Submersion of plant shoots and leaves in water is common practice in studies of rehydration kinetics and foliar uptake, as well as a widely accepted way to recover water-stressed samples before making anatomical preparations and physiological measurements. While frequently wet in the field, most plant leaves are never subject to submersion or near-zero water potentials. In questioning our own use of foliar submersion, we compared the rehydration kinetics of leaves that were submerged, hydrated with cut-ends in water, and hydrated in fog. We additionally combined micro CT scanning and green-sectioning of shoots hydrated by these three methods to visualize potential structural impacts of submersion.
Results/Conclusions
Submerged shoots gained weight and increased their water potentials substantially faster than did shoots hydrated by other methods. Both micro CT scanning and green sectioning revealed clear damage to leaf mesophyll after being under only ~ 2 cm water. We suspect that the slight positive pressure induced by submersion forces water into the leaf in an unnatural way. We caution the use of foliar submersion as a hydration technique in physiological and anatomical studies.