed in terms of the interpretation of the ecological behaviour of this species in the field and the adoption of practices of management of seed banks in the soil.
control; depletion; dock; stimulants