College of Horticulture, Agricultural University of Hebei, Baoding 071001, China;
College of Horticulture, Agricultural University of Hebei, Baoding 071001, China;
The Nursery in Beijing Thirteen Tombs Forestry Center, Beijing 102200,China;
The Nursery in Beijing Thirteen Tombs Forestry Center, Beijing 102200,China;
College of Horticulture, Agricultural University of Hebei, Baoding 071001, China;
The Nursery in Beijing Thirteen Tombs Forestry Center, Beijing 102200,China;