3.3. Diurnal and WS-related changes in ABA and SA accumulation
in leaves
Endogenous ABA concentrations kept constant around 650 ng/g
DW throughout the study in IR plants, while they increased to ca.
1100 ng/g DW after 4 days of water deficit in WS plants (Fig. 4).
ABA levels did not increase further under stress and kept at similar
high levels after 10 and 15 days of water deficit, with values 75%
and 64% higher in WS plants compared to IR plants, respectively.
SA levels were not significantly different throughout the study
between IR and WS plants (Fig. 4). While no clear patterns of
diurnal variations in ABA levels were observed either in IR or WS
plants, endogenous concentrations of SA were severely affected by
the time of day in both plant groups (Fig. 5). Endogenous SA
concentrations were at their highest during the night and at early
morning, while they attained their lowest values during the
afternoon in IR plants, or midday and afternoon in WS plants.
Diurnal variations in SA concentrations were identical in IR andWS
plants, except that minimum levels during the day were attained
earlier in WS plants compared to IR plants (Fig. 5).