Abstract

The effect of salinity stress during germination, early seedling and vegetative growth on morphological and biochemical traits was evaluated for 18 genotypes of common bean (Phaseolus vulgaris L.) at 0, 60, 120, and 180 mM NaCl. Analysis of variance showed that the salinity stress had significant effect on all traits except shoot to root length and dry weight ratios. Though salinity stress delayed germination in all accessions, three local landraces, ‘Naein’, ‘Lordegan’ and ‘Talash’ germinated fastest under high salinity (120 mM NaCl). The Na uptake among the cultivars studied suggested that ‘COS-16’ (1.12 mg/g) and ‘Naein’ (1.07 mg/g) were most tolerant to salinity. Conversely, ‘Cardinal’ (1.89 mg/g) and ‘Talash’ (1.89 mg/g) that had the highest Na uptake were considered as the most susceptible cultivars. Seeds that germinated rapidly at 60 mM NaCl also germinated rapidly at 120 mM NaCl. At 180 mM NaCl, several accessions reached 50% germination by 6 days, dem­onstrating high genetic potential within P. vulgaris for salinity toler­ance during germination. The biomass of radicles plus hypocotyls decreased with increasing salinity. Cluster analysis separated the ac­cessions into three groups. Group I included salt sensitive accessions with late germination, high sensitivity index, and reduced seedling growth. Group II included salt tolerant accessions with rapid germina­tion, high sensitivity index, and enhanced seedling growth. Group III only included cultivated accessions corresponding to the CIAT gene pool with rapid germination, low sensitivity index, and intermediate seedling growth.

Key words: Phaseolus vulgaris L., salinity stress, Na⁺ ions, morphological and biochemical traits.