Mycorrhizal colonisation in roots ofHolcus lanatus(Yorkshire Fog) in a permanent pasture under conditions of reduced precipitation

Abstract

The UK climate is projected to become warmer, with more frequent hotter, drier summers. Many governments and international organisations are concerned about how climate change will affect food production and security. Mycorrhizal fungi are an essential part of agricultural systems and yet little is known about how climate change will affect mycorrhizal fungi. We investigated the effect of reduced precipitation on levels of arbuscular mycorrhizal (AM) colonisation in the top 10 cm of soil in the grass Holcus lanatus L. (Yorkshire Fog) in a permanent pasture in South Gloucestershire, UK. Incident rainfall was reduced, by approximately 50%, using clear gutters supported on steel frames. Over three growing seasons we observed little difference in levels of AM colonisation and numbers of intra-root fungal structures between the roots of H. lanatus grown with reduced or full incident rainfall. Time of year when water stress occurred had a stronger effect on levels of colonisation than the absolute amount of precipitation received. In H. lanatus, growing in a permanent pasture, levels of AM colonisation were around 40%–50%, across a range of precipitation, from 18% above to 36% below the long-term average. The results highlight the complex relationships between mycorrhizal fungi, host plant, and abiotic stress.