LI En-yao1,QIU Ya-qun1,PENG Pei-qin1,HOU Hong-bo1,LI Yu-yuan2,REN Ke-ai3(1.Environmental Science and Engineering Research Center,Central South University of Forestryand Technology,Changsha 410004,2.Key Laboratory of Subtropical Agro-ecology,Institute of SubtropicalAgriculture,Chinese Academy of Sciences,Changsha 410125,3.Xiangyin Agriculture Bureau,Xiangyin,Hunan 410500)