THE PHYSIOLOGICAL RESPONSE TO WATER STRESS OF SOME HYGROPHILOUS PLANT SPECIES FROM THE SOUTHWEST OF ROMANIA

Abstract

This work investigates the physiological responses of hygrophilous plants from southwestern Romania to water deficit conditions. The study quantifies variables such as stomatal conductance, osmotic potential, chlorophyll content, photosynthetic activity and osmolyte accumulation, to understand the mechanisms of tolerance and the capacity to recover from stress. The results will
provide information on the vulnerability of hygrophilous species in the context of climate change and will propose directions for the conservation and management of wetland habitats. Two hygrophilous species, Petasites kablikianus and Telekia speciosa, were included in this study due to their ecological significance and sensitivity to water availability. Both species are characterized
by large stature and high photosynthetic efficiency under conditions of normal soil moisture, reflecting their adaptation to consistently humid habitats. However, when water levels decrease and a water deficit is established, these species exhibit pronounced reductions in key physiological processes, most notably in photosynthetic activity. This decline is associated with stomatal closure, reduced CO₂ assimilation, and limitations in photochemical efficiency, all of which are common responses to water stress in moisture-demanding plants. Moreover, prolonged exposure to suboptimal water availability can lead to osmotic stress, reduced turgor, and potential cellular damage, compromising overall plant growth and survival. The observed sensitivity of P. kablikianus and T. speciosa to declining soil humidity highlights their vulnerability in the face of habitat alteration, suggesting an increased risk of maladaptation in environments that no longer provide stable water conditions. These findings emphasize the importance of monitoring hydric changes in wetland and riparian ecosystems, particularly in the context of climate variability