Studies on the soil seed bank of the environmental weed Rumex vesicarius (Fam.: Polygonaceae) at a rehabilitated mine site in semi-arid Western Australia

Abstract

Long-term control of the weed Rumex vesicarius (Fam.: Polygonaceae) (common name: Ruby Dock) in rehabilitated mine sites in semi-arid areas of Western Australia requires knowledge of the total size of the seed bank and its properties (longevity and germination of the seeds). Ruby Dock seeds are polymorphic (light and dark of various colour shades) and of high potential viability. At the Plutonic mine site near Meekatharra (Western Australia) areas heavily infested with Ruby Dock were characterised by large numbers of fruits, which contained numerous viable, dark seeds. Intact, light seeds were found in only a small percentage of the recovered fruits. Experiments in the greenhouse demonstrate that a large number of potentially viable Ruby Dock seeds remained in the soil after three germination seasons. A high proportion of the seeds, which germinated produced seedlings during the first germination season, soon after watering commenced. The application of herbicides at seedling stage, removal of fruit mats (which consist of large numbers of fruits intermingled with decaying plant material from previous seasons) and increase in competition through native plants currently appear to be the most efficient measures to control the size of the seed bank in rehabilitated mine sites.