Physio-morphological and biochemical responses of dixie grass (Sporobolus virginicus) to NaCl or Na2SO4 stress

Salinity, one of the most detrimental abiotic stresses, reduces growth, development, biomass, and yield of economically important plant species. Dixie grass (Sporobolus virginicus) is a halophytic, perennial C4 grass that quickly adapts to the coastal saline area and is generally used worldwide as fodder for grazing animals. However, studies have hitherto not investigated the physiological and biochemical basis of salt tolerance in dixie grass. The objective of this study was to evaluate the physiological, morphological, and biochemical responses of dixie grass to different levels of salinity (0, 400, 600, and 800 mM NaCl or Na2SO4) under greenhouse conditions. Overall growth traits of dixie grass were significantly reduced, especially in plants exposed to 800 mM Na2SO4. Leaf area of the plants was reduced by 78.49% and 54.52% over the control at 800 mM Na2SO4 and 800 mM NaCl, respectively. Na+ content in the leaf tissues of Na2SO4-treated plants was enriched by 28.88 folds over the control, causing chlorophyll degradation, diminution of photon yield of PSII, and reduction in the net photosynthetic rate. Greater accumulation of free proline and total soluble sugars in plants exposed to Na2SO4 were evident, which might be responsible for the osmotic adjustment. Alternatively, Na+ crystal secretion in dixie grass reduced ion toxicity, especially in the leaf blade. The study demonstrated that dixie grass counteracts the salt-induced ionic imbalance by modulating biochemical, physiological, and morphological attributes.