Factors affecting seed germination and emergence of button grass (Dactyloctenium radulans) (R.Br.) P.Beauv.

Button grass (Dactyloctenium radulans) is a native, widely spread summer grass weed species in Australia. However, limited information is available on seed germination biology of this species. Experiments were conducted to evaluate the effect of environmental factors on the germination and emergence of two populations of D. radulans. The seeds of these populations were collected separately from Dalby, Queensland and Coleambally, NSW. Seeds were germinated at a range of constant and alternating temperatures (25/15, 30/20, 35/25, and 40/30 oC day/night). The greatest seed germination was at a constant temperature of 30 oC. Seed germination was reduced at the lowest alternating temperature (25/15 oC). Germination of both populations was strongly stimulated by light, suggesting a great amount of emergence of D. radulans on bare ground such as crop seedbeds. Germination of the D. radulans population collected from a northern cotton farming system (Dalby) was more tolerant to a greater range of salt stress than the population sourced from the south. Seeds of both populations germinated over a wide range of pH, between 4 and 10. However, germination was greatest in a high pH buffer solution indicating the species prefersto germinate in alkaline soil. These results showed that D. radulans seeds possess a wide range of tolerance mechanisms to different environmental stresses. Information gained in this study will help in developing more sustainable and effective integrated weed management strategies for the control of this weed and weeds with similar responses in summer cropping systems such as cotton.