b'To determine performance in multiple regions, elite experi- A warming climate is favorable to expanding turf bermudag-mental lines must be tested in as many states as possible andrass use to the north. However, the changing climate has a large over multiple years. That multi-location, multi-year testing is, notvariability between seasons and among years. Some winters surprisingly, very expensive.in the transition zone or northern sites could be harsh to ber-There are more challenges, too. mudagrass. To encounter the variability of winter weather, cold While there are many popular species of turfgrass, amonghardiness is still an important trait in new cultivars targeted to the most desirable is bermudagrass, which happens to be Wusthe regions, Wu says.breeding specialty. A naturally warm season turfgrass, bermu- Wus colleague, OSU professor and turfgrass research/exten-dagrass cultivars are grown extensively on home lawns, sportssion specialist Dennis Martin says the unpredictability of todays fields and golf courses in tropical, subtropical and transition cli- weather, including that caused by climate change, is the single mates. Bermudagrass is a cross-pollinated species. The genomebiggest challenge to bermudagrass cultivation.of the grass carries many undesirable genes through a geneticThe extremely rapid changes that we might see in weather mechanism called dominance. This makes weeding out less posi- are arguably the greatest threat [to bermudagrass]. Plants use tive traits very difficult, as bermudagrass is highly self-infertilea combination of both daylength and temperature to acclimate. and must outcross to another genotype of its species to repro- When your day lengths are short, but your temperature sud-duce by seed.denly goes into a fall or late summer condition when it should Due to its significant inbreeding depression in the species, itbe cold, those plants can lose some of their cold hardiness, or is extremely challenging to remove an undesirable or deleteriousdeacclimate, he says. gene from the genome, says Wu. Therefore, the breeder hasThis deacclimatization thing scares the heck out of me, much less control over genetic improvement relative to majorMartin adds. Significant wild swinging weather events are an food crops, which have inbreeding systems established. immense threat. What Dr. Wu and his team are asked to do is not Selecting for specific traits is equally challenging. only have great winter tolerance and great summer tolerance From the genetic standpoint, each of the [desirable] traits isand excellent drought resistance and water use efficiency, but controlled by numerous genes. Hence, it is quite a challenge toalso people want late season color under chilly conditions and pull these desirable traits together into one grass, he explains. short-day lengths, and then theres acclimation too, which is the next great challenge. Its a lot of demands.Breeding for todays new challengesThe OSU program generates a large volume of new plantsinSuccess despite challengesthe range of 10,000 to 60,000 genetically unique plants perSince the 1950s, scientists at OSU have collected a large number yearthrough breeding efforts. These plants are screened,of bermudagrass plants and seed samples from around the tested, and characterized by a team of interdisciplinary staff andworld, including from across Africa, North America, South students.America, Asia, Europe, and Oceania. The globally distributed, New cultivars need to combine high turf quality and othernatural bermudagrass germplasm collections provide enor-desirable traits (resistance/tolerance to abiotic and biotic stress)mous genetic variation for breeding work. From this germplasm, and as many positive production traits as possible. But theresthe OSU team has developed 10 commercially released cul-more: given significant water shortage pressures in many statestivars: Midlawn and Midfield (joint releases with Kansas State today, the cultivars also have to offer improved drought resist- University) in 1991, Yukon in 1996, Riviera in 2000, and Patriot in ance and water use efficiency.2002. In 2010 the team released OKC1119 sold as Latitude 36 Over the past 15 years, the OSU breeding program has beenand OKC1134 sold as NorthBridge. The most recently released a participant in a collaboration between eight southern U.S.(2017) and commercialized product from the OSU program turfgrass breeding programs. The major goal of the collaborationis OKC1131, sold as Tahoma 31.OKC3920 and OKC1876 were is to improve drought resistance and water use efficiency in fourreleased 2022 but are not yet commercialized. important warm season turfgrasses, including bermudagrass.Martin says there have been major and continued advance-Drought resistance is a top priority trait we have focused onments over the past 30 years in all individual performance traits, in turf bermudagrass cultivar development since 2010, says Wu.from attributes like fine texture, dark green color, high density Our breeding and testing pipeline is full of experimental linesand uniformity, to traits like freeze tolerance.with improved drought resistance. A few best products will rollOSUs releases have enjoyed commercial success and have out to the market to save irrigation water substantially in the nearbeen produced on more than 60 sod farms in the U.S., Australia, future.Brazil, Spain, Italy, Portugal, Turkey, Greece, Vietnam, Japan, and The changing climate means OSUs bermudagrass cultivarsChina. In the U.S. alone, they are produced in 18 states and used are being planted further and further north each year. Thatin 26 states. might work if climate change was a consistent warming trend.Of OSUs successes to date, Tahoma 31 is arguably its most However, its not.important.OCTOBER 2023SEEDWORLD.COM /11'