| The continuous cropping obstacle caused by root-knot disease is still a major challenge for the growth of Panax notoginseng.The preliminary study of the research group found that the cruciferous crop Eutrema yunnanense has good suitability in the continuous cropping soil of P.notoginseng.Based on this,this study took the interaction between E.yunnanense and P.notoginseng as the starting point,and discussed the feasibility of E.yunnanense and its metabolites to improve the continuous cropping soil of P.notoginseng.The results are as follows:1.It is feasible to rotate Eutrema yunnanense after harvesting P.notoginseng under forest: After harvesting the 3-year-old P.notoginseng under the forest(the incidence of root rot in that year was 65%),the seedlings of E.yunnanense were transplanted according to the " Pin " shape on the original planting soil moisture surface.The row spacing was30,40 and 50 cm,respectively,and the plant spacing was 35 cm to 40 cm.The transplanting survival rate of six months was 95%.Through continuous 17 months of field observation,the results showed that the seedling survival rate remained 90%,and the growth was good.During the study period,one technical standard and one patent application for rotation planting of P.notoginseng and E.yunnanense were formulated.2.Effects of Rhizosphere Soil of E.yunnanense under Forest and allyl isothiocyanate(AITC)on Emergence of P.notoginseng: After planting for 15 months,the rhizosphere soil of E.yunnanense was directly planted in pots to sow the seeds of P.notoginseng.The emergence rate of P.notoginseng was 25% in three months,which was higher than that of continuous cropping soil(18%).The emergence rate of continuous cropping soil treated with AITC was 85.7% in 1 year and 86.1% in 2 years,which was higher than that of CK(control)74% in 1 year and 85% in 2 years.It shows that AITC treatment of soil has an effect on the emergence rate of P.notoginseng.It was proved that AITC secreted by the root of E.yunnanense(AITC)could improve the soil physical and chemical properties and soil permeability of understory soil and continuous cropping soil of P.notoginseng,and had an effect on soil microbial community structure,which was helpful to overcome the continuous cropping obstacle of P.notoginseng to a certain extent.3.Study on the prevention and control effect of allyl isothiocyanate(AITC)on P.notoginseng root-knot nematode disease: The number of root-knot nematodes per 100 grams of soil treated with allyl isothiocyanate(AITC)was 3.33,which was similar to that of steam treatment(3.16)and avermectin treatment(3.33),and significantly lower than that of CK(23).The investigation of the disease index of root-knot nematode in 1 year and 2years showed that the disease index of root-knot nematode in AITC treatment was significantly lower than that in CK treatment,and the disease index of root-knot nematode decreased gradually with the increase of AITC concentration.4.The effect of allyl isothiocyanate on the continuous cropping soil of P.notoginseng:The results showed that there was no significant difference in soil p H and available phosphorus content between continuous cropping soil and continuous cropping soil(CC),and the effect was not significant.The contents of organic matter,total nitrogen and available potassium were higher than those of continuous cropping soil,and the effect was significant.The effect of allyl isothiocyanate on the microbial community structure of continuous cropping soil: The effect of AITC treatment on soil microorganisms was obvious.The soil treated with AITC fumigation was compared with the test under the forest.The results showed that there was little difference between the two groups at the phylum level,and the difference was obvious at the order and genus level.The number of OTUs in the soil microbial community treated with AITC fumigation decreased,and the ACE index and Chao1 index in the alpha diversity of bacterial community were significantly lower than those of the control treatment.There is no significant difference between Simpson index and Shannon index.In summary,through the emergence rate and survival rate of E.yunnanense,it is proved that the rotation of E.yunnanense under the forest is feasible.The allyl isothiocyanate had a good control effect on root-knot nematodes in continuous cropping soil under forest.The secondary metabolites of allyl isothiocyanate could change the soil microbial community structure and soil physical and chemical properties of P.notoginseng continuous cropping soil to a certain extent,which was beneficial to P.notoginseng to improve the emergence rate and survival rate of P.notoginseng and reduce the probability of P.notoginseng root-knot nematode disease.In order to explore and promote the new forest medicine-forest vegetable compound planting mode,it provides a reference for improving the utilization rate of understory land,improving the quality of understory economic crops,overcoming the obstacles of continuous cropping of understory medicinal materials and disease control,and has important reference value for the planting and promotion of understory economic crops. |
