Growth response, carbohydrate and ion accumulation of diverse perennial ryegrass accessions to increasing salinity

Salinity stress inhibits plant growth and development. The objectives of this study were to investigate growth response, carbohydrate and ion accumulation of diverse perennial ryegrass (Lolium perenne L.) accessions under salinity stress and to determine phenotypic traits associated with variability in salinity tolerance. Ten diverse accessions of perennial ryegrass were grown in sand culture and exposed to a half-Hoagland solution amended with 0 (control), 50-, 100-, 150-, 200-, and 300 mM NaCl. Thirty-two simple sequence repeat (SSR) markers were used for examining genetic relationship among these accessions. Across all accessions, decreased plant height, K+ concentration and K+/Na+ and increased concentrations of fructan and Na+ were observed at ≥50 mM NaCl, while decreased leaf fresh and dry weight (DW), leaf water content (LWC), chlorophyll fluorescence (Fv/Fm), and increased water-soluble carbohydrate concentration (WSC) occurred at ≥150 mM NaCl. Principal component analysis revealed that DW, LWC, Fv/Fm, WSC and Na+ accounted for larger variation across salinity levels and accessions. Accession of PI275660 and BrightStar SLT were the most tolerant materials with less senescence of older leaf and were also genetically distinct from the highly sensitive accessions of PI231595 and PI251141. Percentage deceases in DW, LWC, Fv/Fm and increase in Na+ were larger for the sensitive PI231595 with increasing NaCl levels, compared to the tolerant PI275660. The maximum separations of salinity tolerance of accessions occurred at 200–300 mM NaCl. The results indicated that DW, LWC, Fv/Fm and Na+ could be associated with variability in tolerance of diverse perennial ryegrasses to high salinity stress.

► We examined the growth and physiological responses to increasing salinity.
► Decreased plant height and K+ and increased fructan and Na+ occurred at ≥50 mM NaCl.
► Decreased growth, LWC, Fv/Fm and increased WSC occurred at ≥150 mM NaCl.
► The tolerant accessions had less leaf senescence than that of sensitive accessions.
► DW, LWC, Fv/Fm and Na+ could be associated with variability in salinity tolerance.