Variation in Drought Tolerance of Perennial Ryegrass (Lolium perenne L.)

Global climate change is one of the biggest challenges for research in agricultural science. In Europe, expected temporary periods of reduced precipitation during the growing season will affect crop yields. Perennial ryegrass (Lolium perenne L.) is one of the most important forage grasses in Europe due to high yields and nutritional composition. Because perennial ryegrass has no distinct tolerance to drought, it is likely to be particularly affected by global climate change. Perennial ryegrass is found in many geographical regions across Europe, thus genetic variation for drought tolerance is likely. We have evaluated persistence under temporary drought conditions of 200 accessions, representing gene bank material from several countries with differing amounts of precipitation as well as breeding material. The evaluation was based on field trials at drought-prone locations. A contrasting drought response could be detected within the accessions and a representative subsample of 54 accessions could be identified for use in a two location rain-out shelter trial. Different methods for phenotyping recovery after drought stress were compared and traits were scored on a single plant basis in the semi-controlled environment rain-out shelter. A huge variation was found not only between, but also within accessions. It became obvious that the most important mechanism under Central European drought conditions is not maintenance of biomass production under severe drought stress but rather fast recovery after a limited period of water shortage. Single clones with contrasting recovery performance could be identified and will be used to investigate drought tolerance mechanisms and breed new varieties in future projects.