1. School of Water, Energy and Environment; Cranfield University; Cranfield MK43 0AL UK
2. Department of Earth Science and Engineering; Imperial College London; London SW7 2AZ UK
3. Crop Production and Environment Division; Japan International Research Center for Agricultural Sciences; 1-1 Ohwashi, Tsukuba Ibaraki 305-8686 Japan
4. Crop and Environmental Sciences Division; International Rice Research Institute; DAPO BOX 7777 Metro Manila Philippines