Ecophysiology of five Mediterranean perennial grasses: II) Effects of shade on gas exchange

ABSTRACT

Five perennial grasses characteristic of different Mediterranean environments (Ampelodesmos mauritanicus (Poiret) Dur. et Sch., Brachypodium ramosum (L.) R. et S., Festuca drymeia M. et K., Brachypodium sylvaticum (Hudson) Beauv., Festuca heterophylla Lam.) were pot cultivated at two different levels of light intensity. Gas exchanges were studied by a Li-Cor 6400 Portable Photosynthesis System. Light response curves revealed a greater photosynthetic potential for the species of open habitats, though maximum carbon uptake was much lower among shaded replicates. On the contrary, the species from shaded habitats exhibited lower net photosynthesis at saturation but small differences between plants grown in light or shade. The five species showed relevant differences with respect to transpiration and water use efficiency. Results provide useful information on the ecophysiology of these species in relation to their different field distribution.

KEY WORDS:

• photosynthesis
• transpiration
• light curve
• shade tolerance
• plasticity