Editors

(www.cimmyt.org), is a not-for-profi t research and training organizati on with partners in over 100 countries. The center works to sustainably increase the producti vity of maize and wheat systems and thus ensure global food security and reduce poverty. The center’s outputs and services include improved maize and wheat varieti es and cropping systems, the conservati on of maize and wheat geneti c resources, and capacity building. CIMMYT belongs to and is funded by the Consultati ve Group on Internati onal Agricultural Research (CGIAR) (www.cgiar.org) and also receives support from nati onal governments, foundati ons, development banks, and other public and private agencies. CIMMYT is parti cularly grateful for the generous, unrestricted funding that has kept the center strong and eff ecti ve over many years. © Internati onal Maize and Wheat Improvement Center (CIMMYT) 2011. All rights reserved. The designati ons employed in the presentati on of materials in this publicati on do not imply the expression of any opinion whatsoever on the part of CIMMYT or its contributory organizati ons concerning the legal status of any country, territory, city, or area, or of its authoriti es, or concerning the delimitati on o