Effets non compétitifs entre le chénopode blanc (Chenopodium album L.) et le mais (INRA 258)

Summary: Non‐competitive effects between lamb's quarters (Chenopodium album L.) and maize (INRA 25H) Maize is extremely sensitive to competition from weeds, lamb's quarters (C.alhum) often being particularly competitive, Under controlled conditions in a growth chamber short term bioassay methods techniques have shown that lamb's quarters exerted inhibiting influences on maize growth which were not attributable to competition alone. These non‐compctitive, specific influences became apparent mainly from the early flowering stage of lamb's quarters both in soil and in nutrient solution. With an identical concentration of lamb's quarters roots, the growth‐inhibiting effects are more marked when the soil structure is modified than when it is not, similarly when the aqueous extract is obtained by placing soils in suspension, the inhibiting effects are more marked than when it is obtained by percolation. Finally, water leached from the leaves, roots or seeds of lamb's quaners shows inhibiting effects proport ional to the concentration on root growth of maize. The presence of phytotoxins in the culture media of lamb's quarters is discussed.