1. Department of Botany, University of British Columbia, Vancouver, V6T 1Z4, Canada
2. Department of Citriculture, ARO, The Volcani Centre, Bet‐Dagan 50250, Israel
3. Soil and Water Sciences Division International Rice Research Institute, P.O.Box 933, Manila, Philippines
4. Plant Nutrition Laboratory, Royal Veterinary and Agriculture University, DK‐1871 Frederiksberg, Denmark
5. AgBiotech Centre, Cook College, Rutgers University, New Brunswick, NJ08903–0231, USA