1. Sabanci Univ., Faculty of Engineering & Natural Sciences, 34956 Istanbul, Turkey.
2. Corresponding author. Phone: +90 (216) 4839524. Fax: +90 (216) 4839550. E-mail: cakmak@sabanciuniv.edu
3. HarvestPlus, c/o CIAT, A.A. 6713, Cali, Colombia.
4. HarvestPlus, c/o IFPRI, 2033 K St., NW, Washington, DC 20006.