Differential Responses of Growth and Two Soluble Phenolics of Tomato to Resource Availability

Abstract

We conducted two experiments to determine how resources influenced the intraspecific and within—plant allocation by tomato plants (Lycopersicon esculentum) to the soluble phenolics rutin and chlorogenic acid. We also measured the effect of resource availability on growth by measuring mass and other physical and cellular attributes of the plant. In the first experiment, we subjected plants to four levels of potassium nitrate fertilizer. In the second experiment, we subjected plants to high and low levels of potassium nitrate fertilizer and light. Both experiments yielded results consistent with the growth—differentiation balance hypothesis. Plants grown with low resources showed low levels of soluble phenolics and low plant mass. Plants grown with intermediate levels of resources showed high phenolic concentrations but inhibited growth. Plants grown with high resources had high growth but no increases in phenolic concentrations. The results were also consistent with the general prediction of the optimal defense hypothesis that there should be a negative relationship between growth and defense. We discuss possible adaptive explanations for the specific patterns observed. There were also consistent within—plant differences in phenolic concentrations. These differences in phenolic concentrations were large enough to have potential consequences for insect herbivores feeding on tomato plants.