WATER STATUS AND STRESS-MEMORY FORMATION IN PHASEOLUS PLANTS WITH DIFFERENT DROUGHT RESISTANCE POTENTIAL.

The results of the investigations about the impact of repeated stress on the plant water status have been analysed by taking the literature information about some mechanisms, associated with the stress-memory formation and resistance of plants to drought. The concept of stress-memory existence as an ability of quick and adequate plant response to recurring stress exposure (it is stated that reaction of plants affected by repeated stress differs from the reaction of plants, exposed to stress factors for the first time) was experimentally demonstrated. It was established that beans plants of the species Phaseolus lunatus, L., variety ?Fetanisa?, Phaseolus acutifolius, Gray, variety ?Acutifolius 5? and Phaseolus vulgaris L., variety ?Nina?, which have been undergone a mild drought condition at phase "first trifoliate leaf" more easily supports repeated stress to the stage of "flowering- pods formation" as a result of the formation of stress memory - the ability to react appropriately to the unfavorable factor. The dependence of stress-memory formation on homeostatic water capacity in tissues and on the constitutive resistance of the genotype have been demonstrated. The self-regulation of water status by increasing water retention capacity and preserving turgescence are nonspecific mechanisms important for stress-memory formation and plant adaptation to fluctuating humidity conditions and water stress recurring over time.