Abstract

Kentucky bluegrass (Poa pratensis L.) (KBG) is the most commonly grown cool-season C3 turfgrass. However, as global temperatures rise, KBG struggles to tolerate higher temperatures, leading to increased irrigation demands--a growing concern in arid and semi-arid regions facing escalating drought conditions. In contrast, hybrid bermudagrass (HBG; Cynodon dactylon [L.] Pers. x Cynodon transvaalensis Burtt Davy), a warm-season C4 grass, has demonstrated promising adaptability in traditionally cool-season climates. Since 2008, HBG has been successfully grown with minimal winterkill in Provo, UT, USA, and is now being considered for broader adoption in similar climates. Two separate studies were conducted to evaluate the drought tolerance of HBG compared to KBG. The first study assessed two HBG cultivars, 'Latitude 36' (L36) and 'Tahoma 31' (T31), against a blend of KBG cultivars grown in a sand soil in a full factorial design with severe, mild, and no drought stress during the 2023 and 2024 growing seasons. As expected, KBG exhibited significant declines in NDVI, canopy cover, and visual turf quality under drought stress, with complete mortality occurring after ~six weeks of severe drought. In contrast, HBG maintained high performance under mild drought stress and showed only minor impacts under severe drought conditions by the third to sixth week. This suggests that HBG can sustain severe drought while maintaining acceptable turf quality. The second study expanded the evaluation by comparing KBG, six HBG cultivars ('Iron Cutter' [IC], 'Latitude 36' [L36], 'NorthBridge' [NB], 'OKC 1163' [O63], 'OKC 1666' [O66], 'Patriot' [PAT], and 'Tahoma 31' [T31])with its genetic parents, Common Bermudagrass (Cynodon dactylon [L.] Pers.) (CBG), African bermudagrass (Cynodon transvaalensis Burtt Davy) (AFB) in a loam soil. A single drought treatment of no irrigation was applied to all species and varieties, with four dry-down cycles across the 2023 and 2024 growing seasons. In the first year, KBG and CBG showed the poorest performance in NDVI, canopy cover, and visual turf quality ratings. HBG cultivars consistently ranked highest of all species across all measurements, but there was not much significant difference between cultivars. The HBG cultivars demonstrated strong drought tolerance and recovery compared to KBG and CBG. Findings from both studies suggest that HBG cultivars offer a promising, water-efficient alternative to KBG in semi-arid, cool-season regions experiencing increasing water scarcity.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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