Effects of Different Sowing Densities and Seed Volatile Limonene on the Seed Germination of Panax notoginseng

• Wenjing MA, 
• Shuang LIU, 
• Yixiang LIU, 
• Min YANG, 
• Xiahong HE, 
• Youyong ZHU, 
• Shusheng ZHU, 
• Huichuan HUANG