1. Institute of Plant Physiology, Karl‐Franzens University of Graz, Schubertstraße 51, A‐8010 Graz, Austria;
2. Present address: Seed Conservation Department, Royal Botanic Gardens Kew, Wakehurst Place, Ardingly RH17 6TN, UK
3. School of Botany and Zoology, University of Natal, Private Bag X01, Pietermaritzburg, Scottsville 3209, Republic of South Africa;
4. Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia;