Starch, soluble sugars and chlorophyll measurements
Soluble sugars and starch were determined by the anthrone method (Yemm
and Willis 1954). Pigments were extracted and determined according to
the method described by Markwell et al. (1986). The contents of
chlorophylls a and b were calculated using the formulas
described previously (Porra et al ., 1989) and expressed as μg
pigment g–1 fresh weight
(FW).