EVALUATION OF FREEZING TOLERANCE AND SUSCEPTIBILITY TO MICRODOCHIUM NIVALE OF VELVET BENTGRASS CULTIVARS IN CONTROLLED ENVIRONMENTS

摘要

Velvet bentgrass (Agrostis canina L.) ‘Avalon’,‘Greenwich’,‘Legendary’,‘Venus’,‘Vesper’,‘Villa’,and creeping bentgrass (A.stolonifera L.) ‘Penn A-4’,were tested for freezing tolerance and susceptibility to Microdochium nivale (Fries) Samuels and Hallett under different simulated winter covers (uncovered,snow,and ice) which lasted for 6 and 12 weeks.Cold hardening significantly improved freezing tolerance and tolerance to anoxia.The different hardening treatments affected freezing tolerance of the turf in the following order: unhardened < hardened at 2°C with light for 2 wk < hardened at 2°C with light for 2 wk with additional subzero hardening at -2°C for 2 wk in darkness < hardening in the field during fall.Differences in freezing tolerance between velvet bentgrass cultivars and creeping bentgrass ‘Penn A-4’ and among velvet bentgrass cultivars were generally not significant.The bentgrass resistance to M.nivale was enhanced by hardening and significantly affected by winter covers.Unhardened velvet bentgrass was more susceptible to microdochium patch than creeping bentgrass.Similar freezing tolerance in velvet bentgrass and creeping bentgrass was associated with similar levels of sucrose in crown tissue.The concentration of fructans in crowns of hardened creeping bentgrass was 50% higher than in crowns of hardened velvet bentgrass,but this did not result in higher freezing tolerance or higher resistance to M.nivale.