国家公益性行业农业科研专项No.201203045;国际植物营养研究所项目IPNI;陕西省教育厅专项科研计划项目No.12JK0653Supported by the Special Fund of National Non-profit Scientific Research Program for Agriculture No.201203045,the Program of International Plant Nutrition InstituteIPNI and the Scientific Research Special Program of Shannxi Provincial Ecucation DepartmentNo.12JK0653