Bradley Ridoutt1,2, Jing Huang3. 1. Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Agriculture and Food , Clayton South , Victoria 3169 , Australia. 2. University of the Free State , Department of Agricultural Economics , Bloemfontein 9300 , South Africa. 3. College of Life Science and Engineering , Southwest University of Science and Technology , Mianyang 621010 , China.