Contribution of avoidance and tolerance strategies towards salinity stress resistance in eight C3 turfgrass species

Salinity is a potential environmental stress factor for plants. Improving plant growth under salinity stress requires an understanding of resistance mechanisms. Salinity stress resistance is related to both salinity avoidance and tolerance. In this study, interspecific differences in salinity stress resistance, avoidance, and tolerance were examined in eight C₃ turfgrass species, namely Agrostis alba, Agrostis tenius, Dactylis glomerata, Festuca ovina, Festuca rubra, Lolium perenne, Phleum pratense, and Poa pratensis. In a greenhouse experiment, plants were exposed to 50, 100, or 200 mM NaCl for 2 weeks supplied via a hydroponics system. We found that interspecific differences in salinity stress resistance were associated mainly with salinity tolerance. Salinity avoidance mechanisms also contributed significantly to stress resistance. The contribution of genotype towards interspecific variation in salinity resistance and tolerance was higher than that of Na⁺ concentration. Salinity stress had negative effects on shoot dry mass, water status, and membrane stability. Relative water content was significantly correlated with salinity resistance, avoidance, and tolerance, whereas no significant correlation was observed for ion leakage. Mineral contents showed no clear contribution to salinity tolerance. Species varied in their proline content even in control conditions, and there was a positive association between proline content and salinity resistance and tolerance, but a negative association between proline content and salinity avoidance. F. ovina and P. pratense displayed the highest and lowest salinity stress resistance, respectively. The results of this study suggest that both salinity tolerance and avoidance mechanisms contribute towards salinity resistance, and that variation in salinity stress resistance among species is attributed to differences in proline content.