Authors: J D Beltrán E Lasso S Madriñán A Virgo K Winter
Publish Date: 2012/12/27
Volume: 51, Issue: 1, Pages: 55-62
Abstract
In the epiphytic tillandsioids Guzmania monostachia Werauhia sanguinolenta and Guzmania lingulata Bromeliaceae juvenile plants exhibit an atmospheric habit whereas in adult plants the leaf bases overlap and form waterholding tanks CO2 gasexchange measurements of the whole intact plants and δ13C values of mature leaves demonstrated that C3 photosynthesis was the principal pathway of CO2 assimilation in juveniles and adults of all three species Nonetheless irrespective of plant size all three species were able to display features of facultative CAM when exposed to drought stress The capacity for CAM was the greatest in G monostachia allowing droughtstressed juvenile and adult plants to exhibit net CO2 uptake at night CAM expression was markedly lower in W sanguinolenta and minimal in G lingulata In both species lowlevel CAM merely sufficed to reduce nocturnal respiratory net loss of CO2 δ13C values were generally less negative in juveniles than in adult plants probably indicating increased diffusional limitation of CO2 uptake in juvenilesAcknowledgements JDB was recipient of a shortterm fellowship from the Smithsonian Tropical Research Institute and received travel support from the Facultad de Ciencias Universidad de los Andes Dayana Agudo performed the δ13C analyses Jorge Ceballos helped with microscopy and Oris Acevedo provided logistical support on Barro Colorado Nature Monument
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