Physiological Responses and Gene Expression of Kentucky Bluegrass Under Salt Stress.

Understanding the response of salt stress under salinity condition is important to find a good way to improve turfgrass salt tolerance for turf management. The objective of this study was to examine physiological responses and gene expression of Kentucky bluegrass (Poa pratensis L.) that vary in tolerance to salinity stress. Salt-tolerant entries PI 371768 and PI440603 and salt-sensitive entries Midnight and Brilliant were exposed to 4 levels of salinity: 0 ds m-1 (control), 6 ds m^-1, 12 ds m^-1, and 18 ds m^-1. Acclima Digital TDT soil moisture sensors were buried in the pots to read soil volumetric water content, temperature, permittivity and bulk conductivity. Turf quality, stomata conductance, and leaf water potential decreased, while the electrolyte leakage increased under salinity stress (6 ds m^-1, 12 ds m^-1, 18 ds m^-1) for all accessions. Midnight exhibited greater changes in all measurements compared to 768, 603, and Brilliant. The 6 ds m^-1 treatment had little effect on the accessions. Interestingly, Brillant showed higher stomatal conductance and turf quality than all other entries, but electrolyte leakage and leaf water potential indicated that it was salt intolerant. Gene expression under salt stress will also be discussed.