The role of some metabolites on the osmotic adjustment mechanism in annual cutleaf medic [Medicago laciniata (L.) Mill] under drought stress

In order to study the role of some metabolites as proline, soluble sugar, soluble proteins and inorganic solutes on osmotic adjustment mechanism and variation of water relationship in cutleaf medic [Medicago laciniata (L.) Mill] under drought stress, a greenhouse experiment was conducted in 2004, at the Agricultural Biotechnology Research Institute, Karaj, Iran- using a factorial arrangement in RCBD with three replications. Two genotypes of cutleaf medic, sensitive and tolerant to drought stress was treated in four levels of water stress including: -0.1, -0.2, and -1 MPa as low, medium and high stress levels, respectively and normal condition (FC = -0.03 MPa). Results indicated that high stress decreased RWC of sensitive genotype. Increases in organic metabolites accumulation as Proline, soluble sugar and inorganic solutes as potassium were associated with a decrease in osmotic potential in tolerant genotype as compared to sensitive genotypes. This study revealed that osmotic adjustment, through increasing slouble sugar and potassium ion was considered as an important mechanism for drought tolerance in annual cutleaf medic, as in tolerant genotype, it was almost twice in comparison with sensitive genotype.