effect of trinexapac-ethyl on the quality and physiological constituents of perennial ryegrass (lolium perenne l.) in the salinity conditions

turf is one of the most important ground covers and it is one of the main elements ofurban landscape design. plant growth regulators, such as growth inhibitors, are widelyused in turfgrass management to suppress shoot growth and inflorescences production.this experiment was conducted to determine the interactive effects of trinexapac-ethyl(te) and salinity on the growth, visual quality, and chemical constituents of perennialryegrass (lolium perenne l.). plants were grown hydroponically under four levels ofsalinity (1.5 (control), 2.5, 5.0 and 7.5 ds/m) and three levels of trinexapac-ethyl (0,0.02, and 0.04 g/m2). the results showed that growth rate of perennial ryegrassdecreased significantly with both trinexapac-ethyl and salinity treatments, although thedifferences in growth rate were not significant between trinexapac-ethyl treatments at0.02 and 0.04 g a.i./m2 application rates. root penetration depth, fresh and dry weightsincreased by trinexapac-ethyl, while salinity decreased them. the results showed thattotal chlorophyll, chlorophyll a, chlorophyll b, and proline concentrations increased byapplication of trinexapac-ethyl, while te had no significant effect on the carotenoidcontent. salinity treatment decreased total chlorophyll, chlorophyll a, chlorophyll b, andcarotenoid content, but increased proline concentration. overall, it can be suggested thatfor improving the tolerance of perennial ryegrass to salinity up to 2.5 ds/m and reducedmowing frequency, the turf should be sprayed monthly with te at 0.02 g/m2.