INVESTIGADORES
FERNANDEZ Maria elena
artículos
Título:
. Growth of the grass Festuca pallescens in silvopastoral systems in a semi-arid environment, Part 2: Parameterization of models of stomatal conductance and leaf photosynthesis
Autor/es:
MARIA ELENA FERNANDEZ; GYENGE, J.; SCHLICHTER, T.
Revista:
Agroforestry Systems
Referencias:
Año: 2006 vol. 66 p. 271 - 280
ISSN:
0167-4366
Resumen:
A combined model of stomatal conductance and
photosynthesis was developed for Festuca
pallescens (St. Ives) Parodi, a
forage species in Patagonia. Curves showing the relationship between
photosynthesis and photosynthetic photon flux density (PPFD) were constructed
for plants grown under differing levels of water availability, relative
humidity (RH) and air temperature (T). Stomatal conductance (gs) was related to these
variables and pre-dawn leaf water potential (wpd) using an empirical multiplicative submodel.
Parameters of the photosynthesis-PPFD curves were related to the average gs values for each curve to
introduce stomatal limitation on photosynthesis. Considering the simplicity of
the models, estimated stomatal conductance and photosynthesis agree
satisfactorily with independent measured
values in the field and in the glasshouse,
particularly in the range of low and medium values of both variables (R2 = 0.84 and 0.87 for gs and photosynthesis
models, respectively). PhotosynthesisPPFD
curves were also determined under field conditions for plants growing under
shade and in the open, in a silvopastoral trial in northwestern Patagonia. No
significant differences in the photosynthetic light response curves were found
between these locations, but slight increases in maximum assimilation rate and quantum
yield (light use efficiency) were found for leaves grown under shade. This
study of environmental influences on photosynthesis in F. pallescens may help to predict its capacity to grow under trees in
silvopastoral systems. In addition, this simple model may be easily
parameterised for other species to predict photosynthetic responses under
different environmental conditions.