Red Leaf Flushing in Tropical Plants

Abstract

Red-leaf flushing is a conspicuous phenomenon in tropical woody plants due to the production of anthocyanins in developing leaves and shoots. It has been suggested that the red colouration can provide protection against photodamage or by making the leaves cryptic to herbivores. This project investigated red-flushing by comparing the herbivory rate of 12 red-flushing species with 8 normal-greening species. Red young leaves were grazed more rapidly than both normal greening young leaves and mature leaves of red-flushing species. Red young leaves showed no increased resistance, or were even more susceptible, to herbivory than controls. Measurement of the rate of photosynthesis revealed that young red leaves showed smaller inhibition at high light intensity when compared to green young leaves. For dark recovery following photoinhibition, anthocyanin-pigmented young leaves were able to recover 69% of fluorescence yield while nonanthocyanin-pigmented young leaves only recovered 58%. Red young leaves were more resistant to photo damage supporting the photoprotection hypothesis.