Stereoscopic cultivation of Panax notoginseng: A new approach to overcome the continuous cropping obstacle

Stereoscopic cultivation (SC) of Panax notoginseng was a technique that plant P. notoginseng in the three-layer vertical placed seedbeds (with upper, middle, and lower layers) in a greenhouse. The cultivation environment of greenhouse and culture medium of seedbed are artificially prepared. The feasibility of using SC to solve the continuous cropping obstacle (CCO) of P. notoginseng was investigated in this study. The results showed that because the light and air temperature conditions of SC were inferior to those of field cultivation (FC), net photosynthetic efficiency was in the order of FC > upper > middle > lower layers. Soil microbial biomass values in the upper, middle, and lower layers were all significantly lower than those observed under FC. Soil urease, invertase, and neutral phosphatase activities increased gradually from the lower layer to the upper layer. Neutral phosphatase activity in each layer was significantly higher than that in the FC, and invertase activity in the upper and middle layers was significantly lower than that under FC, whereas urease and cellulase activities did not change significantly. Soil nitrogen and potassium contents were in the order of upper > middle layer > FC > lower layer, while the phosphorus content under SC was significantly higher than that in FC. The proportion of N and P in underground organs (rhizome, root tuber, and hair roots) of the upper layer increased, while it decreased in the middle and lower layers. Of the three layers, the proportion of K decreased significantly in the underground organs. The root biomass yield and saponin content in the same SC planting area was in the order of upper > middle > lower layer, which were all significantly lower than those of FC. However, total root biomass and saponin yield per unit floor area were 1.8 times that of FC. In conclusion, P. notoginseng grew normally under SC, and it was feasible to apply to solve the CCO. The yield and quality of P. notoginseng herbs can be further improved by perfecting the SC environment.