Patterns of leaf surface wetness for montane and subalpine plants

Abstract

The frequency and duration of water on leaf surfaces have important consequences for plant growth and photosynthetic gas exchange. The objective of the present study was to compare the frequency and duration of leaf wetness under natural field conditions among species and to identify variation in structural features of leaves that may reduce surface wetness. During June-Septemher 1992 in the central Rocky Mountains (USA), natural leaf wetting due to rain and dewfall was observed on 79 of 89 nights in open meadow habitats compared to only 29 of 89 nights in the understorey. Dew formation occurred at relative humidities that were often well below 100% because of radiational heat exchange with cold night skies and low wind speeds (< 0-5 m s~*). A survey of 50 subalpine/montane species showed that structural characteristics associated with the occurrence and duration of leaf surface wetness differed among species and habitats. Both adaxial and abaxial surfaces accumulated moisture during rain and dewfall events. Leaf surfaces of open-meadow species were less wettable {P = 0-008), and had lower droplet retention (F = 0-015) and more stomata {P = 0-017) than adjacent understorey species. Also, leaf trichomes reduced the area of leaf surface covered by moisture. Ecophysiological importance is suggested by the high frequency of leaf wetting events in open microsites, influences on growth and gas exchange, and correspondence between leaf surface wettability and habitat.

Wettability, Polarity, and Water Absorption of Holm Oak Leaves: Effect of Leaf Side and Age

“…The adaxial and abaxial holm oak leaf side performed differently in terms of wettability (Table I), as previously found for other plant species (Brewer and Smith, 1997;Fernández et al, 2014). We showed that the hydrophobic character of the abaxial leaf side is clearly associated with the roughness provided by the high density, chemical composition, and structure of trichomes.…”

“…We showed that the hydrophobic character of the abaxial leaf side is clearly associated with the roughness provided by the high density, chemical composition, and structure of trichomes. According to the classification suggested by Brewer et al (1991) and Brewer and Smith (1997), the abaxial holm oak leaf trichomes may belong to the lifting strategy group, while further trials will require characterizing the performance of liquid water with the adaxial oak leaf side at a macroscopic level.…”

“…Such surface features together with their chemical composition (Khayet and Fernández, 2012) may lead to a high degree of roughness and hydrophobicity (Koch and Barthlott, 2009;Konrad et al, 2012). The interactions of plant surfaces with water have been addressed in some investigations (Brewer et al, 1991;Brewer and Smith, 1997;Pandey and Nagar, 2003;Hanba et al, 2004;Dietz et al, 2007;Holder, 2007aHolder, , 2007bFernández et al, 2011Fernández et al, , 2014Roth-Nebelsick et al, 2012;Wen et al, 2012;Urrego-Pereira et al, 2013) and are a topic of growing interest for plant ecophysiology (Helliker and Griffiths, 2007;Aryal and Neuner, 2010;Limm and Dawson, 2010;Kim and Lee, 2011;Berry and Smith, 2012;Berry et al, 2013;Rosado and Holder, 2013;Helliker, 2014). On the other hand, the mechanisms of foliar uptake of water and solutes by plant surfaces are still not fully understood (Fernández and Eichert, 2009;Burkhardt and Hunsche, 2013), but they may play an important ecophysiological role (Limm et al, 2009;Johnstone and Dawson, 2010;Adamec, 2013;Berry et al, 2014).…”

“…The importance of trichomes and pubescent layers on water drop-plant surface interactions and on the subsequent potential water uptake into the organs has been analyzed in some investigations (Fahn, 1986;Brewer et al, 1991;Grammatikopoulos and Manetas, 1994;Brewer and Smith, 1997;Pierce et al, 2001;Kenzo et al, 2008;Fernández et al, 2011Fernández et al, , 2014Burrows et al, 2013). Trichomes are unicellular or multicellular and glandular or nonglandular appendages, which originate from epidermal cells only and develop outwards on the surface of plant organs (Werker, 2000).…”

Diurnal variations of photosynthesis and dew absorption by leaves in two evergreen shrubs growing in Mediterranean field conditions

“…Our results with L. stoechas are in accordance with Garrat & Segal (1988), who reported that dew provides significant amounts of water especially relevant in water-stressed plants. Although water precipitated on the leaf surface causes an immediate depletion of leaf gas exchange (Smith & McClean, 1989 ;Ishibashi & Terashima, 1995 ;Brewer & Smith, 1997), once dew water is absorbed from the leaf surface, the photosynthetic performance of water-stressed plants can be improved through increased plant water status (Grammatikopoulos & Manetas, 1994 ;Munne! -Bosch & Alegre, 1999).…”