Growth response and ion regulation of seashore paspalum accessions to increasing salinity

• Significant variations of salt tolerance existed among Chinese seashore paspalums.
• Salinity stress significantly influenced leaf firing, shoot and root growth.
• Salinity stress reduced K+ concentration and increased Na+ concentration.
• Ion regulation relies on maintaining high K+ and low Na+ concentration in shoots.

Seashore paspalum (Paspalum vaginatum Swartz) is an important warm-season turfgrass indigenous to tropical and coastal areas worldwide. The objectives of this study were to investigate the growth response and ion regulation of Chinese seashore paspalum germplasm under salinity stress. Twenty-seven seashore paspalum accessions and one check cultivar “Sea Isle 2000” were grown in solution culture in a glasshouse, with NaCl added to achieve salinities of 0 (control), 340 and 510 mmol/L. Compared with the nonsaline controls, the salinity stressed accessions showed significantly increased leaf firing, decreased shoot growth, and an increase or decrease in root growth. Significant genetic variations in the leaf firing (LF), relative shoot weight (RSW) and relative root weight (RRW) were found among the different accessions, with coefficients of variation ranging from 19.54% to 37.84%. The P40 accession had the best salinity tolerance with little leaf firing under salinity stress, followed by Sea Isle 2000, P29 and P14. For the control, the average K+ concentration was 1161.69 mmol/kg in the shoots and 383.73 mmol/kg in the roots. Compared to the control, the salinity treatment showed that the K+ concentration treatment decreased in both the shoots and roots; however, the percentage of the reduction in the shoots was significantly lower (26.20%) than that in the roots (69.68%). The Na+ concentration was very low in both the shoots and roots of the seashore paspalum, with an average of 65.90 mmol/kg and 39.50 mmol/kg, respectively, under the treatment of nonsalinity. Compared to the nonsalinity control, the Na+ concentration greatly increased in both the shoots and roots; however, the percentage of the increase in the shoots was lower (15-fold) than in the roots (25-fold). The results indicate that taking up more of the K+, maintaining a high K+ concentration in the shoots and reducing the Na+ being transferred from the roots to the shoots could be the mechanisms for Na+ and K+ regulation for salinity tolerance in seashore paspalum.