Effects of Panax notoginseng （Burk.） F. H. Chen-Bletilla striata rotation cropping under forest on alleviating continuous cropping obstacles and pathogen cross-infection analysis

【Objective】 This study aimed to investigate the effects of Panax notoginseng （Burk.） F. H. Chen-Bletilla striata-Panax notoginseng （Burk.） F. H. Chen rotation cropping under forest on alleviating continuous cropping obstacles of Panax notoginseng （Burk.） F. H. Chen and potential cross-infection risks between pathogens of the two plants， and to evaluate the effects of Panax notoginseng （Burk.） F. H. Chen root-zone soil on growth， quality， and disease of Bletilla striata for elucidating feasibility of Panax notoginseng （Burk.） F. H. Chen-Bletilla striata-Panax notoginseng （Burk.） F. H. Chen rotation cropping， thereby providing a theoretical basis for screening suitable rotation crops that could alleviate continuous cropping obstacles of Panax notoginseng （Burk.） F. H. Chen to achieve sustainable Panax notoginseng （Burk.） F. H. Chen cultivation. 【Method】 Bletilla striata was cultivated in continuous Panax notoginseng （Burk.） F. H. Chen cropping soil and natural soil under forest， and the differen-ces in growth parameters， quality， and disease of Bletilla striata planted in the two kinds of soil were measured to investigate the effects of continuous Panax notoginseng （Burk.） F. H. Chen cropping soil on Bletilla striata. Continuous Panax notoginseng （Burk.） F. H. Chen cropping soil was further utilized for rotation Bletilla striata cropping， and after that， Panax notoginseng （Burk.） F. H. Chen was replanted in that soil to determine seedling survival rate， dry weight， and saponin content of Panax notoginseng （Burk.） F. H. Chen to evaluate the effects of rotation Bletilla striata cropping on alleviating subsequent continuous cropping obstacles of Panax notoginseng （Burk.） F. H. Chen. Bletilla striata root and leaves were inoculated with pathogens of Panax notoginseng （Burk.） F. H. Chen root rot and leaves， and Panax notoginseng （Burk.） F. H. Chen root and leaves were inoculated with pathogens of Bletilla striata root rot and leaves respectively， to investigate the cross-infection between pathogens of Panax notoginseng （Burk.） F. H. Chen and Bletilla striata. Real-time fluorescence quantitative PCR was performed to analyze their common cross-infected pathogens. 【Result】 Compared with natural soil， continuous Panax notoginseng （Burk.） F. H. Chen cropping soil showed no significant negative effects on growth （plant height， biomass， and chlorophyll content）， quality （total phenol， polysaccharide， and Militarine content）， or disease （anthracnose， rust， and root rot） of Bletilla striata （P>0.05）. Replanting Panax notoginseng （Burk.） F. H. Chen after Panax notoginseng （Burk.） F. H. Chen-Bletilla striata rotation cropping could significantly increase root dry weight of Bletilla striata （P<0.05， the same below）， extremely significantly improve seedling survival rate of Bletilla striata （P<0.01， the same below） compared with plantation in continuous Panax notoginseng （Burk.） F. H. Chen cropping soil， and extremely significantly improve contents of total ginsenosides， Rg1， Rb1， R1， and Rd. Both Panax notoginseng （Burk.） F. H. Chen and Bletilla striata were susceptible to infection by root rot pathogens of Ilyonectria spp.； however， the contents of pathogens of Ilyonectria spp. were significantly decreased after rotation Bletilla striata cropping followed by continuous Panax notoginseng （Burk.） F. H. Chen cropping. 【Conclusion】 Continuous Panax notoginseng （Burk.） F. H. Chen cropping soil under forest exhibits no significant effects on growth， quality， and disease of Bletilla striata； Bletilla striata rotation cropping improves Panax notoginseng （Burk.） F. H. Chen seedling survival rate and quality， as well as reduces contents of pathogens of Ilyonectria spp. in soil. Panax notoginseng （Burk.） F. H. Chen-Bletilla striata-Panax notoginseng （Burk.） F. H. Chen rotation cropping is feasible under forest. Root rot pathogens cause cross-infection between Panax notoginseng （Burk.） F. H. Chen and Bletilla striata， therefore continuous monitoring of potential hazards in large-scale cultivation is recommended.