| Rehmannia glutinosa Libosch is a perennial herbaceous plant of the genus Diosgenaceae.Its me-dicinal value has a long history in China.It is mainly used as root medicine.It has the functions of clearing heat and nourishing blood,nourishing yin and promoting body fluids.It is an important traditional Chinese medicine.However,there are serious continuous cropping obstacles that affect the growth and develop-ment of digitalis.The causes of continuous cropping obstacles include the autotoxicity of plants,changes in soil properties,beneficial microorganisms,reduction of harmful microorganisms,increased diseases and insect pests,and soil element balance and damage to nutritional imbalances.It is unclear exactly what kind of factors cause severe continuous cropping obstacles to digitalis directly.In this paper,we mainly explore the effects of pests and trace elements on continuous cropping of Rehmannia glutinosa Libosch by control-ling the occurrence of pests and trace elements through field experiments.At the same time,different types of microbial preparations are appropriately applied in continuous cropping Rehmannia glutinosa Libosch to increase the diversity of beneficial microorganisms in the soil.To reduce the occurrence of diseases and insect pests,the characteristics of beneficial microorganisms in microbial inoculants are used to achieve the purpose of degrading phenolic acids,reducing harmful substances in the soil,and increasing nutrient components,so as to achieve the effect of reducing the obstacles of Rehmannia glutinosa Libosch.By measuring the growth index,protective enzyme activity and accumulation of MDA,the con-tent of medicinal components,the effects of metabolites cultivated by the extract of rhizoma glutinosa and microorganisms on the seeds of Rehmannia glutinosa Libosch in different growth stages of different treat-ments,different microorganisms were studied.What the effect of adding bactericides on continuous crop-ping Rehmannia glutinosa Libosch.Experimental results show that:（1）The effects of plant diseases and insect pests and trace elements on continuous cropping of Rehmannia glutinosa Libosch,there is no significant difference in the indexes of the above-ground part of the stubble and replanted plants throughout the growth period of Rehmannia glutinosa Libosch（P<0.05）.There was no significant difference in growth trends after 60 days of emergence in the fast-growing period.The quality of the underground part of continuous cropping Rehmannia glutinosa Libosch is lower than that of orthopaedic Rehmannia glutinosa Libosch,and it is significantly different from that of orthopaedic Rehmannia glutinosa Libosch.There is no significant difference between the treatment of pests and trace elements and heavy stubble,and the root weight is reduced,the content of medicinal ingredients is reduced,there is no significant difference between the number and the value of the drying rate.（2）Looking at the differences between the above-ground and underground parts of the whole continuous cropping Rehmannia glutinosa Libosch,it can be found that the effects of each treatment on the continuous cropping Rehmannia glutinosa Libosch are not completely synchronized,but the proper addi-tion of microbial agents has a certain effect on the continuous cropping Rehmannia glutinosa Libosch.With the addition of microbiocides,the fresh weight of the continuous cropping Rehmannia glutinosa Libosch underground tends to increase.Among them,Treatment 2 has the largest impact on it compared with other treatments,and Treatment 5 has a greater impact on the weight of individual roots,but the over-all roots.The number decreases.The addition of microbial inoculants can affect the chlorophyll content to different degrees,among which treatment 2 and treatment 3 have a greater effect,and treatment 4 and treatment 5 are the next.（3）Superoxide dismutase（SOD）and catalase（CAT）in the roots and leaves of continuous crop-ping Rehmannia glutinosa plant showed the same trend of rising first and then decreasing.Rehmannia glu-tinosa Libosch had the lowest SOD activity in leaves and roots during the 30-day period,and then gradu-ally increased.SOD activity in all treatments decreased after reaching the maximum value in the 90-day period.When the SOD activity of the roots reaches the highest,the order from highest to lowest is:treat-ment 4>treatment 2>treatment 5>treatment 3>treatment 1,and the SOD activity of the treatment 4 roots is up to 413.83 Ug-1.min-1 in the 90-day period;The CAT activity of treatment 2,treatment 3,treatment 4,and treatment 5 was higher than that of treatment 1 at each growth stage,and treatment 2,treatment 3,and treatment 5 had the greatest increase in CAT activity at the seedling stage compared to treatment 1 in the leaves of Rehmannia glutinosa Libosch,Which were 2.08 times,2.08 times,and 1.6 times of treatment 1,respectively;Treatment 4 had the greatest increase in the CAT activity of leaves of Rehmannia glutinosa Libosch at a period of about 90 days,which was 2.06 times that of treatment 1.At about 30 days after ger-mination,treatment 2,treatment 3,and treatment 5 had the greatest increase in CAT activity compared to treatment 1 and that of foxglove roots increased by 15.38%,38.46%,and 38.46%.The malondialdehyde content（MDA）of each treatment showed a consistent trend of increasing first,then decreasing,and then increasing during the whole growth period of Rehmannia glutinosa Libosch leaves,there was a certain accumulation of MDA in Rehmannia glutinosa Libosch leaves during the period of 30 days after emergence.The accumulation amount increased,and the MDA accumulation amount of continuous cropped Rehmannia glutinosa Libosch roots applied in treatment 1 and treatment 3 showed an increasing trend throughout the growth period,while the accumulation amount of root MDA in treatment 2,treatment 4 and treatment 5 increased first and then decreased.Different treatments showed lower levels at the seedling stage of 30 days after germination.Treatment 1,Treatment 3,and Treatment 4 reached higher levels at around 120 days of germination,while Treatment 2 and Treatment 5 reached lower levels at 60days of germination.（4）The effects of different treatments on the content of catalpol in the roots of continuous crop-ping Rehmannia glutinosa Libosch were as follows:the content of catalpol in the root of one root was the lowest,the content of verbascoside in the root was the lowest,the content of verbascoside in the two roots was the highest,and 4 The content of glycosides from rhizomes is the highest.Among them,the effect of Treatment 2 on the content of Verbascum in the roots of Rehmannia glutinosa Libosch was increased by54.19%than that of Treatment 1,and the largest increase compared with other treatments,which reached a significant difference.Treatment 3,Treatment 4,and Treatment 5 were respectively 22.22%,31.95%,and11.87%higher than Treatment 1.Treatment 4 had the largest effect on catalpol content in the roots of Rehmannia glutinosa Libosch,reaching 18.67 mg/g,an increase of 42.32%compared with 13.12 mg/g in Treatment 1,followed by Treatment 3,with a content of 17.09 mg/g.The content of catalpol in the roots of Rehmannia glutinosa Libosch was 16.06 mg/g and 13.66 mg/g,which increased by 22.411%and 4.09%.（5）Analysis of differential metabolites in different culture media,a total of 260 metabolites were detected.Compared with S1,S4 has 148 substances changed,and the number of reduced substances is 83,which is an increase of 65;S4 and S2 have 185 substances changed,which has decreased by 103 and in-creased by 82;S1 and S2 By comparison,195 substances changed,reducing 96 species and increasing 99species.S1 is compared with S4,while vanillic acid is 0.25 times that of S4,4-hydroxybenzaldehyde is0.06 times that of S4,and protocatechuic acid is 0.36 times that of S4;compared with S2,cinnamic acid is1.09 times that of S4,Protocatechuic acid is 17.16 times that of S4,vanillic acid is 0.01 times that of S4,benzoic acid is 0.04 times that of S4,and p-hydroxybenzoic acid is 0.01 times that of S4.（6）The effect of different media on the growth of Rehmannia glutinosa Libosch seeds,the root lengths of S1 and S2 were 8.4 times and 8.1 times that of S5,S3 is 2.44 times larger than S5 compared to S5.The effect of different culture mediums on the root length of Rehmannia glutinosa Libosch was larger than that of CK without extract,and the root length of CK was the largest,reaching a significant difference.The effects of S1 and S2 on stem length were increased by 22.95%and 50.13%,compared with S5,reach-ing significant levels,and the differences were significant compared with CK.The expression of Ca2+sensor in plant signal transduction,the transcription level of Ca ML in-creased to varying degrees,especially in the Rehmannia glutinosa Libosch seedlings treated with Bacillus amyloliquefaciens,the expression level was 30.07±2.69,which reached the highest,which was S2,S32.08 times and 2.01 times,the expression level of Ca M was significantly higher after co-cultivation of dif-ferent kinds of microorganisms than only the extract,and the expression level of co-culture treatment con-taining Bacillus amyloliquefaciens increased the most.In the expression level of Ca BL,the expression level of co-cultivation treatment containing Bacillus amyloliquefaciens and Bacillus subtilis was signifi-cantly higher than that of Rehmannia glutinosa Libosch seedlings treated with the extract alone,but the gene expression level of mixed microorganisms was significantly reduced.It was 0.97 times the expression of Rehmannia glutinosa Libosch seedlings treated with the extract.From the above conclusions,it can be concluded that the effects of diseases and insect pests and trace elements on continuous cropping of Rehmannia glutinosa Libosch,and there is no significant differ-ence in the indexes of the above-ground part of the continuous crop and the replanted crop.Decreased,and reached a significant difference with orthodox stubble,there was no significant difference between pests and microelements treatment and heavy stubble;compared with ordinary fertilizers,the addition of micro-bial inoculants to the continuous cropped foxglove biomass index has Increasing to different degrees can increase the root weight,the content of medicinal components,and the activity of the protective enzyme system of Rehmannia glutinosa;after co-fermentation and cultivationing with microorganisms and extracts of Rehmannia glutinosa,it can promote the growth of Rehmannia glutinosa Libosch seeds to a certain ex-tent,which can reduce the content of vanillic acid,p-hydroxybenzoic acid and protocatechuic acid. |
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