Evaluation of salt tolerance in common bean genotypes by ion regulation and searching for screening parameters

The objectives of this work were (1) to screen large collection of bean genotypes for salinity responses and (2) to identify the best traits for screening the bean germplasm in tolerance to salt stress. Sixty-four bean genotypes were subjected to 125 mM NaCl. Plants were grown in hydroponic growing medium in greenhouse. The screening was carried out at early growing stage (25 days old plant). Ion regulation mechanisms were studied to identify the selection traits which would facilitate fast, effective and reliable screening for salinity tolerance. The genotypes tested showed a wide range of variability in tolerance to NaCl treatment. They were classified as 5 genotypes being tolerant, 43 mild tolerant and 16 being sensitive. Among the traits which were tested shoot Na concentration and shoot Na/K and Na/Ca ratios can be reliable indicators for rapid selection of bean genotypes at young stage of plant growth. However, shoot Cl concentration was not associated with salt tolerance of bean plant. Shoot and root dry weights in tolerance to NaCl stress could be significant but in a lesser extent than Na concentration and Na related ratios with K and Ca.