bulk elastic modulus, Phaseolus vulgaris L., pressure-volume curves, water potential, water stress.
Abstract
The effects of water stress on water relations in the leaves of young common bean (Phaseolus vulgaris L.) plants were studied. Water stress was imposed 14 days after the emergency by withholding water until soil water potential reached -0.9 MPa. Water defi cit led to a noticeable decrease in both the osmotic potential at full hydration and turgor loss poin in the primary and the fi rst trifoliate leaves of all the cultivars. The lowest calculated values for osmotic adjustment
are found in droughted plants of cv. Dobrudjanski ran (-0.29 MPa for the primary and -0.42 MPa for the fi rst trifoliate leaf). In contrast, high osmotic adjustment was found in cultivars Plovdiv 10 and Prelom. The three bean genotypes displayed signifi cant differences in their adaptive response to drought. This study indicated that osmotic adjustment is one of the major adaptive mechanisms of Phaseolus vulgaris to survive drought. The main difference among cultivars appears to be due to turgor maintenance, which may be more representative of the physiological status of the leaves in these cultivars.
