Adaptation of Norwegian perennial forage crops to ...

NJF Report, Vol. 6, No., 3, 2010

20-22 June, Hvanneyri, Iceland

Adaptation of Norwegian perennial forage crops to future climates L. Østrem1), M. Höglind2), Å. Karlsen3), P. Marum4), A.M. Tronsmo6), O.A. Rognli6) Norwegian Institute for Grassland and Environmental Research (Bioforsk), 1)Fureneset, N6967 Hellevik i Fjaler, 2)Særheim, Postvegen 213, N-4353 Klepp st., Torggården, N-8049 Bodø,

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Bodø, Kudalsveien,

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Graminor Ltd., Hommelstadvegen 60, N-2322 Ridabu,

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Norwegian University of Life Sciences, P.O.Box 5003, N-1432 Ås, all in Norway

Abstract The main aim for the project ”Understanding the genetic and physiological basis for adaptation of Norwegian perennial forage crops to future climates” is to generate plant material of red clover (Trifolium pratense L.) and lucerne (Medicago sativa) adapted to a variety of climatic conditions which might be used for selection of future cultivars. Mechanistic modelling of plant performance under climate change will be used to identify target traits for these cultivars, and during the project period of 2010-2013 main challenges for winter survival and persistence as well as for early growth in red clover will be elucidated.

Introduction Expected climate change will result in new growth conditions for forage production due to an extended (1-3 months) growth season combined with milder and more humid autumns and winters (Hansen-Bauer et al., 2009). In combination with the seasonal photoperiodic changes this raises a need for new ideotypes with a different set of physiological traits than the present cultivars (Semenov & Halford, 2009). ”Understanding the genetic and physiological basis for adaptation of Norwegian perennial forage crops to future climates” is a four-year project (2010-2013) investigating important traits for Norwegian forage crops including red clover (Trifolium pratense L.) and lucerne (Medicago sativa) in addition to grass species in view of future climate changes. The project is interdisciplinary involving mechanistic modelling of plant performance under climate change to identify target traits and germplasm, crossing and pre-breeding to increase genetic variation and resilience in the breeding populations, physiological and molecular genetic studies of cold acclimation in autumn and de-acclimation in spring including the effects of ice-encasement and water-logging, molecular markers and chlorophyll fluorescence for development of more efficient selection methods, and investigations of fungal disease resistance that are expected to be even more important in future due to changes in temperature, humidity and light conditions. New cultivars are required in order to utilize the potential for increased biomass production due to higher temperatures in the growth season and to survive a milder and more variable winter climate.

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Two forage legumes will be investigated; red clover and lucerne. Red clover is the main forage legume in Norwegian agriculture, being part of most marketed seed mixtures. The yield potential is, however, most often limited by insufficient persistence due to factors like lack of adaptation to climatic conditions (e.g. lack of hardening), unfavourable management systems (e.g. excess N-fertilization) and diseases. Biotic winter damages due to clover rot (Sclerotinia trifoliorum), a major disease deserving attention, will be assessed aiming at revealing variation in resistance between and within the populations. Current varieties depend on cold hardening to express maximum disease resistance. Increased amount of precipitation and higher temperatures during autumn may result in increased occurrence of Sclerotinia in new areas, partly due to lack of cold hardening, but also due to more favourable condition for the fungus. Abiotic stresses like water-logging during autumn and winter and frost and ice encasement will be studied especially in view of their effects on cold hardening and persistence. Genotypes with a stronger long day response in spring will be selected. The other forage legume, lucerne, is currently grown only in the Eastern part of Norway. Due to its high protein content and nutritive value it is of interest also in other regions, and potential adaptation of lucerne to wider geographic regions will be tested using field trials throughout Norway. For the modelling work, the LINGRA based models for grassland (Höglind et al, 2001; van Oijen et al. 2008) will be used to systematically study the effect of specific traits on winter survival and yield in grasses under different scenarios of climate change. The model simulates the development of snow and ice in the field, the development of frost and ice encasement tolerance, and the dynamics of biomass, tillers and water soluble carbohydrates as influenced by winter stress factors like frost, ice encasement, and low light conditions. The reliability of model results is quantified using Bayesian techniques. First, we will study the performance of existing cultivars under present conditions (to serve as a model-check) and under different scenarios of climate change. Secondly, we will run the models with a matrix of perturbed model parameters spanning the phenotypic variability of simple (physiological) traits with reasonably high heredity. We will use the most current climate scenarios provided by DNMI for the period 2040-2100 (Engen-Skaugen et al., 2008). The main focus will be on traits related to abiotic stress tolerance, i.e. against frost, ice, water logging. The effect of simultaneously changing several traits will also be investigated.

Materials and methods Locations Coastal locations: Særheim, South-West Norway (58°47’N, 5° 41’E, 80 m a.s.l.), Fureneset, Fjaler, West Norway (61° 34' N; 5° 21' E, 10 m a.s.l.), Tjøtta, North Norway (65°50’N,

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12°25’E, 15 m a.s.l.) and Vågønes, Bodø, North Norway (67°17’N, 14°27’E, 35 m a.s.l.); inland locations: Bjørke, Hamar, South Norway (60°48’N, 11°12’E, 200 m a.s.l.), Kvithamar, Stjørdal, Mid-Norway (63°26’N, 10° 52’E, 25 m a.s.l.) and Alta (69°58’N, 23°14’E, 20 m a.s.l.). Prebreeding in red clover and lucerne The populations of the forage legumes will be established in 2010 on 36 m2 plots. The two subsequent years the plots will be harvested with at least the current number of harvests of these species. In the third ley year vigorous plants will be selected for polycrossing. In red clover two genetically broad populations of diploid and tetraploid level will be sown on five locations (Bjørke, Særheim, Kvithamar, Vågønes and Alta). Additionally, two populations of each ploidy level specifically adapted for either southern or northern parts of Norway will be sown at two locations in each region. In lucerne, one population will be sown at all six locations (Bjørke, Særheim, Fureneset, Kvithamar, Tjøtta and Alta). Persistence in red clover For investigation of persistence in red clover, five populations of different ploidy and level of local adaptation will be sown at Fureneset (south) and Vågønes (north). Additionally, timothy will be sown for control purposes. The plant material will be established in 2010 in a field trial with four replications for registration of DM yield and plant development during the next two years. Identical clover material will be established in pots under both natural and controlled conditions for water logging experiments during the hardening period as effects on frost tolerance, regenerating ability (regrowth) and metabolic activity during autumn and winter. Resistance to clover rot will also be assessed in the same red clover populations. Surviving plants sampled from the field plots will be genotyped with genetic markers for studies of associations of markers with phenotypic characteristics of surviving plants. Long day (LD) response in red clover For genotypic selection of LD responses, four cultivars of red clover of each ploidy level will be established in the greenhouse in 2010 and selected for LD response in spring in the subsequent years.

Expected results Natural selection combined with management stress using genetically broad-based populations in diverse environments is a prebreeding tool that is expected to generate new germplasm for future development of cultivars with improved climatic adaptation. By testing

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broad populations of red clover and lucerne in all parts of the country (from 59°N to 70°N) we expect increased resilience to climate unpredictability. Identification of red clover germplasm with stronger response to LD conditions is expected to improve the generative growth and seed production of future red clover cultivars. The development of new cultivars that are persistent across different climatic scenarios also require identification of genotypes with resistance to clover rot that is expressed independently of cold hardening. Sampling and monitoring using genetic markers, and studies of associations of markers with compositional changes and phenotypic characteristics of surviving plants, in red clover especially focusing on disease resistance, is expected to provide marker information that can be implemented in breeding. The modeling study will provide further insight into the performance of different cultivars under a changing climate.

References Hansen-Bauer, I. (ed.) (2009). Klima i Norge 2100. Bakgrunnsmateriale til NOU Klimatilpassing. Foreløpig utgave juni 2009. http://www.regjeringen.no/upload/MD/Kampanje/klimatilpasning/Bilder/NOU/klimatilpas sing_ endelig_lavoppl.pdf. Höglind, M., Schapendonk, A.H.C.M. & van Oijen, M. (2001). Timothy growth in Scandinavia: combining quantitative information and simulation modelling. New Phytologist 151, 355-367. Van Oijen, M., Thorsen, S.M., Schapendonk, A.H.C.M., & Höglind, M. (2008). Process-based modelling of timothy survival in winter. In: Organizing committee of IGC/IRC Congress, eds. Multifunctional Grasslands in a changing world, Vol. 1. Guangzhou, Peoples Republic of China: Guangdong People's Publishing House, 893. Semenov, M.A. & Halford, N.G. (2009). Identifying target traits and molecular mechanisms for wheat breeding under a changing climate. Journal of Experimental Botany 60, 27912804.

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