RESUMO
In order to investigate effects of Platycodon grandiflorum and pepper intercropping on root growth, yield and quality of P. grandiflorum, field experiments were conducted in the soils of continuously cultivated P. grandiflorum for three years. The cultivation model was designed as monoculture and intercropping. The monoculture of P. grandiflorum was denoted as CK and the intercrop association of P. grandiflorum/pepper was arranged as follow: in intercrops every two rows of pepper was planted between every three, four and five rows of P. grandiflorum, respectively, and denoted as JC₃₂, JC₄₂ and JC₅₂. Results showed that taproot length and diameter of P. grandiflorum in intercropping association of JC₃₂ was higher than those of P. grandiflorum in monoculture association. This fact suggested that P. grandiflorum intercropped with pepper facilitated its root growth. Compared with monoculture association, the number of lateral root in intercropping association was significantly decreased and the location of lateral root at taproot also altered. This fact suggested that P. grandiflorum intercropped with pepper enhanced appearance quality of P. grandiflorum root. Total root yield and taproot yield of P. grandiflorum in JC₄₂ and JC₅₂ intercropping associations were increased by 4.88%, 8.91% and 14.23%, 12.92%, respectively, compared with monoculture, while root rot incidence decreased significantly. Compared with JC₅₂ intercropping association, JC₄₂ intercropping association significantly increased total saponin and protein contents of P. grandiflorum, decreased root rot incidence, but did not affect taproot yield significantly. Considering root yield and quality, when P. grandiflorum planted in the soil having continuously cultivated P. grandiflorum for three years, the optimal cultivation model was every two rows of pepper was planted between four rows P. grandiflorum.