Chlorophyll fluorescence imaging of cadmium-treated white cabbage plants

The chlorophyll fluorescence imaging technique is a valuable tool to study the impact of heavy metal stress in plants. The aim of this paper was to investigate the influence of Cd on photosynthetic apparatus of white cabbage (Brassica oleracea subsp. capitata f. alba) plants. Two cabbage cultivars ‘Ditmarska Najwcześniejsza’ (‘DN’; early) and ‘Amager Polana’ (‘AP’; late) were used. Cd was applied before planting seedlings (10 mg Cd kg DM of soil).. Measurements were performed at the 3rd leaf after 2 weeks of planting. The level of Cd-induced stress to plants was estimated by chlorophyll (Chl) content (photometrically) and analyses of images and numeric values of the major fluorescence parameters of Chl (Chl fluorescence imaging system FluorCam). Cd negatively affected the chlorophyll content and Fv/Fm, Fv’/Fm’, ɸ PSII and qP in leaves of early cultivar of white cabbage. However, in the case of late cv. we did not observe such distinct changes. It suggests that late cultivars. are more resistant to Cd than the early ones. Considering methodological aspect of the study, Chl fluorescence imaging can better reveal some alterations within the leaf, because numeric values of specific parameters, which are the averaged data collected from the whole leaf, cannot reflect the tissue specificity. Abbreviations: HM – heavy metal, Cd – cadmium, Chl – chlorophyll, Fv/Fm – photochemical efficiency of PSII in the dark-adapted state, F'v’/F'm’ – PSII maximum efficiency, ɸ PSII – quantum efficiency of PSII electron transport, NPQ – nonphotochemical quenching of maximal Chl fluorescence, qP – photochemical quenching coefficient.