Pigeon pea (Cajanus cajan L.) is a vital legume crop cultivated in tropical and subtropical regions, is impacted by salinity stress. It is a major abiotic stress caused by excessive salt accumulation in soil, severely affects crop growth and physiological processes. This study evaluated 99 pigeon pea genotypes sourced from ICRISAT for their salinity tolerance at the germination and seedling stages under six treatment conditions: control (0 mM NaCl), hydropriming, and four salinity levels (50, 100, 150, and 200 mM NaCl). The growth parameters including germination percentage, root length, shoot length, fresh weight, dry weight, and vigour index were recorded to assess stress responses. The experiment was conducted under a completely randomized design with four replications and data analysis employed Principal Component Analysis (PCA) and dendrogram clustering. PCA revealed that salinity stress negatively impacted most growth parameters, with genotype that express variation at higher NaCl concentrations. The genotypes G5(ICP2947), G3 (ICP 7380), G20 (ICP 14961), G2 (ICP 7024), and G10 (ICP 16184) consistently performed well, showing higher germination, vigour index, and seedling lengths, indicating strong tolerance. Dendrogram analysis clustered genotypes into distinct tolerance groups. Germination percentage and vigour index values are subjected to dendrogram analysis, because these parameters are the key components of assessing the salt tolerance in seedling stage. Two clusters were formed for the germination percentage parameter and four distinct clusters were formed for the vigour index of the seedlings. Overall, the study identified key pigeon pea genotypes with significant salinity tolerance, which are promising genotypes for inclusion in breeding programs targeting salt-affected regions

Pigeon pea, germination percentage, vigour index, principal component analysis, dendrogram clustering

The present study evaluated the salinity tolerance of 99 pigeon pea (Cajanus cajan L.) genotypes under varying levels of NaCl stress using morphological parameters at the germination and seedling stages. The findings revealed significant genotypic variation in response to salinity, with increased salt concentrations leading to a general decline in germination percentage, shoot and root length, fresh and dry weight, and vigour index. Principal Component Analysis (PCA) effectively computed the variability and highlighted the key growth parameters contributing to salt tolerance across different salinity treatments. Genotypes such as G5 (ICP 2947), G3 (ICP 7380), G20 (ICP 14961), G2 (ICP 7024), and G10 (ICP 16184) consistently demonstrated superior performance under saline conditions, indicating their potential for tolerance and adaptability. Dendrogram clustering further categorized the genotypes into tolerant, moderately tolerant, and sensitive groups, providing a clearer understanding of genotype performance and aiding in selection for breeding programs. The integration of PCA and dendrogram clustering approaches provided a robust framework for identifying salt-tolerant genotypes. These tolerant lines offer valuable genetic resources for the development of pigeon pea varieties suited to salt-affected regions, contributing to improved crop productivity and resilience in marginal environments

Susi Sivakumar, Mahendran Ramachandran, Vinothini Nedunchezhiyan, Thirugnanakumar, Mohanasundaram Sugumar and Sathees Kumar Kathirvel (2025). Principal Component and Cluster Analysis for Salinity Tolerance in Pigeon pea Genotypes (Cajanus cajan L.). Biological Forum, 17(7): 135-141