Variability in Creeping Bentgrass Cultivar Germinability as Influenced by Cold Temperatures

Abstract

Core Ideas Golf course superintendents often overseed winter‐damaged areas with creeping bentgrass in the early spring when temperatures are not ideal for rapid germination. Typical spring temperatures in the upper Midwest were used to define treatments in a controlled environment study to determine general germination response from early April to late May. Response was measured across 21 cultivars to find those with superior germinability under suboptimal conditions. The study found that creeping bentgrass does not germinate below 45°F. At temperatures typical to mid‐April, the cultivars Proclamation, Declaration, and Pure Select had the best germinability. Re‐establishing creeping bentgrass greens after winter damage can be a significant challenge in cold climates. Golf course superintendents require creeping bentgrass (Agrostis stolonifera L.) cultivars that are able to germinate under suboptimal temperatures to ensure early spring play. Little is known about cultivar differences for cold temperature germination; therefore, we assessed the germinability of 21 creeping bentgrass cultivars in a controlled environment. Temperature treatments represented a range of spring temperatures in Minnesota from 7 April to 25 May. Germination began occurring at the 19 April treatment. Top‐performing cultivars included Proclamation, Declaration, and Pure Select while Independence and Memorial performed poorly. Overall, we found that temperatures below 45°F do not allow for sufficient creeping bentgrass germination regardless of cultivar. There were few relevant differences for the 25 May treatment. Golf course superintendents should carefully consider cultivar differences when seeding at suboptimal temperatures.

Soil Temperature Mediated Seedling Emergence and Field Establishment in Bentgrass Species and Cultivars during Spring in the Northeastern United States

“…No velvet bentgrass cultivar was ever observed to be in the top statistical performance group, along with 'Declaration' and 'L-93' creeping bentgrass and 'Tiger II' colonial bentgrass (Table 3). Heineck et al (2018) found 'Declaration' creeping bentgrass to have among the best seed germination rates for early spring laboratory test temperatures (mid-April) in their simulation test temperature of 7.0°C. Our field study indicated that 'Declaration' was a poor performer, requiring higher soil temperatures to achieve 90% grass cover during soil warming in early spring along with the lowest grass cover per day (4.5%/ d) and the lowest grass cover per°C (28.6%/°C) ( Table 2).…”

“…Alternatively, 'Memorial' creeping bentgrass in our field study performed well in terms of grass cover (Table 3), higher grass cover per day, and higher grass cover per°C (Table 2). In laboratory simulation tests Heineck et al (2018) concluded 'Memorial' should not be recommended for planting in early spring because of poor germination characteristics at 7.0°C. These results underscore the need to validate, in the field, simulation test temperatures conducted in the laboratory, as suggested by the work of Hardegree and Van Vactor (2000) because of the numerous biological, chemical, and physiological factors affecting establishment in the field (Egli and TeKrony, 1996;Hegarty, 1973;Weaich et al, 1996).…”

“…Growing degree day (GDD) models have been computed using soil or air temperatures collected daily. Base temperature varies with the crop with GDD for warm-season turfgrass establishment calculated using Tb close to 5°C (Frank et al, 1998;Patton et al, 2004;Shahba and Qian, 2008;Unruh et al, 1996), while for cool-season lawn grass species, values of Tb for seed germination ranged from 1.6 to 3.6°C (Larsen and Bibby, 2005), with bentgrass species exhibiting Tb closer to 10°C (Heineck et al, 2018;Trudgill et al, 2000).…”

“…Identifying bentgrass species and cultivars with the potential to establish under low soil temperatures would be beneficial toward achieving more mature stands earlier in the spring. Simulated field-temperature studies have been conducted in coolseason range grasses (Hardegree and Van Vactor, 1999), cool-season lawn grasses (Larsen and Bibby, 2005), and in cool-season turfgrass for golf use such as bentgrass species and cultivars (Heineck et al, 2018). However, these responses were not validated in the field.…”

Creeping bentgrass seed germination in growth chambers at optimal and suboptimal temperatures

“…Heineck et al. (2019) evaluated the germination of 21 creeping bentgrass cultivars under four day–night temperature regimes of 45:35, 55:35, 60:40, and 70:50 °F, representing historical temperature data for potential seeding dates in the upper Midwest and determined that germination rates increased as temperatures increased. The authors also found that temperatures below 45 °F were too low for creeping bentgrass seed germination.…”