The ratio of variable fluorescence to maximum fluorescence (Fv/Fm), representing the maximum photochemical efficiency of photosystem II (PSII), was determined using a portable chlorophyll fluorometer (OptiSci OS-30p Chlorophyll Fluorometer, Opti-Sciences Inc, USA).
They showed that metal limitation impairs the photosynthetic efficiency of photosystem II34,42,43 and enhances the oxidative load, by decreasing antioxidant enzymes' activity and ROS consumption42.
UV-B induced a transient decrease in net photosynthesis (Anet), actual and maximum potential efficiency of photosystem II, particularly on well watered plants.
Photosystem II damage was evident in the less tolerant genotypes (e.g. at 30 mM NaCl, actual quantum efficiency of photosystem II values were 63 96% of controls).
In plants subjected to drought stress, the overexpression of DREB genes derived from Arabidopsis led to greater increases in Fv/Fm (maximum quantum efficiency of photosystem II), relative water content, and proline content.
Operational Efficiency of Photosystem II.
Photochemical efficiency of photosystem II.
expressed sequence tag. the maximum quantum efficiency of photosystem II.
P values of effected cells via efficiency of photosystem II.
Figure 5 Electrolyte leakage and efficiency of photosystem II from banana fruit peels.
High P uptake is responsible for maintaining optimum leaf relative water contents, efficiency of photosystem II and net photosynthetic rate.
