Screening of cool season turfgrass species and varieties for tolerance to simulated ice encasement

Abstract Ice encasement (IE) is one of the big challenges in winter stress management on golf course putting greens in Northern Scandinavia. The turfgrass is damaged due to lack of oxygen (hypoxia or anoxia) and accumulation of toxic by‐products of anaerobic respiration. Breeding IE‐tolerant turfgrass species and varieties is the best defense against these challenges. A method to simulate ice encasement was tested to screen selected varieties of winter‐hardy bentgrass species and red fescue subspecies. Note that 32 varieties were chosen from the SCANGREEN trial seeded at NIBIO Landvik, Norway, in 2019. Samples were taken in December 2020, 2021, and 2022, vacuum sealed in plastic, and stored in darkness at 0.5°C for up to 77 days to test them for their tolerance to simulated ice encasement (SIE). Samples were incubated at different intervals; plants were potted, and tiller survival was tested after 4 weeks of regrowth. Lethal duration of ice encasement (LD 50 ) that is, the number of days under anoxia that kills 50% of the plant population for each species and variety was calculated. The results showed that the ranking of cool season turfgrass species for tolerance to SIE was velvet bentgrass > Chewings fescue > slender creeping red fescue = colonial bentgrass > creeping bentgrass. This ranking does not fully reflect the ranking found in field tests where velvet bentgrass was superior together with creeping bentgrass. SIE caused a more rapid development of anoxia than IE in the field, and we hypothesize that creeping bentgrass is less tolerant to these conditions compared to the other species tested. To make the SIE method more representative for IE in field, it should be further adapted with incubation at lower temperatures, and with acclimation conditions to be standardized prior to sampling. Within species, the best tolerance to IE was found in velvet bentgrass Nordlys, creeping bentgrass Penncross, Chewings fescue Lykke, and slender creeping red fescue Cezanne.