Preliminary studies on some chlorophyll fluorescence parameters in Crassulaceae species of different leaf characters under water stress

Chlorophyll fluorescence quenching parameters of ABSTRACT Kalanchoe daigremontiana, K. fedtschenkoi cv. marginata, K. tomentosa, Crassula multicava and Cotyledon ladysmithiensis were compared in well watered and water deficient plants. The maximum quantum yield (Fv/Fm) of photosystem II (PSII) proved to be a very stable parameter in all species and water treatments. The EQY, NPQ, qP and ETR differed in Crassula multicava from those of the other plants. The allocation of absorbed light by PSII that is utilized to photosynthetic electron transport and thermal dissipation was also calculated. Analysis of the chlorophyll fluorescence parameters demonstrated, that Crassula multicava was the only plant, which exhibited a higher proportion of excitation energy allocated to PSII photochemistry under water deficit at 1200 µmol m-2s-1 actinic light (AL) intensity