Submitted to: Acta Agriculturae Scandinavica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/11/2005
Publication Date: 12/4/2006
Citation: Hofgaard, I.S., Wanner, L.A., Tronsmo, A.M. 2006. The effect of age and cold hardening on resistance to pink snow mould (microdochium nivale) in perennial ryegrass (lolium perenne l.) Acta Agriculturae Scandinavica, Section B - Plant Soil Science, Volume 56, (Number 4): 315 – 323. Interpretive Summary: Farmers in northern latitudes need crops with good winter survival characteristics, and need to know how to maximize the overwintering potential of crop plants they grow. Many grass and cereal species are capable of acclimating in fall in response to colder temperatures and shorter days to better withstand winter snow, ice and low temperature diseases, such as snow molds that attack and kill plants during winter while they are covered with snow. Plant age and the duration of cold hardening are two inter-related factors that are important in winter survival of grasses. In this study, we report that plant age alone, and not the duration of cold acclimation, is the critical factor in determining resistance to pink snow mold damage in perennial rye grass. Better understanding of the relationship of plant age (time of planting in the fall) and winter hardiness enables farmers to choose fall sowing times to reduce damage and loss in overwintering perennial rye grass.
Technical Abstract: The effect of plant age and cold hardening on resistance to pink snow mould caused by Microdochium nivale was studied in perennial ryegrass. Resistance to M. nivale was estimated as relative regrowth after inoculation and incubation under artificial snow cover at 2ºC. Resistance increased with increasing plant age. Cold hardened and unhardened plants of the same age displayed identical resistance. Preliminary studies indicate that expression of genes coding for the PR-proteins chitinase and PR-1a increased during incubation of inoculated perennial ryegrass, but no clear difference in expression of these genes was found between plants of different ages, or in hardened versus unhardened plants.