Autecology and survival of fathen (Chenopodium album L.)

Abstract

Between 1977 and 1980, a series of pot and field experiments were conducted to investigate the life history, seed survival rate and competitive ability of fathen against lucerne and peas. The life cycle of fathen is not bounded by specific temperature or photoperiod requirements. Under Lincoln conditions, it can behave as a spring, summer or even autumn annual, showing various kinds of plant structure and seed production, depending on the time of emergence. The polymorphic seeds of fathen influence its life cycle. Brown-smooth seeds have fast emergence rates and the plants grown from them are superior to plants grown from black-smooth seeds. Fathen is tolerant to both drought and water-logging, shows much pasticity under different densities, partitions a considerable proportion of its total weight into seeds with very large numbers being produced, and has an indeterminate growth habit. Fathen seed has a high emergence rate from the soil surface, but from below 40 mm depth there is little emergence. The seeds that do not germinate immediately, due to dormancy or greater burial depth, remain viable in the soil for at least 30 to 40, or even 46 years in soil (Chapter 1) and loss of viability takes place gradually. Thus, growing lucerne continuously for a long period of time would be an effective way of reducing number of viable fathen seeds. Fathen is competitive with lucerne, and when not controlled, can cause both lucerne mortality and dry matter reduction to the level of virtual extinction. By giving a topping treatment, however, both lucerne establishment and its dry matter can be increased. By regulating the date of planting (for example, sowing lucerne in August), infestation of fathen can be greatly reduced. Cutting or topping is also effective in reducing fathen but, due to the uneven emergence of fathen, it is difficult to recommend a specific cutting or topping time. High densities of peas of 92 plants m⁻² suppress fathen and MCPB is an effective chamical against fathen in pea crops. The results are discussed in relation to climate, growing conditions and cultivation practices.