Fig 4. The difference kinetics and the relative variable fluorescences calculated from OJIP analysis of two maize genotypes (2023 and CE704).

The difference kinetics ΔW_OJ (A) reveals the K-band; ΔW_OK (B) reveals the L-band. Only the part between the I and P points of the OJIP curve is shown for the relative variable fluorescence W_OI (C). The normalization of OJIP curve between the I and P points with the maximum amplitude fixed as 1 is shown as the relative variable fluorescence W_IP (D). Plants were subjected either to normal watering (control) or to 14 days of withholding water (stress). ΔW_OJ and ΔW_OK were calculated from the comparisons of the stressed and control plants; the latter are represented by the zero point of the respective y axes in graphs A and B. Mean values (n = 8) are shown. r.u. … relative units.