Influence of Applied Nitrogen and Clipping Treatments on Winter Survival of Perennial Cool-Season Grasses
1974
Jung, G. A. | Kocher, R. E.
A study to determine the extent to which winter injury of cool-season grasses was related to genetic variation in cold tolerance, nitrogen fertilization, or previous spring and summer clipping treatments was completed at Rock Springs, Pennsylvania. Visual estimates of the percentage of winter injury sustained during the winter of 1971–72 were made in mid-May. The grasses received 0, 60, 120, or 240 kg N/ha in spring and summer of 1971 and spring 1972. Half the plots at each rate of N were clipped at vegetative growth stages in spring, and in early June, late July, and early October. The other half were clipped after head emergence in spring, and in late August and early October. Average winter injury ranged from less than 1% for reed canary-grass (Phalaris arundinacea L.) to 83% for two perennial ryegrass (Lolium perenne. L.) cultivars. Kentucky blue-grass (Poa patensis L.) and smooth bromegrass (Bromus inermis Leyss.) were injured slightly (2 to 8%) more than reed canarygrass, and timothy (Phleum pratense L.) and redtop (Agrostis alba L.) sustained even more winter injury (12 to 18%). Average winter injury ranged from 14 to 57% for orchardgrass (Dactylis glomerata L.), 20 to 48% for tall fescue (Festuca arundinacea Schreb.) and 33 to 83% for perennial ryegrass. Nitrogen fertilization decreased winter survival of orchardgrass, tall fescue, and perennial ryegrass to a greater extent than it did other species. Kentucky bluegrass, smooth bromegrass, and reed canarygrass were not severely injured by either clip ping regime. One or more cultivars of orchardgrass, timothy, tall fescue, perennial ryegrass, and redtop sustained winter injury when clipped at immature growth stages but were not injured when clipped at mature growth stages. Differential injury associated with the clipping regimes increased as rate of N increased. The large differences in winter injury among cultivars of orchardgrass, tall fescue, and perennial ryegrass suggest that tolerances to environmental stresses ought to be more thoroughly tested if we are to use new cultivars most effectively.
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