Effects Of Microbial Fertilizer Application On The Growth,physiology,and Soil Environment Of Ginkgo Biloba Trunk-cutting Seedlings

Ginkgo biloba L.leaves and fruits contain medicinal components such as extracted flavonoids and lactones,which have a significant social demand and their quality affects their application.This study aimed to promote plant growth and increase leaf yield through the application of microbial fertilizer,in order to achieve green fertilization and effective fertilization of Ginkgo leaf forests,promoting the accumulation of total flavonoids in leaves.This study conducted a two-year fertilization experiment from 2021 to 2022,using a 3-year-old of Ginkgo biloba L.trunk-cutting seedlings as the research object.Eight treatments were set up,including CK（no fertilizer control）,T1 trunk-cutting seedlings（N:P₂O₅:K₂O=9:18:18）,T2trunk-cutting seedlings（N:P₂O₅:K₂O=9:27:27）,T3 trunk-cutting seedlings（N:P₂O₅:K₂O=9:18:18）+microbial inoculants,T4 trunk-cutting seedlings（N:P₂O₅:K₂O=9:27:27）+microbial inoculants,T5 trunk-cutting seedlings（microbial inoculants only）,T6 not trunk-cutting seedlings（N:P₂O₅:K₂O=18:18:18）,and T7 trunk-cutting seedlings（N:P₂O₅:K₂O=18:18:18）,Study the effects of combined application of formula fertilizer and microbial fertilizer on the growth traits,physiological characteristics,soil physicochemical properties,and soil microbial community content of G.biloba trunk-cutting seedlings.Through correlation,principal component analysis,membership function,regression analysis and interpretive structural modeling methods,select suitable fertilization models and cultivation techniques for G.biloba trunk-cutting seedlings.The results of two consecutive years of fertilization experiments indicate that:（1）The combined application of microbial fertilizer had different promoting effects on the number of new sprouts and single leaf yield of pruned Ginkgo biloba L.trunk-cutting seedlings.Among them,the total number of new sprouts in T4 and T5 fertilization treatments for two consecutive years were 0.86 and 0.92 times higher than the CK treatment,respectively;In two consecutive years of experiments,T2 and T4 fertilization treatments showed higher single plant leaf yield.Among them,after fertilization treatment in the first year,the single plant leaf yields of T2 and T4 were 0.67 times and 0.54 times higher than that of the CK treatment,respectively.At the same time,through the comprehensive evaluation of principal components and membership functions,it was found that the comprehensive performance of growth traits in T4fertilization treatment was better.（2）The combination application of microbial fertilizer had different effects on the chlorophyll photosynthetic products and secondary metabolites of pruned Ginkgo biloba L.trunk-cutting seedlings.Among them,in each month of the first year,plants treated with T1 and T3 fertilization showed higher chlorophyll photochemical efficiency（Fv/Fm）and actual photochemical efficiency（Fv’/Fm’）compared to other treatments,which had a positive impact on the photosynthesis of Ginkgo biloba L.trunk-cutting seedlings and helped to improve their growth and stress resistance.In each month of the first and second years,the total flavonoids（quercetin,isorhamnetin,and kaempferol）in the fertilization treatment increased to varying degrees,all higher than the CK treatment.In September of the first year,the total flavonoid content in the treatment group was 0.07-0.45 times higher than that in the control group under the application of microbial fertilizer,while in September of the second year,the total flavonoids content in the CK treatment was 0.10-0.39 times higher under each fertilization treatment.The principal component comprehensive evaluation showed that T2 treatment had better physiological characteristics,while the membership function comprehensive evaluation showed that T4 treatment had better physiological characteristics.（3）There were differences in the effects of microbial fertilizer application on soil physical properties.The experimental results showed that in september of the first year,CK treatment without fertilization had the highest compaction degree,smaller soil pores,and higher bulk density,while CK treatment had a lower total flavonoid content,which was not conducive to the accumulation of total flavonoids;Under T2 fertilization treatment,the soil moisture density was the highest and the number of leaves per plant was also the highest,indicating that in the first year of fertilization treatment,the yield of leaves per plant was the best.In September of the following year,T7 and CK treatment had the highest compaction,which means that the soil had a higher density,smaller pores,and higher bulk density,which was not conducive to the accumulation of flavonoids.After T4 fertilization treatment,the soil compaction was the lowest,indicating that the soil was relatively loose,resulting in the highest number of leaves per plant,which was beneficial for improving plant leaf yield.（4）The effect of microbial fertilizer combination on the microbial diversity of rhizosphere soil was also different.After two consecutive years of long-term fertilization,compared with CK without fertilization,the diversity of soil microorganisms and the number of taxonomic groups at all levels will decrease.However,the similarity between CK treatment without fertilization and those with fertilization was lower,and the proportion was also different.Among the top 10 bacterial phyla classifications,in the T4 treatment,other bacterial phyla Others accounted for the highest proportion at 18.2%,Gammaproteobacteria accounted for15.1%,and Vicinamibacteria accounted for 14.1%.The microbial community treated with T4can improve soil texture and make it more loose,which was conducive to the growth of more leaves per Ginkgo biloba plant and increase leaf yield.At the same time,it can also affect the accumulation of total flavonoid content,thereby improving the medicinal value of Ginkgo biloba.In summary,the combined application of microbial fertilizer has a promoting effect on the growth,photosynthesis,and secondary metabolites of pruned Ginkgo biloba.L forests,but its effects on soil physical properties,rhizosphere soil,and non rhizosphere soil vary.The T4treatment showed the best comprehensive effect.In continuous experiments for 2 years,the T4fertilization treatment could significantly increase the total number of new shoots and single leaf yield,furthermore,promote growth and increase the accumulation of flavonoids,with good physiological characteristics and growth traits.