Allometry of Corispermum macrocarpum in response to soil nutrient, water, and population density

The allometric effects of Corispermum macrocarpum Bunge in response to soil nutrient content, water content, and population density were compared in a greenhouse experiment. The results showed that biomass allocation was size-dependent. The plasticity of roots, leaf allocation, and reproductive effort was true plasticity (i.e., changing biomass allocation in response to environmental conditions regardless of plant size), and no plasticity was detected in stem allocation in response to soil nutrient variation. At a low soil nutrient content, C. macrocarpum allocated more resources to reproductive organs than to roots and leaves at equivalent plant size, but the value of root allocation was consistent because of the trade-off between the effects of plant size and soil nutrient content. In the response to soil water variation, the plasticity of root allocation and reproductive effort was true plasticity, the plasticity of stem allocation was apparent plasticity (i.e., changing biomass allocation in response to plant size regardless of environmental conditions), which was caused by plant size, but there was no plasticity in leaf allocation. Except for the true plasticity of root allocation, there was no plasticity in stems, leaves, and reproductive organs in response to population density.