中国博士后基金No.2014M550374;宁夏回族自治区科技支撑计划项目No.2013Zys149;宁夏农林科学院自主研发项目No.nkyg-13-11Supported by the Chinese Postdoctoral Science Foundation No.2014M550374,the Ningxia Science-technology Support Plan ProjectsNo.2013Zys149 and the Indigenous Programs from Ningxia Academy of Agricultural and Forestry Sciences No.nkyg-13-11