Changes in leaf water use after removal of leaf lower surface hairs onMallotus macrostachyus(Euphorbiaceae) in a tropical secondary forest in Malaysia

Abstract

Leaf hairs may assist in maintaining high leaf water use efficiency in tropical secondary forest tree species. We compared leaf temperature, transpiration, photosynthesis and water use efficiency between hairy and depilated leaves in Mallotus macrostachyus (Euphorbiaceae), to determine the role of leaf hair in leaf water use efficiency (WUE) in tropical degraded secondary forest in Malaysia. Measurements were made on five mature individuals growing in sun-exposed conditions and five in shaded conditions. The hair dry weight per unit leaf area was significantly greater in sun leaves than in shade leaves. The transpiration rate (Tr max ) of depilated leaves in sunexposed conditions was slightly higher than in hairy leaves in both morning and afternoon measurements. In contrast, Tr max in the shade leaves was almost identical in hairy and depilated leaves. Leaf stomatal conductance (g s ) in the morning showed almost the same value among leaf types and light conditions. In the afternoon, g s slightly decreased from the morning values in both sun and shade conditions. In the morning, the leaf water use efficiency (A max /Tr max ) in both conditions did not differ significantly between hairy and depilated leaves. However, in the afternoon, WUE in the depilated leaves was significantly lower than in hairy leaves in sun-exposed conditions. These observations suggest that leaf hairs in M. macrostachyus contribute to the high leaf water use efficiency in drought conditions, such as high vapor pressure deficit experienced at midday in degraded tropical secondary forests.

Variations in Leaf Photosynthetic and Morphological Traits with Tree Height in Various Tree Species in a Cambodian Tropical Dry Evergreen Forest

“…The CO 2 concentration and air humidity in the leaf chamber were maintained at 360 ppm and approximately 60%, respectively. The photosynthetic rate at light saturation (A max-area , µmol m -2 s ) at light saturation were also recorded and water use efficiency (WUE), which is the ratio of A max-area and gs max-area , was calculated 33,34 . The sampled leaves were then divided into two parts without large veins: one for measuring leaf hardness, leaf mass per area (LMA, g m -2 ), nitrogen content and stable carbon isotope composition (δ 13 C, ‰); the other for observing leaf morphology such as stomatal density and the mesophyll structure 30 .…”

“…7). Increasing leaf-massbased WUE with tree height was key to advantageous photosynthetic production under the drought condition of the canopy 34,42 . In addition, linear increase in leaf δ 13 C values with tree height (Fig.…”

New Insights into the Properties of Pubescent Surfaces: Peach Fruit as a Model

“…Some studies performed with leaves of Olea europaea, Tillandsia species, and Mallotus macrostachyus failed to find a clear relationship between trichome layers and transpiration Benz and Martin, 2006;Kenzo et al, 2008).…”

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

“…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).…”