Temperatures during storage, light and wetting affecting caryopses germinability ofSchismus arabicus, a common desert annual grass

The common desert annual grassSchismus arabicusproduces many tiny caryopses which germinate only after dry storage at high summer temperatures. Two years after maturation, 24% germinated within 22 h in dark at 20°C. At 20°C and in low light, there was less germination than in dark, although not at 25°C and 30°C. The lower the temperature, within the range 5–15°C, the longer the delay in the start of germination and the lower the levels of germination in light and dark. In alternating summer temperatures of 18h at 20°C and 6 h at 40°C, the percentage of germination was higher (53%) than in winter temperatures of 18 h at 15°C and 6 h at 5°C (40%). The ecological importance of germination regulated by post-maturation dry storage duration and temperatures, and temperatures during wetting, under light or dark, is discussed.