Variable impacts on growth of deficit irrigation on Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt Davy and Poa pratensis L

Abstract As average global temperatures rise, Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt Davy (triploid interspecific hybrid bermudagrass; HBG) may be increasingly suited for traditionally cooler climates where Poa pratensis L. (Kentucky bluegrass; KB) is common. The objective of this study is to evaluate growth for two HBG cultivars (‘DT‐1’ and ‘NorthBridge Turf Bermudagrass’) compared with KB in all combinations of deficit, moderate, and high irrigation. The HBG had significantly more shoot and root biomass and root depth than KB, with the latter having a higher shoot to root ratio. Differing responses to deficit irrigation were also observed between the two HBG cultivars. When drought stressed, NorthBridge Turf Bermudagrass seems to send roots deeper into the soil to capture the water stored there while DT‐1 grows thicker masses of roots at a shorter depth to maximize its ability to capture water near the surface. These data provide a direct comparison of HBG and KB—quantifying the response for root and shoot growth under deficit irrigation when grown under cool‐season conditions. These data suggest that irrigation needs, especially in regions with increasing water scarcity, will likely be less for HBG than KB as a function of more extensive root systems.