Photosynthetic response to different light intensities, water status and leaf age of two Berberis species (Berberidaceae) of Patagonian steppe, Argentina.

P PERI; M ARENA; G MARTÍNEZ PASTUR; MV LENCINAS

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Lugar: Dordrecht; Año: 2011 vol. 75 p. 1218 - 1222

0140-1963

ABSTRACT: Net photosynthetic rate (A) and stomatal conductance (gs) in leaves of Berberis buxifolia and B. heterophylla seedlings were measured at different light intensity (20 to 2200 µmol m-2 s-1 photosynthetic photon flux density, PPFD) under water stress and for different leaf age. Berberis buxifolia had higher A values than B. heterophylla for all light intensities measured with a maximum value of 27.6 µmol CO2 m-2 s-1 and saturated at 1500 µmol m-2 s-1 PPFD. Values of gs for both Berberis species also declined with light intensity. A negative relationship between A and water stress expressed as pre-dawn leaf water potential (ψlp) were observed, where the reduction in gs was the main factor that reduced A in both species. Also, A and gs of Berberis seedlings quickly increased during the first days after leaf unfolding, reached a maximum value when the leaf was completely expanded (at 30 and 45 days for B. buxifolia and B. heterophylla, respectively), and then declined. These photosynthetic results of Berberis leaves to different light intensities, water stress and leaf age could be used to estimate the responses of seedling establishment and growth to environmental conditions in the native steppe ecosystem or in commercial orchards under irrigation and pruning practices, and also to assist restoration plans.