Making dew in the Atacama Desert: a paradigmatic case of plant water uptake water from an unsaturated atmosphere fails a test.

Background And Aims: Nolana mollis is a dominant plant species in the hyperarid Atacama Desert. A previous hypothesis states that N. mollis owes its success to the condensation of atmospheric water from undersaturated air onto its leaf surfaces by exuded salts, and absorption of this water by its leaves, or by shallow roots following drip onto the soil surface; living roots of N.

Water Loss From Bagged Leaves During Storage: Why and When?

In ecophysiology leaves are frequently stored for hours after sampling before measuring their leaf water potential (Ψ). Here, we address a previously unidentified source of error, that metabolic heat generation can cause continuous water loss from leaves stored in impermeable bags, leading to a Ψ drop over time. We tested Ψ drop rates under various conditions: two bag materials, two species, initial Ψ above or below the turgor loss point (Ψ), and storage at 25°C versus 4°C.

Shorting the metaphorical circuit: vascular partitioning and stomatal patchiness can create apparent unsaturation and CO gradient inversion in the Ohmic analogy for leaf gas exchange.

Analyses of leaf gas exchange rely on an Ohmic analogy that arrays single stomatal, internal air space, and mesophyll conductances in series. Such models underlie inferences of mesophyll conductance and the relative humidity of leaf airspaces, reported to fall as low as 80%. An unresolved question is whether such series models are biased with respect to real leaves, whose internal air spaces are chambered at various scales by vasculature.

Dynamic soil hydraulic resistance regulates stomata.

The onset of stomatal closure reduces transpiration during drought. In seed plants, drought causes declines in plant water status which increases leaf endogenous abscisic acid (ABA) levels required for stomatal closure. There are multiple possible points of increased belowground resistance in the soil-plant atmospheric continuum that could decrease leaf water potential enough to trigger ABA production and the subsequent decreases in transpiration.

New approaches to dissect leaf hydraulics reveal large gradients in living tissues of tomato leaves.

The water status of the living tissue in leaves is critical in determining plant function and global exchange of water and CO. Despite significant advances in the past two decades, persistent questions remain about the tissue-specific origins of leaf hydraulic properties and their dependence on water status. We use a fluorescent nanoparticle reporter that provides water potential in the mesophyll apoplast adjacent to the epidermis of intact leaves to complement existing methods based on the Scholander Pressure Chamber (SPC).