Assessment of changes in photosystem II structure and function as affected by water deficit in Amaranthus hypochondriacus L. and Amaranthus hybridus L.

► Adaptive behaviour of the functional and structural parameters of PSII was measured. ► Changes occurred in PSII functioning in both amaranth species studied. ► A. hybridus proved to adapt efficiently resulting in rather a low loss of PSII function. ► A. hybridus also maintained a higher RWC during severe drought stress. ► Specific photosynthetic kinetics could be used to identify traits of drought tolerance.