Models that quantify the effects of cropping systems on weed dynamics are useful tools for testing innovative cropping systems. In these models, seed mortality in the soil is a key parameter to account for the cumulated effect of cropping systems over time via the soil seed-bank. Since seed mortality is difficult to measure, our objective was to develop a method to estimate it from easily accessible information. Seeds of 13 weed species were buried 30cm deep in fields and were recovered regularly for 2 years to measure their viability. Seed mass, dimensions, shape, and protein and lipid contents as well as coat thickness were measured. To estimate seed mortality of species not included in the study, we searched for relationships between mortality rates and seed traits. Seed viability mainly decreased during the second year of burial, with mortality rates ranging from 0.01 to 0.63 seeds.seeds(-1).year 21, depending on the species. Seed mortality decreased with increasing seed coat thickness. No correlation was found with other measured traits or with seed persistence data in the literature. These results were confirmed when the effects of phylogenetic relatedness with phylogenetically independent contrasts were included. The thickness of the seed coat, which varied between 17 and 231 mm over the range of species studied, can protect the seed from external attacks in the soil and slow down seed decay. This trait can be easily measured via X-ray images and could be used to estimate the seed mortality rate for a wider range of species

International audienc

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Integrating principles of ecological intensification into weed management strategies requires an understanding of the many relationships among weeds, crops and other organisms of agro-ecosystems in a changing context. Extensively used during the last two decades in weed science, trait-based approaches have provided general insights into weed community response to agricultural practices, and recently to understanding the effect of weeds on agro-ecosystem functioning. In this review, we provide a holistic synthesis of the current knowledge on weed response and effect functional traits. Based on the literature and recent advances in weed science, we review current knowledge on (i) weed functional groups and ecological strategies, (ii) weed functional response traits to cropping systems and (iii) weed functional effect traits affecting agro-ecosystem functioning. For each functional trait, we explicitly present the assumptions and evidence on the linkage between trait values and ecological functions, in response to either management practices, for example tillage, sowing and herbicides, or biotic interactions, for example crop-weed competition and pollination. Finally, we address and discuss major research avenues that may significantly improve the use of traits and the knowledge of functional diversity in weed science for the future, especially to design and implement more environmentally sustainable weed management strategies.