UNTERSUCHUNGEN ZUR BIOLOGIE UND ÖKOLOGIE DER HÜHNER‐HIRSE ECHWOCHLOA CRUS‐GALLI L. BEAUV.

Summary. 1. Echinochloa crus‐galli is a typical grass weed of root crops in warmer regions, germinating late and thus covering the soil at a late stage. It originates in central and east Asia and is now a weed of world‐wide importance. 2. High temperatures are necessary for germination which begins in spring, but not before the soil temperature reaches 15° C. Minimum, optimum and maximum germination temperatures of 13° C, 20–30° C and 40° C were found in S.W. Germany. 3. Seeds of E. crus‐galli are dormant during the first 3–4 months after harvest. Those developing relatively early in the growing season require rather longer for after‐ripening than seeds which mature later. 4. For optimum germination, water saturation of the soil of 70–90% is required. 5. Soil acidity has some influence, and there is an apparent germination optimum around neutrality. Light also induces germination. 6. Seeds can emerge from a relatively wide range of depths. Greatest emergence and the strongest plants resulted from seeds at 2–6 cm, but even from 10 cm a high percentage of seedlings is likely to emerge. 7. Further development proceeds rapidly. The first panicles arc already formed 6–7 weeks after emergence in favourable conditions, but full maturity is possible only if there are high temperatures in late summer. 8. E. crus‐galli is a hygrophilous species, with best development on medium heavy soil, sandy loam or loamy sand with sufficient water supply. 9. E. crus‐galli is indifferent to the lime content of the soil. 10. Best development occurs with high fertility, and a rich supply of nitrogen is especially important. Recherches sur la biologie et écologie du panic Echinochloa crus‐galli (L.) Beauv.