2.4 Chlorophyll (Chl) content measurements
Chl content was determined according to Porra et al. (1989). Leaf
segments (0.1 g) were first washed with distilled water and then kept in
1 ml acetone (80%) at 4°C for one to two weeks. Then samples were
centrifuged at 13,000 g for 5 min and subsequently their absorbance was
monitored at 663 and 645 nm using a UV visible spectrophotometer (50 Bio
Varian, Varian Inc., Walnut Creek, CA). Total Chl content was calculated
according to the following equation: total Chl
(mg·L−1) = (8.02 × OD663) + (20.21 ×
OD645), where OD stands for optical density. The results
of the Chl content were expressed as mg per gram fresh weight (mg
g−1 fresh weight (FW)) and calculated based on the
extinction coefficients and the equations given by Porra et al. (1989).