Phenotypic plasticity to light competition and herbivory in Chenopodium album

Little is known about how the expression of plasticity affects subsequent plasticity in response to new environments. I addressed this question in two ways: first, by exposing plants to light competition and then subsequently challenging them with insect herbivory, and second, by exposing plants to herbivory and then subsequently challenging them with light competition. Since both light competition and herbivory affect resources available to plants, I also controlled for the effects of resource reduction when these factors are imposed. I found that an initial plant response to light competition attenuated the subsequent expression of induced resistance on whole plants but not on excised leaves. I also found that an initial response to herbivory did not affect subsequent response to light competition as measured by plant height. Therefore, I found that plants are able to express phenotypic plasticity following previous expression of plasticity to a different environmental factor.