Fig. 6

Effect of exogenous Ca²⁺ on JIP-test parameters in leaves of cucumber under normoxic conditions (a), hypoxic treatments (b) and hypoxia + Ca²⁺ treatments (c). Values are means ± SE of three independent experiments. Bars marked with dissimilar letters are significantly different from each other according to Duncan’s multiple range tests (p < 0.05). Fv/Fm, the maximum quantum yield of PSII; Sm, total electron carriers per RC; ABS/RC, the specific energy fluxes (per reaction center, RC) for absorption; ET_o/RC, the specific energy fluxes (per reaction center, RC) for electron transport; DI_o/RC, dissipation at the level of the antenna chlorophylls; TR_o/RC: the specific energy fluxes (per reaction center, RC) for trapping. Performance index (PI) on absorption basis PI_(abs) = (RC/ABS) • [φP_o/(1– φP_o)] [ψ_o /(1– ψ_o)]; Approximated initial slope of the fluorescence transient f(t): M₀ = 4 M_o = 4 • (F_300μs-F₀)/(F_m-F_o)