1. School of Advanced Agriculture and Bioengineering Yangtze Normal University Chongqing 408100 P. R. China
2. College of Food Science Southwest University Chongqing 400715 P. R. China
3. Chongqing Yudongnan Academy of Agricultural Sciences Chongqing 408000 P. R. China
4. South Subtropical Crops Research Institute Chinese Academy of Tropical Agricultural Sciences Guangdong 524091 P. R. China