Sustainable primary production in a changing climate – effects to barley and oilseed rape from the future climate

Rikke Bagger Jørgensen¹, and Michael Lyngkjær² on behalf of this network

¹DTU, KT, Frederiksborgvej 399, P.O. Box 49, DK-4000 Roskilde, *rijq@kt.dtu.dk.

² Department of Plant and Environmental Sciences, Thorvaldsensvej 40, DK-1871 Frederiksberg C, mlyn@life.ku.dk  

With the present increase in the emission of greenhouse gasses, the [CO₂] will double to app. 700 ppm and the average global temperature will increase 4-5 °C by year 2075 (IPCC, 2013). For this changed environment new crop cultivars and disease control strategies are demanded.

We analyzed the effects in barley and oilseed rape from the future climate change.

In a climate phytotron (RERAF, DTU-Risø) future climate scenarios were applied to 138 accessions of barley and 32 accessions of oilseed rape. Production parameters were recorded in the different climate scenarios that represented elevation of single abiotic factors - [CO₂], [O₃] and temperature - and combinations of the abiotic factors. In a separate study it was examined, how the climate scenarios are affecting resistance to the fungal diseases spot blotch and powdery mildew. Production parameters and abundance of diseases were also evaluated under field conditions in a Free Air Carbon Enrichment facility.

Both for barley and oilseed rape the seed yield was significantly reduced in treatments with +5 ⁰C above ambient. When the [CO₂] was increased together with the temperature the yield deficit was reduced, but yield was still lower than in the ambient treatment (barley -30 %, oilseed rape -10 %). Large differences among accessions were recorded. Based on their environmental stability (S_i² and W_i²) some of the accessions could be identified as environmentally resilient, why they may serve in the breeding of cultivars for tolerance to future environmental variation. In an association mapping of the barley accessions, 118 SNP markers were found to link to production parameters recorded in the 5 different environmental treatments. When growing under elevated temperature or [O₃], infection by the biotrophic powdery mildew fungus decreased, whereas disease symptoms and growth of the toxin secreting hemibiotrophic spot blotch fungus increased compared to ambient conditions, implying that climate induced changes in disease severity could be linked to the trophic lifestyle of the pathogens. Combination of the climatic factors affected the diseases in an unpredictable non-additive manner, emphasizing the importance of conducting multifactorial experiments, when evaluating the potential effects of climate change. Enrich CO₂ atmosphere in the field increased biomass and yield and decreased severity of powdery mildew supporting the phytotron results.