The Mitigative Effect Of Saltinity Stress Under Elevated CO₂ On Bermudagrass

Bermudagrass?Cynodon dactylon?has a good ability of heat and drought resistance,with good recovery speed and turf quality,it is the most widely-used turfgrass species in the climate transition areas.Bermudagrass is used as public green land,playground and vegetation restoration of ecologically fragile land,but is sensitive to salinity stress.Salinity stress leads to physiological and metabolic disorder,ion balance destruction,growth inhibition,thus affecting the lawn quality.That discuss the ways and measures to alleviate salinity stress of turfgrass can contribute to better play to the environmental governance functions on the salinization of soil environmental.Greenhouse gases brings on the side effects to global climate change,as the same time we assume that the increase of ambient CO₂ concentration plays a positive and active role on enhancing the stress-relieving of turfgrass,and can ease the salinity stress of turfgrass.Accordingly,this study based on hybrid bermudagrass 'Tifway' as materials under 200mM NaCl salinity stress,atmospheric CO₂ concentration with well watered as CK,to explore the influence of bermudagrass leaf on physiological activities,osmotic adjustment and/or ion?Na⁺ and K⁺?balance under the treatment of ambient CO₂ concentration(400?mol·mol^-1)and elevated CO₂ concentration(800 ?mol·mol^-1).The main results are as follows:1.Compared with ambient CO₂ concentration,Bermudagrass under elevated CO₂ concentration of salinity stress improved significantly in turf quality?TQ?,net photosynthetic rate?Pn?,transpiration rate?Tr?,stomatal conductance?gs?,cellular Room CO₂ concentration?Ci?and cell membrane stability,by 28 d,TQ improved 13%,Pn improved 31%,Ci increased by 78%,cell membrane stability increased by 22%;and transpiration rate?Tr?,stomatal conductance?gs?decreased significantly,respectively decreased by 42%and 13%.2.Compared with ambient CO₂ concentration,the content of soluble sugar,proline,betaine?GB?and soluble protein increased significantly in Bermudagrass under elevated CO₂ concentration of salinity stress,by 28 d,proline content increased by 23%,GB was increased by 12%.3.Compared with ambient CO₂ concentration,Bermudagrass under elevated CO₂ concentration of salinity stress,by 28 d,its Na⁺ content decreased by 23.7%,while K⁺content and K⁺/Na⁺ ratio had no significant effects.Elevated CO₂ concentration increased TQ,RWC,Pn and cell membrane stability,which may be related to accumulation of soluble sugars,proline,and glycine betaine?GB?under salinity stress,and promoted osmotic adjustment,meanwhile suppressed Na⁺ absorption,but had no significant effects on K⁺ and the ratio of K⁺ to Na⁺.Elevated CO₂ concentration mitigated significantly salinity stress.Our results demonstrated that elevated CO₂ concentration was effective in alleviating physiological damages of salinity stress in bermudagrass,suggesting that bermudagrass may benefit from the rising atmospheric CO₂ concentration associated with global climate changes.