Effects Of Applying Raw Garlic Stalk, AMF And Growing Overwintering Leafy Vegetables On Continuous Cropping Eggplant Under Plastic Tunnel Cultivation

Eggplant(Solanum melongena L.)is one of the most popular vegetable of this region,and China is currently occupied the largest producer of eggplant.However,the continuous cropping with eggplant terribly threatened the regional eco-sustainability by persuading replant problem under continuous-cropping condition.Long-term continuous cropping spans induced the continuous cropping stress usually manifested in plant growth inhibition and disruption of soil productivity,thus severely hindering the egg-plant industry in China.Raw Garlic stalk(RGS)is an important biological resource and can be used as soil amendment for protected cultivation of eggplant to improve plant growth and soil sustainability.Arbuscular mycorrhizal fungi(AMF)are most important microorganism and it can make symbiosis most of land plants.Due to the high value for agricultural ecosystem functioning and sustainability,AMF have attained the much more attention for several decades as biological substitutes to chemicals.Therefore,application of AMF with allelopathic crop residue i.e.RGS is very interesting,because it was first study of using AMF with RGS to evaluate their effect on plant growth and soil microbial diversity.Moreover,inclusion of winter leafy vegetable cropping in monocrpping soil was also studied first time to evaluate their effect on plant growth and soil microbial diversity.1.Soil Amendment with Raw Garlic Stalk:a Novel Strategy to Improve Growth,Anti-oxidative Defense System and Soil Microbiome in Monocropped EggplantGarlic(Allium Sativum L.)is a vegetable with known medicinal value.It is not only rich in nutrients,but also has the ability to combat with different microbial infections.The incorporation of plant residues into soil can be considered a keystone sustainability factor in improving soil structure function.However,the effects of plant residue addition on the soil microbial communities involved in biochemical cycles and abiotic stress phenomena are poorly understood.The experiments were conducted in pots using soil amendments of RGS in different ratios CK(without amendment),1%(1 g of RGS into 100 g of soil),3%(3 g of RGS into 100 g of soil),and 5%(5 g of RGS into 100 g of soil)and repeated in two consecutive years(2016 and 2017).The RGS amendment significantly increased soil electrical conductivity(EC),N,P,K,and enzyme activity.The soil p H significantly decreased with RGS application.High-throughput Illumina Mi Seq sequencing revealed significant alterations in bacterial community structures in response to RGS application.Among the 23 major taxa detected,Anaerolineaceae,Acidobacteria,and Cyanobacteria exhibited an increased abundance level.RGS2 increased some bacteria reported to be beneficial including Acidobacteria,Bacillus,and Planctomyces(by 42%,64%,and 1%respectively).Furthermore,internal transcribed spacer(ITS)fungal regions revealed significant diversity among the different treatments,with taxa such as Chaetomium(56.2%),Acremonium(4.3%),Fusarium(4%),Aspergillus(3.4%),Sordariomycetes(3%),and Plectosphaerellaceae(2%)showing much abundance.Interestingly,Coprinellus(14%)was observed only in RGS-amended soil.RGS treatments effectively altered soil fungal community structures and reduced certain known pathogenic fungal genera,i.e.,Fusarium and Acremonium.The results of the present study suggest that RGS amendment potentially affects the microbial community structures that probably affect the physiological and morphological attributes of eggplant under a plastic greenhouse vegetable cultivation system(PGVC)in monoculture.A dose-dependent response of RGS amendment was also observed in the growth and physiology of the eggplant.1%and 3%significantly enhanced the plant height,root/shoot weight,stem diameter,leaf area,root length,root activity,pigment contents(chlorophyll a,chlorophyll b,and total chlorophyll),and photosynthetic parameters,but reduced intracellular CO₂(Ci)and enhanced fruit yield as compared with the respective controls.Consistently,RGS also enhanced activities of antioxidative enzymes of eggplant reported as a defense against stress indicators.RGS in its higher ratios(RGS3),however,caused a reduction in all of the growth and physiological parameters and increased stress indicators such as hydrogen peroxide(H₂O₂)and malondialdehyde(MDA).Overall,RGS2 was found to be the most efficient for regulation of plant defense systems,reducing H₂O₂ and MDA and enhancing superoxide dismutase(SOD),peroxidase(POD),and phenylalanine ammonialyase(PAL)activity.It can be concluded that the appropriate ratio of 3%could efficiently promote plant growth and regulate the reactive oxygen-based plant defense system.2.Co-Application of Raw Garlic Stalk and AMF on Growth and Microbial Diversity of Replanted EggplantSoil-related obstacles resulting from continuous monoculture have limited the sustainable development of the eggplant industry in China.The application of organic amendments with arbuscular mycorrhizal fungi(AMF)is an economically viable and environmentally comprehensive method to develop sustainable agriculture.The aim of this study was to assess whether raw garlic stalk(RGS)amendment alone or combined with AMF application can be used to improve the growth and microbial diversity of monocropping soil of eggplant.The treatments included control CK(without amendment and AMF),RGS 3%,AMF and RGS 3%+AMF(ARGS).The results showed that the application of RGS and AMF alone or in combination improved plant height,stem diameter and root activity with all treatments.However,the highest plant height,stem diameter,photosynthesis was recorded for ARGS among all treatments.High-throughput Illumina Mi Seq sequencing revealed significant changes in the bacterial community structures in response to RGS and AMF application.Among 12 phyla detected in soil Protobacteria 28%,Chloroflexi 13%,Acidobacteria 11%and Actinobacteria 10%are most dominant phyla.It increases some beneficial phyla like Protobacteria,Bacillus and Firmicutes.Furthermore,ITS fungal regions revealed significant diversity among the different treatments with genus level most dominant genera were Chaetomium(42%),Coprinellus(8%),Fusarium(5%),and Aspergillus(5%).Application of RGS and AMF reduced certain disease-causing pathogen like,Fusarium.Highest reduction in Fusarium was recorded in ARGS which reduced Fusarium 32%.Our findings suggested that the integrated use of RGS and AMF in combination is a suitable amendment method for improving the microbial diversity and growth of eggplant.3.Effect of Over Wintering Leafy Vegetable Cropping on Soil Nutrient Dynamics and Microbial Diversity of Continuously Monocropped EggplantPlastic tunnel eggplant monocropping causes the soil erosion,aggravation of soil-borne diseases,decline in crop quality and yield,and the degradation of soil physical and chemical properties which leads to reduction in soil microbes.Thus,the inclusion of winter leafy vegetables cover crops(WLVCCs)is a promising option aimed at better preserving the sustainable production of agricultural systems.In this experiment,Five WLVCCs treatments including a no treated control,welsh onion(W.O),celery,no heading Chinese cabbage(NHC cabbage),and lettuce were grown under a plastic tunnel in a randomized complete block design from mid-November to mid-March,and followed by an eggplant.The objective of this study was to investigate the short-term effect of WLVCCs on soil nutrients and soil microbial community structure.Short term rotation of cover crops significantly improves soil organic carbon and soil organic matter.However,it reduces soil nutrients.Furthermore,Illumina Mi Seq analysis was used to analyze soil microbial diversity and structure in the five different treatments.At Bacterial level total of 56,229 reads were identified,and rarefaction analysis showed that the soil treatments were equally sampled.Our results showed that growing of WLVCCs in fallow period increased bacterial and fungal diversity indices.Furthermore,WLVCCs increased several beneficial bacteria which are involved in promoting plant growth and suppressing soil born disease,like Bacillus,Lysobacter Galliea.Moreover,ITS fungal regions revealed significant diversity among the different treatments with genera like Mortierella(20%),Acremonium(10%)Fusarium(4%)showing higher abundance.WLVCC increased beneficial fungi such as Mortierella,Gibberella,and Remersonia significantly suppressed the abundance of different pathogen which cause different diseases in eggplant like Fusarium,Verticillium and Botrytis.Therefore,from this study we can conclude that NHC cabbage and celery can be successfully grown during winter fallow period to improve soil quality and increase yield of eggplant under plastic tunnel cultivation.