1. 1Department of Bioscience and Biotechnology, University of Strathclyde, 204 George Street, Glasgow G1 1XW
2. 2Institute of Arable Crops Research–Rothamsted, Harpenden, Herts, AL5 2JQ
3. 3Department of Statistics and Modeling Science, University of Strathclyde, 26 Richmond Street, Glasgow G1 1XH, UK