Effect of moisture stress on composition and yield in leaf resin of Hymenaea courbaril

Previous controlled environment studies of the effect of photoperiod, light intensity and temperature have shown little phenotypic plasticity in leaf resin composition of Hymenaea courbaril which ranges throughout New World lowland tropical ecosystems. The present control chamber study also showed negligible variation in resin composition as a result of moisture status. Although some change in composition occurred under dry treatment conditions, leaf development was retarded and the variation is consistent with the progressive change in composition with leaf development from very young to fully expanded leaves. Yield (mg resin/g leaf tissue), not measured in previous studies, also showed little variation between wet and dry treatments. It is suggested that these indications of low plasticity in both composition and yield in Hymenaea leaf resins may be significant in herbivore interactions.