Data from: The roles of interspecific variability in seed mass and soil resource availability in root system development

Aims Because plant roots serve mainly as organs for the uptake of water
and nutrients, we aimed to test whether the development of seedling roots
is influenced by the two principal nutrient sources—the substrate and the
pool stored in the seed itself. Methods Using seven Fabaceae species that
differ in seed mass, we observed their early root system development under
four levels of nutrient availability. Transparent-wall rhizoboxes allowed
us to track root development and to score root system structure (length
and number of roots), size (depth and width of root system) and shape
(relative depth and width of root system). Results Seedling root system
development depended on both the amount of nutrients contained in the
substrate and on the seed mass of the species. Compared to an average
seedling, effects of these two nutrient pools were (i) opposite and (ii)
did not fully overlap. Small-seeded species developed wider root systems
that branched earlier than large-seeded species. Increased availability of
nutrients in the substrate led to proliferation of lateral roots, without
any substantial impacts on the shape of root system or beginning of
branching. Conclusions The source of the nutrients affected the way they
were used throughout early root system development, leading to different
structures and dynamics. This may be one of the mechanistic links
connecting seed mass and the realized niche of the species.