Effects of the Microstructural Characteristics of Leaves on the Dew Evaporation Duration and Absorption Capacity

Dew is an important supplementary water source, and the dew evaporation duration and the amount absorbed by leaves differ significantly among species. To explore the dew evaporation duration and proportion of dew absorbed by leaves (Fu) of different plant leaves, seven potted plant species were selected to carry out laboratory experiments. The results showed that the dew evaporation duration of the seven plants ranged from 35'05" ± 1'23" to 69'50" ± 1'50". The order of dew evaporation duration was hydrophobic leaves > hydrophilic leaves with trichomes > hydrophilic leaves without trichomes. All the plants selected in the experiment could directly absorb water through the leaf surface. As a xerophytic plant, Crassula arborescens had the highest Fu (50.18 ± 8.51%), which was significantly higher than that of other plants. The Fu values of Chlorophytum comosum, Syringa oblata, Begonia obsolescens, Ardisia mamillata, Juniperus formosana and Oxalis corniculata were 19.29 ± 1.75%, 13.72 ± 1.98%, 10.07 ± 2.96%, 7.14 ± 1.09%, 5.17 ± 1.66%, and 1.08 ± 0.44%, respectively. The Fu was positively correlated with water content (Wa) and leaf mass per unit of leaf area (LMA) (P < 0.01). The water absorption capacity of leaves increased with increasing Wa and LMA. The leaf surface was covered with high-density, long and hydrophobic trichomes, which prevented dew droplets from contacting the leaf surface directly, and the conditions were not conducive to absorbing dew. Leaves with three-dimensional wax are generally weak in absorbing dew, while leaves with two-dimensional wax are usually strong in absorbing dew. The hydrophilic leaf surface of xerophytic plants allows them to absorb more dew, which is one of the survival strategies of plants in arid regions.