Adjustment of height growth to the speed of height increase of artificial light gradients in the stoloniferous plant Potentilla reptans

Plants in herbaceous vegetation stands experience a changing light environment, as density and height increase during the season. Many plants continuously adjust the height at which their leaves are deployed in order to prevent shading. Here we present an experimental set up that mimics such a setting. Shoots of five genotypes of the stoloniferous plant Potentilla reptans were allowed to grow in cylinders covered with green foil. These cylinders were raised at three different speeds, to simulate varying growth rates of surrounding vegetation. Plants adjusted the length of new petioles at which cylinders were raised, slowing down their increase in petiole length once they emerged above the top. This lead to similar height of the different genotypes in the two slowest treatments (height convergence). But the genotypes did differ in the ability with which they could keep up with the fastest treatment. Stoloniferous plants strongly adjust their phenotype to the height growth of surrounding vegetation, allowing them to reach the top of the vegetation despite the disadvantage of starting each new leaf from the ground. Genotypic differences indicate that at slow vegetation height growth more genotypes can coexist in the top of the canopy, while at fast speed more segregation in height between the genotypes, and thus in performance, will occur.