Heat stress is a major factor limiting growth of cool-season grass species.  Heat stress  causes the imbalance of photosynthesis and respiration, due to decreases in photosynthetic production of carbohydrates and increases in respiratory consumption of carphydrates with increasing temperatures, which can lead to carbohydrate depletion following prolonged periods of heat stress. Controlling respiratory consumption of carbohydrates or respiratory acclimation to increasing temperatures is important for efficient carbohydrate utilization that regulate the survival of heat stress in cool-season grass species. Roots of thermal Agrostis scabra plants are able to grow and survive at soil temperatures as high as 40 C while common cool-season grass species, such as Agrostis stolonifera, root mortality increases dramatically as tmeperatures above 25 C. The superior root thermotolerance of thermal A. scabra was found to be associated with greater respiratory acclimation potential to increasing temperatures and lower maintenance respiration rate, and more efficient allocation of carbon for root growth.