title: [A study on the rotation of crops among Panax quinquefolium, Perilla frutescens and Coix lacryma-jobi].
abstract: OBJECTIVE
  To provide evidence for establishing an efficient method of growing Panax quinquefolium by rotation of crops.
  
  
  METHODS
  Four-year old P. quinquefolium was cultivated in water and soil cultures. Biological assays were conducted with the aqueous extracts of P. quinquefolius, Fructus Perillae and roots of Coix lacryma-jobi. P. quinquefolium was cultivated in the soil where purple Perilla frutesens and C. lacryma-jobi were grown previously. The effects of rotation were determined.
  
  
  RESULTS
  The stems, leaves and fibrous roots of Panax quinquefolium contained allelopathic substances. When the concentration of the allelopathic substances exceeded 1g per kg soil, P. quinquefolius could not grow. On the other hand, when the concentration of allelopathic substances fell below 0.2 g per kg soil, the rate of seedling growth was decreased by 25%. When P. quinquefolius was cultivated in the soil in which purple Perilla frutesens had previously grown, or in the soil supplemented with Fructus Perillae, the rates of seedling growth and the yield were raised by 26.8% and 11.5% tively, in comparison with the controls.
  
  
  CONCLUSIONS
  Rotation of Panax quinquefolium and Perilla frutesens was shown to be a good way for the cultivation of the former. During the growing process, application of Fructus Perillae to the soil could further enhance the growth and of Panax quinquefolium.
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100094, China. zhaoyangjing@hotmail.com
authors.forename: Yang-Jing
authors.initials: YJ
authors.lastname: Zhao
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Jun-Shan
authors.initials: JS
authors.lastname: Yang
authors.forename: Dong
authors.initials: D
authors.lastname: Liu
mesh_terms: D000383:Agriculture / Q000379:methods*; D031742:Coix / Q000254:growth & development*; D018525:Germination / Q000187:drug effects*; D005894:Panax / Q000737:chemistry / Q000254:growth & development*; D031343:Perilla / Q000254:growth & development*; D010936:Plant Extracts / Q000302:isolation & purification / Q000506:poisoning; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry / Q000254:growth & development
chemical_list: D010936:Plant Extracts