Phenotypic Responses of a Stoloniferous Clonal Plant Buchloe dactyloides to Scale-Dependent Nutrient Heterogeneity.

Abstract

Clonal plants could modify phenotypic responses to nutrients heterogeneously distributed both in space and time by physiological integration. It will take times to do phenotypic responses to modifications which are various in different growth periods. An optimal phenotype is reached when there is a match between nutrient conditions and foraging ability. A single plantlet of Buchloe dactyloides with two stolons was transplanted into heterogeneous nutrient conditions. One stolon grew in homogeneous nutrient patch, while the other cultured in different scales of heterogeneous nutrient patches. As compared to the other nutrient treatment, heterogeneous nutrient treatments with small scale of 25×25 cm resulted in a higher biomass, and larger number of ramets, clumps and stolons in B. dactyloides at both genet and clonal fragment levels. Significant differences of number of ramets, clumps and stolons were detected at the rapid growth stage, but not in the early stage of the experiment. Foraging ability was more efficient in heterogeneous than in homogeneous nutrient conditions as assessed by higher root mass and root to shoot ratio. Different nutrient treatments did not prompt significant differences in internode and root length. Physiological integration significantly increased biomass, but did not influence other growth or morphological characters. These results suggest that physiological integration modifies phenotypic plasticity of B. dactyloides for efficient foraging of nutrients in heterogeneous nutrient conditions. These effects are more pronounced at genet and clonal fragment levels when the patch scale is 25×25 cm. Time is a key factor when phenotypic plasticity of B. dactyloides in heterogeneous nutrient conditions is examined.