Physiological and biometrical measurements started almost immediately (1 DAT for
fluorescence measurements and 11 DAT for photosynthesis). Measurements of Fv/F m
and quantum yield of electron flow to PSII of attached leaves were made using a
PAM-2000 portable fluorometer (Walz, Germany). Further information regarding the
measurements is given in a previous paper (Alvino and Sorrentino, 1996). Within each
group of shaded and unshaded plants, leaves were chosen for their natural orientation
and inclination on the plant and arranged in several groups: apical (A), medial (M) and
basal (B).