Impact of Drought, Heat, and Their Combination on Chlorophyll Fluorescence and Yield of Wild Barley (Hordeum spontaneum)

Figure 1

Effect of drought, heat, or their combination on Performance Index (, a), the maximum quantum yield of PSII (, b), the relative fraction of active reaction centers (RCs/ABS, c), and the relative amplitude of the IP-phase of the OJIP induction curve (, d). Values are presented relative to the unstressed control group; DA = drought acclimated, HS = heat stress, CS = combined stresses, S = stress, and R = recovery; mean + SD, . Asterisks inside the columns represent significance in comparison to control values (=100%), asterisks above the connecting brackets indicate significance between stress and recovery within one treatment. Significant changes were marked with one (), two (), or three () asterisks.

(a)

(b)

(c)

(d)