Dry matter production and partitioning of Chenopodium album in contrasting competitive environments

Abstract

Simple models were developed to quantitatively describe (a) dry matter production and (b) the effects of competition on dry matter partitioning of Chenopodium album L. Data on total biomass and its allocation to roots, stems and leaves were obtained from field experiments with C. album planted at two densities in pure and mixed stands with either cauliflower (Brassica oleracea L. convar. botrytis var. botrytis) or faba beans (Vicia faba L.). After germination, C. album produced biomass rapidly; weeds planted at low density accumulated 20–30% less dry matter than plants growing at a 2.5‐fold higher density per m2. A close correlation between the transmission of photosynthetically active radiation (PAR) and leaf area index was found. Biomass production was linearly related to cumulative PAR intercepted, but a seasonal variation of the radiation‐use efficiency could not entirely be explained. The root:shoot ratio was constant, whereas the level of competitive stress changed the distribution pattern between stems and leaves. With increasing competition in the cauliflower experiments, C. album allocated relatively more biomass to stems than to leaves; this was less evident in mixtures with faba beans. In field vegetable production with an abundant water and nutrient supply, the growth processes of C. album may be described quantitatively using simple functional relationships.