Relationships among growth, development and plastic response to environment quality in a perennial plant

Phenotypic traits differ between plants in different environments and within individuals as they grow and develop. Comparing plants in different environments at a common age can obscure the developmental basis for differences in phenotype means in different environments. Here, we compared trait means and patterns of trait ontogeny for perennial (Viola septemloba) plants growing in environments that differed in quality either naturally or due to experimental manipulation. Consistent with predictions for adaptive stress resistance, plants grown in lower-quality environments allocated proportionately more biomass to roots and rhizomes, and produced smaller, thicker and longer-lived leaves. The developmental trajectory of almost all traits differed between environments, and these differences contributed to observed differences in trait means. Plants were able to alter their initial developmental trajectory in response to an increase in resources after 8 wk of growth. This result contrasts with previous findings, and may reflect a difference in the way that annual and perennial species respond to stress. Our results demonstrate the complexity of interactions between the environment and the development of the phenotype that underlie putatively adaptive plastic responses to environment quality.