State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Agriculture, South China Agricultural University, Guangzhou 510642, PR China; Scientific Observing and Experimental Station of Crop Cultivation in South China, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, PR China; Guangzhou Key Laboratory for Science and Technology of Fragrant Rice, Guangzhou 510642, PR China. Department of Agronomy, University of Agriculture, Faisalabad, Punjab 38040, Pakistan. Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan 430070, PR China. College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Agriculture, South China Agricultural University, Guangzhou 510642, PR China; Scientific Observing and Experimental Station of Crop Cultivation in South China, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, PR China; Guangzhou Key Laboratory for Science and Technology of Fragrant Rice, Guangzhou 510642, PR China. Electronic address: tangxr@scau.edu.cn.