Abstract Detail



Physiology

Ewers, Frank [1], Angeles, Guillermo [2], Mendez-Alonzo, Rodrigo [3], Quintanar, Alejandra [4], Lopez-Portillo, Jorge [5].

The effect of dense leaf hairs on the water relations of two mangrove tree species.

Hairy and glabrous varieties of two mangrove species were examined to test the effect of leaf trichomes on the absorption and release of water by the leaf surfaces. In Avicennia germinans most plants have a dense indumentum of trichomes on the abaxial surface.  A glabrous variety lacked those trichomes on many of their leaves. In Conocarpus erectus the green variety (var. erectus) had few trichomes, but var. sericeus had a dense indumentum of trichomes on both surfaces resulting in a silver appearance. Water absorption and evaporation experiments indicated that in both species, under dry conditions, the dense indumentum varieties had slower water loss than glabrous varieties. However, when immersed in water the hairy varieties showed very rapid uptake of water. This was followed by an initially high rate of water loss when dehydrated once again. Perhaps the hairy varieties had improved water relations as a result of apoplastic uptake of water by non-living trichome cells, which may improve the boundary layer conditions surrounding the stomates.  Ironically, tensiometer measurements indicated that the hairy leaf surfaces were initially extremely hydrophobic as water drops beaded up on the surface. However, over a 15 minute period drops of water were absorbed by the hairy but not the glabrous leaves. The dense indumentum may also deter herbivory, as reported in the literature for Conocarpus. In contrast one advantage to the glabrous condition appears to be reduced construction costs of leaves; for hairy versus glabrous leaves the leaf mass per area was 22.4 % greater in hairy leaves of Avicennia and 18.4% greater in hairy leaves of Conocarpus.


1 - California State Polytechnic University, Pomona, Department Of Biology, 3801 West Temple Avenue, Pomona, CA, 91768, United States
2 - Instituto De Ecologia, A.C., Ecologia Funcional, Carretera Antigua A Coatepec No. 351., El Haya, Xalapa, Veracruz, VER, 91070, Mexico
3 - CICESE, Ensenada, MX
4 - Universidad Autonoma Metropolitana-Iztapalapa, Departmento de Biologia, Mexico City
5 - Instituto De Ecologa, A.C., Red De Ecologa Funcional, Carretera Antigua A Coatepec 351, El Haya, Xalapa, Veracruz, VER, 91070, Mexico

Keywords:
none specified

Presentation Type: Oral Paper
Number: 0009
Abstract ID:533
Candidate for Awards:None


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