1. Agricultural University of Cracow, Faculty of Agriculture and Economics, Department of Plant Physiology, Podluzna 3, 30–239 Kraków, Poland;
2. Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyñska 34, 60–479 Poznañ, Poland;
3. Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK