Impacts Of Biofertilizers And Metal Nanofertilizers On The Rhizosphere Microorganisms And Herbal Quality Of Salvia Miltiorrhiza

Salviae Miltiorrhizae Radix et Rhizoma(Danshen)is a famous Chinese medicine for promoting blood circulation and removing blood stasis,has extremely high medicinal and research value.However,there is lack of systematic scientific research as a guide on the application of types of fertilizers used in the cultivation of Salvia Miltiorrhiza.Bio fertilizers are widely used in agriculture due to having the ability to increase the yield of crops,improve the quality of the crop,improve soil fertility and help to reduce heavy metal accumulation in crop.In addition,metal oxide nanoparticles(MONPs)are also widely used in the cultivation of crops as a nanofertilizers.It is important to determine possible impacts(positive or negative)of bio fertilizers and MONPs on Salvia Miltiorrhiza.This study investigated the effects of four bio fertilizers(TTB,VZ,MI and GE)and three MONPs(CuO,Fe2O3 and ZnO)on the herbal quality of Salvia Miltiorrhiza.The above-and underground biomass,bioactive compounds synthesis,(heavy)metals uptake and soil physical and chemical indexes were evaluated based on pot and plot experiments.The behavior of soil microbial communities was also characterized.Results are as follows:(1)Pot and plot experiments simultaneously indicated that TTB and VZ have a positive impact on the growth,bioactive compounds accumulation and rhizosphere microecology of Salvia Miltiorrhiza.Compared to the control,the above-and underground biomass significantly increased by 16.27%-17.66%and 24.94%-71.17%,respectively(P<0.05);The content of total tanshinone significantly increased by 89.63-107.82%(P<0.05);TTB significantly increased the content of salvianolic acid B by 1.92%(P<0.05);Pb uptake significantly decreased by 37.58%-46.03%;the relative abundances of beneficial microorganisms in rhizosphere soil increased significantly,including heavy metal biosorption microbes(such as Bosea,Pedomicrobium,Achromobacter and Beauveria),plant growth promoting microbes(such as Bradyrhizobium,Penicillium)and microbes related to biodegradation of organic pollutants and biocontrol of plant disease(such as Paraphoma,Plectosphaerella,Clonostachys,Sorangium and Phlebiopsis).(2)MI and GE treatments significantly reduced Cd uptake by 5.84%-37.90%and increased the accumulation of total tanshinone by 9.90%-40.45%as compared to the control.The relative abundances of beneficial microorganisms with potential for bioremediation of heavy metals significantly increased in treated rhizosphere soils,such as Brevundimonas,Microbacterium,Cupriavidus and Aspergillus(P<0.05),especially Cupriavidus and Aspergillus have a strong tolerance to Cd.(3)The impacts of MONPs on Salvia Miltiorrhiza are closely associated with the types and concentrations ofNPs.Relative to the control,ZnO(100 mg/kg)and Fe2O3 NPs(100,700mg/kg)significantly increased the aboveground biomass,underground biomass and maximum root diameter by 20.76%-71.25%,53.95%-119.88%and 71.02%-119.88%(P<0.05),respectively;CuO NPs(100,700 mg/kg)had no significantly impact on the plant growth(P<0.05);CuO and ZnO NPs(100,700 mg/kg)significantly increased the Cu and Zn contents in roots(P<0.05);CuO(100 mg/kg)and ZnO NPs(100 mg/kg)significantly decreasd the Fe content in roots(P<0.05);Fe2O3 NPs had no significantly impact on the Cu,Fe and Zn contents in roots;Fe2O3 and ZnO NPs significantly increased the fungal diversity indexes by 13.13%-30.39%(P<0.05);the relative abundances of heavy metal resistant microbes and superoxide dismutase producer were significantly increased such as Sphingomonas,Flavisolibacter,Arenimonas,Thiobacillus,Methylobacillus and Aminobacter.This study indicated that bio fertilizers have a positive impact on the herbal quality of Salvia Miltiorrhiza,the rhizosphere micro-ecology and the soil fertility.The application of TTB,VZ,MI and GE significantly increased the accumulation of plant biomass and bioactive compounds in Salvia Miltiorrhiza and decreased the Pb and Cd content in roots,increasing the yield of herbs,improving the quality of medicinal materials,ensuring medicinal safety and efficacy Biofertilizers also have a positive impact on the rhizosphere micro-ecology,increasing the relative abundances of beneficial microorganisms which have the potential for plant growth promoting,organic pollutants biodegradation,plant disease biocontrol and heavy metal bioremediation.MONPs have a positive or negative impact on Salvia Miltiorrhiza in certain concentration ranges and types of MONPs,in terms of plant biomass,metal content and rhizosphere microbes.The application of MONPs in the cultivation of certain medicinal plant needs a systematical research.This study provided an insight of the application of bio fertilizers and MONPs in medicinal plants.