Field and Laboratory Evaluation of African Bermudagrass Germplasm for Freezing Tolerance.

Bermudagrass (Cynodon spp.) is widely used for golf courses, athletic fields, and home lawns in the southeastern United States for its superior turf quality and excellent durability. While the grass is considered to have excellent heat and drought tolerances, its ability to survive freezing temperatures is low. Development of cultivars with enhanced adaptation to freezing temperatures would constitute a significant improvement in the management of bermudagrass in the transition zone. Interspecific hybridization of African and common (C. dactylon) bermudagrasses has been used with tremendous commercial impact in bermudagrass breeding. Selection of appropriate African bermudagrass parents would aid in the development of cold tolerant bermudagrass cultivars. A trial was established at the Lake Wheeler Turfgrass Field Laboratory (Raleigh, NC) in July 2010 in order to evaluate a set of African bermudagrass accessions from the USDA germplasm collection for their cold tolerance. Four commercial cultivars (‘Patriot’, ‘Quickstand’, ‘Tifsport’, and ‘Tifway’), reported in the literature for having low freeze tolerance values, were included as checks. Winter-kill and spring green-up were measured 2011-2015. High levels of cold tolerance were observed among the African bermudagrass germplasm. Plant introductions 290905, 647879, 647880 and 647881 were the top performers with similar or better cold tolerance than the controls. In addition to the field data collected, controlled freeze tests were conducted to corroborate field results while developing a means for quickly screening additional germplasm or progeny for an existing crossing program. Overall, results indicate that these plant introductions can be used as additional sources of cold tolerance in bermudagrass breeding.