Energy transfer efficiencies (φPo, φEo and ψ_o), overall performance index of photosystem II (PSII) (PI_ABS) and specific energy fluxes in PSII (ABS/RC, TR_o/RC and ET_o/RC) for different sampling dates.

<p>Values shown are relative to results obtained from the medium winter-hardy wheat cultivar Muszelka (red line). Data for laboratory cold-acclimated plants are the means of two independent experiments. Values marked with the same letter denote the lack of statistical significance between cultivars of triticale (italicized) and wheat (<i>P</i> = 0.05, Tukey’s HSD test). Statistical significance of differences between species is indicated by asterisks outside the graphs (<i>P</i> = 0.05, <i>t</i>-test).