Light availability experienced in the field affects ability of following generations to respond to shading in an annual grassland plant

For plants competing for light, grasslands represent complex environments. Grassland microhabitats vary in the amount of available light and in the spatial distribution of patches with full sunlight, light shade and deep shade. Plant populations have been shown to adapt to specific competitors and shading conditions, but it is an open question how tightly the responses of populations to different shading situations are linked to the light availability previously experienced in the field.
Using maternal families collected in grasslands ranging from open to closed canopies, I tested the effects of no shading, homogeneous and heterogeneous shade created in the glasshouse on trait expression in the annual Erodium cicutarium. Heterogeneous shading was simulated by a patchwork of single and double layers of light filters lowering the R:FR ratio of transmitted light and clear filters simulating gaps.
Heterogeneous shading induced a stronger shade avoidance response than homogeneous shading, ...