Evaluation of salt tolerance in 41 pigeon pea varieties during germination

In this study, we identified the salt tolerance of 41 pigeon pea (Cajanus cajan) germplasm varieties during the germination period. Furthermore, we identified 10 physiological response indicators, including germination rate, germination index, vigor index, root surface area, and root volume. Principal component, membership-function, and cluster analyses were used to comprehensively evaluate salt tolerance during the germination period. Concurrently, the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities in the seedlings were determined, and the physiological response mechanisms of different salt-tolerant pigeon pea seedlings under salt stress were analyzed. The results revealed significant differences in the salt tolerance of 41 pigeon pea germplasm varieties during germination, with relative root length, crown ratio, germination index, and average diameter being selected as the key indices of germination salt tolerance. Cluster analysis based on membership-function values divided the 41 pigeon pea germplasm varieties into four categories, namely highly salt tolerant (1 variety), salt tolerant (10 varieties), intermediate tolerance (23 varieties), and salt-sensitive (7 varieties). Ultimately, using pigeon peas that exhibit varying levels of salt tolerance, we reveal that the cytoplasmic membrane permeability and enzyme viability of high-salt-resistant and salt-resistant varieties generate superior physiological responses compared to salt-sensitive varieties.