Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, Northwest Agricultural and Forestry University, affiliation not provided to SSRN, Shandong Agricultural University, Beijing Academy of Agriculture and Forestry Sciences and Northwest Agricultural and Forestry University