Genotypic Variations in Plant Growth and Nutritional Elements of Perennial Ryegrass Accessions under Salinity Stress

Perennial ryegrass ( Lolium perenne ) is a popular cool-season and forage grass around the world. Salinity stress may cause nutrient disorders that influence the growth and physiology of perennial ryegrass. The objective of this study was to identify the genotypic variations in growth traits and nutrient elements in relation to salinity tolerance in perennial ryegrass. Eight accessions of perennial ryegrass [PI265351 (Chile), PI418707 (Romania), PI303012 (UK), PI303033 (The Netherlands), PI545593 (Turkey), PI577264 (UK), PI610927 (Tunisia), and PI632590 (Morocco)] were subjected to 0 (control, no salinity) and 300 m m NaCl for 10 d in a greenhouse. Across accessions, salinity stress decreased plant height (HT), leaf fresh weight (LFW), leaf dry weight (LDW), leaf water concentration (LWC), and concentration of N, C, Ca 2+ , Cu 2+ , K + , Mg 2+ , and K + /Na + ratio and increased Na + concentration. Negative correlations were found between C and Na + , whereas positive correlations of K + /Na + with C and N were found under salinity treatment. The principal component analysis (PCA) showed that the first, second, and third principal components explained 40.2%, 24.9%, and 13.4% variations of all traits, respectively. Based on loading values from PCA analysis, LWC, Na + concentration, and K + /Na + ratio were chosen to evaluate salinity tolerance of accessions, and eight accessions were divided into the tolerant, moderate, and sensitive groups. The tolerant group had relatively higher LWC and K + /Na + ratio and concentrations of C, P, and Fe 2+ and lower Na + concentrations than the other two groups, especially the sensitive groups. The result suggested that lower Na + accumulation and higher K + /Na + ratio and LWC were crucial strategies for achieving salinity tolerance of perennial ryegrass.