Adaptation of Nordic forage crops to a changing climate Áslaug Helgadóttir, Agricultural University of Iceland, Árleyni 22, IS-112 Reykjavík, Iceland aslaug@lbhi.is In the Nordic environment the main limiting factors for forage crops are a short and cool growing season and various winter stresses such as frost, ice encasement, low temperature fungi, prolonged snow cover, water logging and low light intensity. The expected changes in climate at northern latitudes will result in a longer growing season, because of earlier spring and later autumn, and higher temperatures during the growing season, both of which may lead to increased biomass production potential. However, new types of stresses may offset the potential gain, such as increased disease pressure and insufficient hardening conditions during autumn to prepare the plants for altered winter conditions. As temperature and photoperiod both play a part in the acclimation process we need plants that are adapted to different combinations of climatic variables and at the same time possess higher biomass production potential. In this context it is necessary to consider factors such as growth cessation in autumn in relation to acclimation, deacclimation and reacclimation, carbohydrate dynamics during autumn and winter, and photosynthetic activity and respiration at low temperature and light intensity. Timothy has been the major grass species in the Nordic region north of 60°N but perennial ryegrass has played a role in the more maritime regions. With its high biomass yield and regrowth capacity, and superior feed quality ryegrass will undoubtedly become a promising option with prolonged growing season and milder winters. Similarly, forage legumes, that currently lack sufficient winter hardiness, will play an increasing role due to their N-fixing capacity. In adapting these species to new conditions in the north we will probably have to search for new variation in exotic material and introgress the most promising material into present cultivars. As grassland agriculture in the region is a low value enterprise it would be desirable to breed material with as wide adaptation as possible so material could be used across larger areas within specific agroclimatic zones rather than focus on narrow adaptation to certain geographic regions. Such an approach would require considerable pre-breeding efforts in line with the already initiated Nordic Public Private Partnership. Further, the use of grass-legume mixtures should be promoted, thus benefitting from the positive response of legumes to increased levels of temperature and CO2 in future climate. Transgressive overyielding has been observed in mixtures and they can better deal with climatic variability and stress. |
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