Physiological consequences of changes in life form of the Mexican epiphyte Tillandsia deppeana (Bromeliaceae)

Abstract

The heterophyllous epiphyte Tillandsia deppeana exhibits an atmospheric habit as a juvenile and a tank form as an adult. Both juveniles and adults utilize C photosynthesis. This is the first report of an atmospheric form of Tillandsia which does not exhibit CAM. Photosynthetic saturation occurred at approximately 10% of full sunlight in both forms, but the adults exhibited greater rates of photosynthesis at all levels of irradiance. The adults also had a higher and broader photosynthetic temperature optimum than did the juveniles. The adults transpired at greater rates than the juveniles; however, the water use efficiencies of both forms were similar and were high for C plants. In both forms the photosynthetic rate decreased in response to a decrease in humidity. After 8 days without water the juveniles were able to fix CO throughout the day. The adults, however, exhibited a net loss of CO on the second day without water and thereafter. These results indicate that the water-conservative atmospheric juvenile of T. deppeana is well adapted to establishment in the epiphytic habitat.

Adaptive radiation, correlated and contingent evolution, and net species diversification in Bromeliaceae

“…Atmospherics tolerate desiccation better than tank species but have lower rates of photosynthesis per unit leaf mass (Benzing and Burt, 1970;Benzing and Renfrow, 1974;Reyes-Garcia et al, 2008), and almost all have CAM photosynthesis (Crayn et al, 2004). Many tank bromeliads exhibit developmental heterophylly, with juveniles starting as atmospherics (Adams and Martin, 1986;Benzing, 2000;Zotz et al, 2011) and then later forming tanks as body size increases. Krömer et al (2006) found that large, tank-epiphyte bromeliads dominated the rainy, moist eastern slope of the Andes in Bolivia, while atmospheric Tillandsia taxa dominated the drier, more seasonal leeward slope.…”

Drought and extreme temperature tolerance for <em>Tillandsia dasyliriifolia</em>, an epiphytic bromeliad from the northern coastal dune scrubland in Yucatan, Mexico

“…Almost all studies related to bromeliad size have focused on the measurement of the responses of the photosynthetic apparatus, gas exchange, transpiration rates and morphological changes in relation to environmental factors (Adams and Martin, 1986a, b;Zotz, 1997;Zotz and Thomas, 1999). For example, adult tank-forming bromeliads under well-watered conditions show higher rates of CO 2 exchange and transpiration than smaller ones (Adams and Martin, 1986a). Many bromeliads with a rosette growth pattern have the ability to form a tank and store water to avoid drought.…”

Size-related intraspecific variability in physiological traits of vascular epiphytes and its importance for plant physiological ecology

“…In these taxa, early juveniles are atmospheric, while later stages have broad leaves which form a water-impounding tank. Apart from many morphological differences (Adams & Martin 1986a), larger individuals of Tillandsia deppeana show significantly higher rates of CO 2 exchange and transpiration, and differ strongly in stomatal behaviour after the onset of drought (Adams & Martin 1986b). Conceptually, however, these studies did not represent much progress, because in both cases the authors treated the differences between "juvenile" and "adult" as step-like changes in plant form.…”