The genetic improvement of forage grasses and legumes to enhance adaptation of grasslands to climate change

Summary for policymakers. Grasslands cover about 70% of the world’s agricultural area. They have a crucial role in terms of food production and in the delivery of ecosystem services such as water supplies, biodiversity and carbon sequestration. The grasslands of the world face a range of challenges from climate change including the effects of elevated atmospheric carbon dioxide, increasing temperatures, changes in precipitation regime and higher concentrations of ground level ozone. These factors threaten productivity, species composition and quality, with potential impacts not only on livestock production but also on other aspects of the multifunctional role of grasslands. In a previous work we considered the contribution grasslands make to greenhouse gas emissions and the potential of genetic improvement of key grassland species to reduce these emissions and enhance carbon sequestration in grassland soils. In this paper we summarize the targets and approaches plant breeding programmes should adopt to enable grasslands to adapt to climate change whilst realizing their potential contributions to food security and reducing the environmental impact of livestock agriculture. We focus on the following major challenges: (i) Developing grassland crops with improved drought tolerance and enhanced water use efficiency. (ii) Improving tolerance of saline soils (iii) Tolerance of floods and related consequences of changes in rainfall patterns (iv) Maintaining nutrient use efficiency and forage quality In general the most advanced examples are from work carried out on the key species of temperate grasslands. State of the art genomic approaches are beginning to be deployed in these crops. However, there is an urgent need for increased public sector resources to be dedicated to the development of new varieties of grassland crops for the tropics and sub-tropics. Genetic improvement approaches could be complemented by research to explore the potential of introduced species and ecotypes and allied with modeling of climate change scenarios to facilitate breeding targeted to the needs of regions most affected.