1. Department of Ornamental Horticulture, ARO, The Volcani Center, Bet Dagan, Israel;
2. Department of Horticulture, Cornell University, Ithaca NY, USA;
3. Laboratory of Biophysics and Wageningen NMR Centre, Wageningen University, Wageningen, The Netherlands;
4. Department of Chemical Services, MR Center, Weizmann Institute of Science, Rehovot, Israel