Chlorophyll Fluorescence May Predict Tolerance to Herbivory

Abstract

Premise of research. Tolerance to herbivory is the capacity of plants to reduce the negative effects of damage on fitness. Increased growth rate and photosynthesis are two important mechanisms behind tolerance to herbivory. The chlorophyll fluorescence parameter Fv/Fm, which reflects photosynthetic performance, has been used to characterize stress effects on plants. Here, we tested the hypothesis that photosynthetic performance, estimated from Fv/Fm, may predict tolerance to herbivory.Methodology. In the greenhouse, we evaluated whether Fv/Fm values measured in recently damaged seedlings of the temperate rainforest tree Aextoxicon punctatum predict relative growth rate (RGR) measured 30 d after damage. RGR was earlier associated with tolerance to herbivory in tree species from this forest. In the field, we determined whether Fv/Fm values in experimentally damaged seedlings of 13 tree species are correlated with their reported levels of tolerance to herbivory.Pivotal results. RGR showed positive associations with Fv/Fm measured 3 h and 30 d after damage but no association with Fv/Fm measured before damage. In undamaged control seedlings, RGR was not related to Fv/Fm at any time evaluated. The across-species comparison in the field showed that Fv/Fm values were positively correlated with reported levels of tolerance to herbivory.Conclusions. The parameter Fv/Fm is an accurate predictor of RGR and tolerance to herbivore damage. We advocate the use of this rapid methodology to estimate plant tolerance to herbivory in natural populations.