Salinity Tolerance of Kentucky Bluegrass as Affected by Salicylic Acid

Salinity is one of the greatest environmental challenges facing plant growth and development in the 21st century. Salicylic acid (SA) is a phenolic compound and signal molecule involved in the regulation of plants responses to biotic and abiotic stresses. This greenhouse experiment was conducted to determine effects of SA application on Kentucky bluegrass (Poa pratensis L.) responses to salinity stress. The three salinity levels (0, 40 and 80 mM NaCl) were applied in nutrient solutions, and foliar SA treatments (0, 1 and 2 mM) were applied at 2-weeks intervals. The study was carried out as a factorial experiment based on completely randomized experimental design with four replications. Salinity reduced root and shoot dry weight, visual turf quality, leaf chlorophyll and potassium content, whereas electrolyte leakage, proline and sodium content were increased with salt concentration in nutrient solution. Salicylic acid application ameliorates adverse effects of salinity in all factors and this effect was more pronounced in 80 mM NaCl. In terms of root dry weight, leaf sodium and proline content as well as electrolyte leakage, SA application at 2 mM had better results than 1 mM. These results suggest that further studies are required to find proper SA application rate in different salinity levels.