Foliar water uptake of woody plants of arid ecosystems

BLANDI A; FIEDEROWICKS KOWALL R; ARIAS N; ASKENAZZI J; IOGNA PA; SCHOLZ FG; BUCCI SJ

Buzios

Congreso; Brazilian Congress of Plant Physiology; 2011

Precipitation in many arid and semiarid environments most frequently occurs as medium to small events, with few if any large events occurring during drier periods without a increasing in soil wetness. Thus the wetting of leaves and plant crown with dew, short rain or precipitation, may provide a significant water supply and could have a positive effect on water balance of the leaves. The objective of this study was to investigate direct water uptake by leaves and its relationship with leaf morphophysiological traits in seven species growing in Patagonian cold desert, where leaf-wetting events by dew or small rain frequently occur throughout drought-prone season. We determined the direct foliar water uptake, increase in leaf water content (LWC), and specific leaf area in 5 leaves of each species. Foliar water uptake varied from 0.011 to 0.003 g cm-2 which provided direct hydration to leaves, increasing leaf water content from 5 to 31% depending of the species. The species with highest increase in LWC were Grindelia chiloensis and Retanilla patagonica, whereas Colliguaja integerrima presented the lower change in LWC. There was a relationship between increase in LWC and specific leaf area. Species with higher increase in LWC exhibited the higher specific leaf area.   These results suggest that foliar water uptake can be considered as an additional drought-avoiding mechanism of Patagonian desert species complementary to observed osmoregulation and elastic adjustment. At night, leaf water uptake could avoid the nocturnal disequilibrium in soil to leaf water potential, improving the CO2 exchange by maintaining open stomata in the early morning.