Germination ecology of Chenopodium album L. and implications for weed management

Chenopodium album L. is a troublesome annual species in various cropping systems, and a sound knowledge of the ecological response of C. album germination to environmental factors would suggest suitable management strategies for inhibiting its spread. Preliminary laboratory-based research was conducted to investigate germination and emergence requirements of C. album under various environmental conditions (e.g., photoperiods, constant temperature, salinity, moisture, soil pH, burial depth, and oat crop residue). Results showed C. album seeds were found to be photoblastic, with only 13% germination in darkness. The maximum germination (94%) of C. album occurred at an optimal temperature of 25°C, and the depressive effect of other temperatures on germination was more severe at lower rather than higher temperatures. Seed germination was suitably tolerant of salinity and osmotic potential, with germination observed at 200 mM NaCl (37.0%) and -0.8 MPa (20%), respectively. Germination was relatively uniform (88-92%) at pH levels ranging from 4 to 10. The maximum germination of C. album was observed on the soil surface, with no or rare emergence of seeds at a burial depth of 2 cm or under 7000 kg ha.sup.-1 oat straw cover, respectively. Information provided by this study will help to develop more sustainable and effective integrated weed management strategies for the control of C. album, including (i) a shallow-tillage procedures to bury weed seeds in conventional-tillage systems and (ii) oat residue retention or coverage on the soil surface in no-tillage systems.