Abstract
Foliar water uptake (FWU) may be a significant way for trees to obtain
water; however, studies are lacking on FWU. To determine whether FWU
occurs in Platycladus orientalis growing in seasonally arid areas, the
process of FWU under soil water content (SWC) of 3.9–6.5%, 6.5–9.1%,
9.1–15.6%, 15.6–20.8%, and 20.8–26.0% and different precipitation
gradients (1/mm, 5 mm/h, 10 mm/h, and 15 mm/h) was studied using
precipitation with labeled isotopes in simulated rainfall experiments
with indoor potted plants. The results showed that FWU occurred in each
treatment if the SWC ≤ 21.9% no matter the amount of precipitation. The
absorption rate of rainfall by leaves increased with the increase of
rainfall intensity, but decreased with the increase of SWC. The greatest
rates of FWU were 2.77% and 9.52% of rainfall intensity of 1 mm/h and
15 mm/h, respectively, in the 3.9–6.5% treatment. The precipitation
absorbed by the leaves of P. orientalis can be transported to xylem or
root system along the water potential gradient of
leaves–branches–roots. The precipitation with reverse migration in
branches and roots increased with the increase of the water potential
gradient of leaves–branches–roots. This study provided insight into
water use patterns and water migration within trees.