A preliminary investigation into the relationship between petiole and water-related traits in tropical flowering trees

Abstract

Water deficit impacts photosynthetic productivity and whole plant energy budgets, and generally leads to stress and decreased growth. The petiole plays a key role in mitigating against water stress, as the petiole is the terminal region of water transport before the leaf. This study investigated the relationship between petiole traits, leaf traits and plant lifespan. We studied petiole and petiole xylem dimensions in 10 species of tropical rainforest tree species, and compared this to the relative growth rates (RGR) and leaf areas (LA) of those same species. First, we found that petiole volume accurately predicts potential petiole conduit hydraulic conductance (R²= 0.992; n= 7). Second, we found petiole volume and LA to be correlated across families (R²=0.859; n=48). Lastly, we found weak intra-family correlation between petiole volume and RGR, but this did not hold across families. Improved knowledge about the role of the petiole in water relations will inform future study into physiological responses to water stress. This is especially pertinent given the concerns about increasing drought conditions in the tropics under predicted climate change scenarios.