Seed mortality in the soil is related to seed coat thickness

Abstract

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

Weed seed survival in experimental mini-silos of corn and alfalfa

“…3). This could be related to seed coat thickness, a feature that we did not measure but was related to survival in soil (Gardarin et al 2010). However, seed viability after one month of storage in corn or alfalfa silage was not related to average specific seed impermeability (p > 0.05) (Fig.…”

“…In species with physical dormancy, seed survival in silage has been found to be positively related to the proportion of seeds that were still hard after three weeks in water (Westerman et al 2012), as impermeable coats protect the embryo from harsh environmental conditions (Mohamed-Yasseen et al 1994). Seed survival in the soil has also been partially related to seed coat thickness (Gardarin et al 2010), a feature that will protect from moisture variations. However, other structural features (e.g., the strophiole) can enhance seed permeability (Kelly et al 1992).…”

Skylarks trade size and energy content in weed seeds to maximize total ingested lipid biomass

“…For instance, the relative strengths of the seeds was found to be negatively correlated with seed size (Lundgren and Rosentrater, 2007), suggesting that smaller seeds require a greater force and energy to crush them. It would be interesting in further studies to take into account other morphological seed traits even though the relationship between seed traits such as size, nutrient composition, secondary compounds or digestibility is often complex and nonlinear (Gardarin et al, 2010;Blate et al, 1998;Shimada, 2001). Artificial seeds could enable to tease apart the relative influence of different seed traits (see for example, Wang and Chen, 2012).…”

Which cropping systems to reconcile weed-related biodiversity and crop production in arable crops? An approach with simulation-based indicators

“…b Class of importance of the different weed species in the diet of farmland bird was determined after Wilson et al (1999), and completed after Marshall et al (2003). c Seed lipid content of weed species (Gardarin et al, 2010) was used as a proxy of specific preferences of seed-eating carabids, after the observations of Trichard et al (unpublished). d Pollination values of the different weed species for domestic honey bees were determined after Ricou et al (2014).…”

“…Because weed seeds survive over several years (Gardarin et al, 2010), crop management techniques affect weed dynamics over several years (Liebman and Ohno, 1998;Doucet et al, 1999;Bond and Grundy, 2001;Koocheki et al, 2009;.…”