The effects of temperature on germination and early growth of three plant species indigenous to Central Australia

The temperature responses of the perennial grass Eragrostis eriopoda Benth., an all‐season annual grass (Enneapogon polyphyllus Domin.) and a cool‐season annual forb (Lepidium muelleri‐ferdinandi Thell.) were studied in two experiments, one during germination and the other during the establishment phase. In the first experiment, extreme differences in the response of germination to temperature occurred between species. The optimum was 42°C for Eragrostis and 15 to 21° C for Enneapogon and Lepidium although Enneapogon tolerated higher temperatures than did Lepidium. The effect of temperature on speed of germination is discussed. In the second experiment, seedlings were assigned to six day/night temperature regimes ranging from 24/16 C to 45/31 C for three weeks in a phytotron. Both grasses responded positively to temperatures tip to 30/22°C with little further change up to 45/37° C, while Lepidium died at temperatures greater than 30/22° C. The experimentally determined response to temperature reflected field observations of seasonal establishment patterns for each species. The ecological significance of the results is discussed.