Abstract Detail


Ewers, Frank [1], Lopez-Portillo, Jorge [2], Angeles, Pedro G. [3], Mendez-Alonzo, Rodrigo [4].

Leaf indument and water in mangrove trees – is it a love-hate relationship?

A leaf surface of dense trichomes, the indumentum, may play a role deterring herbivory, water retention, foliar water absorption, or in reflecting light and thus reducing heat load. We used a tensiometer to quantify the interaction of leaf surfaces with water comparing glabrous and hairy ecotypes of the black mangrove plant Avicennia germinans.  The glabrous surfaces, whether ad- or abaxial, were somewhat hydrophyllic and rather stable over time, with contact angles ranging from about 40 to 85 degrees. In contrast, the hairy abaxial surfaces were quite unstable, ranging from hydrophobic when dry (110 degrees) to extremely hydrophilic, with contact angles as low as zero degrees when the surfaces were sufficiently wet. For a pre-moistened indument, over a twenty minute period, the contact angle dropped from 40 degrees down to zero degrees, during which time glabrous surfaces dropped from 65 degrees down to only 55 degrees.  When the leaves were oven dried at 40 C, there was little effect on the glabrous surfaces, but the indument surfaces became hydrophobic, with a contact angle of about 110 degrees. The contact angle results were matched with physiological measurements, which indicated that leaves with indument had rapid foliar water uptake for up to thirty minutes after exposure to moisture.  However, the same indument leaves, but with with dried leaf surfaces, had reduced water loss over a 16 hour period. The glabrous leaver were “cheaper”; they may allow faster growth rates. Glabrous versus hairy leaves had specific leaf mass (in g m-2) of 116 (SE 6) versus 142 (SE 3) in seedlings and 107 (SE 6) versus 152 (SE 14.1) in adults. Although implying higher construction costs, hairy leaf advantages lie on being effective at reducing water loss during dry conditions, promoting water absorption during wet conditions, reducing herbivory, and perhaps improving leaf life span.

1 - California State Polytechnic University, Pomona, Department Of Biology, 3801 West Temple Avenue, Pomona, CA, 91768, United States
2 - Carretera Antigua A Coatepec 351, El Haya, Xalapa, Veracruz, 91070, Mexico
3 - Instituto De Ecologia, A.C., Ecologia Funcional, Carretera Antigua A Coatepec No. 351., El Haya, Xalapa, Veracruz, VER, 91070, Mexico
4 - CICESE, Departamento de Biología de la Conservación, Ensenada, Baja California, Mexico

water stress
black mangrove
Avicennia germinans

Presentation Type: Oral Paper
Session: ECOPH3, Ecophysiology III
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 3:00 PM
Number: ECOPH3001
Abstract ID:424
Candidate for Awards:None

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