Changes in Activity Profile of Some Antioxidant Enzymes in Alfalfa Half-sib Families under Salt Stress

In order to evaluate salt (NaCl) tolerance in alfalfa (Medicago sativa L.) half-sib families, a factorial experiment on the basis of completely randomized design, with 20-25 individuals in pot (replicates) was carried out under field conditions at the Research Station of University of Tabriz. Electrophoretic analyses were performed by using 7.5% slab polyacrylamide gels. Two antioxidant enzymes including superoxide dismutase (SOD) and peroxidase (POX) and one common isozymic system namely esterase (EST) were stained and for each isozymic band the "density x area" scores onto gels were evaluated by MCID software as enzymatic activity. Plant materials consisted of 12 half-sib families that were obtained from a "polycross nursery progeny test" in the same station, a few years ago. The applied salt stress (9 +/- 0.2 ds m(-1)) reduced plant height, dry weight, leaf weight and stem weight about 31.7, 37.5, 33.7 and 34.7 percent, respectively. Significant correlations were observed between plant height and some antioxidant isozyme activities. Salt stress increased activities of some SOD and POX isozymes but it was ineffective on the activity of EST. Among the families, Ranger cultivar and Zaghl-aghaj and Taze-kand landraces which displayed maximum height and other characteristics exhibited the highest increments in respect of isozyme activities, indicating that antioxidant analysis by gel electrophoresis could be a useful tool for salt stress tolerance studies.