Foliar Water Uptake of <i>C</i> ₃ Perennial Grasses Under Drought

Abstract Rain, fog, and dew can all provide the conditions necessary to induce direct uptake of water into the foliage of plants. Although grasslands are known to have frequent leaf‐wetting events, the capacity of grasses to conduct foliar water uptake (FWU) is not well understood. Here, we show the results of greenhouse experiments used to quantify FWU during leaf wetting and under a range of drought conditions. Over a 2 week dry down in which irrigation was withheld, a 40% decrease in FWU was observed. In a separate experiment, we quantified FWU capacity using an established submergence method and attempted to relate this to leaf traits such as stomatal density and leaf hydrophobicity. Across the species tested, we found an average FWU of 3.67 0.32 (mg O ) which represented a leaf water content increase of 9.25 0.95% over a 3 hr leaf wetting treatment. We were not able to establish a statistically significant relationship between FWU capacity and the hypothesized leaf traits drivers, but stomatal conductance showed partial control on uptake. Our results indicate that FWU occurs in perennial grasses and may provide some relief during drought. However, we found that the benefits resulting from FWU decrease as drought becomes severe. We conclude with a recommendation for further research into the mechanistic drivers of FWU capacity in perennial grasses.