Fecundity Allocation in Some European Weed Species Competing with Crops

Abstract

Seed production is an important element of weed population dynamics, and weed persistence relies upon the soil seed bank. In 2017 and 2018, we studied the relationship between the aboveground dry biomass of common weed species and their seed production. Weeds were selected randomly in the fields, and we surrounded the plants with a porous net to collect shed seeds during the growth season. Just before crop harvest, weeds were harvested, the plants’ dry weights were measured, and the number of seeds retained on the weeds was counted. A linear relationship between the biomass and the number of seeds produced was estimated. This relationship was not affected by year for Avena spica-venti, Chenopodium album, Galium aparine, or Persicaria maculosa. Therefore, the data of the two seasons were pooled and analysed together. For Alopecurus myosuroides, Anagallis arvensis, Capsella bursa-pastoris, Geranium molle, Polygonum aviculare, Silene noctiflora, Sonchus arvensis, Veronica persica, and Viola arvensis, the relationship varied significantly between the years. In 2017, the growing season was cold and wet, and the slope of the regression lines was less steep than in the dry season in 2018 for most species. Capsella bursa-pastoris was the most prolific seed producer with the steepest slope.