Beijing Key Laboratory of Vegetable Germplasms Improvement Beijing Vegetable Research Center Beijing Academy of Agriculture and Forestry Sciences Beijing 100097 P.R.China;
Supervision Inspection and Test Center of Vegetable Seed Quality of Ministry of Agriculture and Rural Affairs Beijing 100097 P.R.China;
Beijing Key Laboratory of Seed Disease Testing and Control College of Plant Pathology China Agricultural University Beijing 100093 P.R.China;