Effects Of Soil Amendment With Raw Garlic Stalk,AMF And Growing Overwinter Leafy Vegetables On Eco-physiology Of Continuous Cropping Cucumber Under Plastic Tunnel Cultivation

Cucumber double cropping system is a typical intensive production model under plastic-greenhouse cultivation in North China.This has been characterized as a nutrient exhaustive system that requires more intensive management and high plant nutrition for increasing crop yield.Consecutive monoculture is the core cropping system that have been accelerated by long-term anthropic inputs and manipulative treatments.Cucumber is one of the main cash vegetable crop which adversely suffered from continuous cropping obstacles and is considered as a major limiting factor of crop yield reduction and soil quality deterioration.The escalated negative soil-plant feedback due to site-specific continuous cropping obstacles could be attenuated by adopting sustainable and cost-effective agronomic measures.Underlying mechanism of crop yield,soil quality changes and soil biota structure through compatible soil organic inputs and cropping system is,however,less understood.Current research work was carried out to investigate the effect of organic amendments and diversified cropping system on the alleviation of soil related continuous cropping obstacles and cucumber production constraints with biological and ecological mechanism.1.Effects of soil amendment garlic stalk on soil physicochemical propertiesand microbial community and continuous cropped cucumberSustainable agriculture with organic amendments requires cost-effective ways to restore soil microbial diversity in order to maximize productivity without increasing input costs,particularly under intensive cropping systems.The short-term preliminary pot experiment was carried out to check the response of garlic stalks as a soil amendment.Garlic stalks were applied at different rates of 1%,3% and 5% in a replanted degraded soil that had been used for continuous cucumber monoculture for 7 years(annual double cropping system in a plastic tunnel).The results obtained indicated that higher amount of C-amended garlic stalks(5%)enhanced the plant morphology such as plant height,leaf area,and shoot fresh and dry weight biomass.The addition of the garlic stalks to the pots resulted in considerable improvement in the formation of leaf photosynthetic pigments in comparison to the control plants.The soil pH moderately changed and significantly increased soil organic matter(SOM),nutrients availability,enzymatic activities and cucumber yield by 20% as compared to non-amendment.Using Illumina Mi Seq sequencing analysis of the 16 S rRNA and 18 S rRNA genes,this study revealed that 3% of garlic stalk application resulted in the increased bacterial richness and phylogenetic diversity over fungi.In addition,a heatmap analysis illuminated that the soil pH(**p< 0.01),OM(**p< 0.01),available P(*p < 0.05),available K(*p< 0.05;**p0.01)and invertase activity(*p < 0.05)were the most significant factors that correlated with the abundant community distribution of soil bacteria and fungi.To the best of our knowledge,this is the first preliminary study that focuses on locally available,economically possible and good quality crop residue-based restoration of degraded soil in short duration for intensifying the cucumber cultivation without yield loss.2.Effects of soil amendment garlic stalk and AMF on soil AMF community and continuous cropped cucumber growth and fruit qualityTraditionally mono-cropped cucumber repetition in the same field of stressed soil is likely to be vulnerable to soil-related disorders,such as soil sickness,soil-borne pathogens,and the accumulation of autotoxins.Arbuscular mycorrhizal fungi(AMF)is the most efficient natural plants stimulants that has widespread biochemical,phonological,ecological and agrotechnical significance.However,their role in crop growth improvement in the presence of organic amendments and their co-occurrence pattern of the community composition associated with cucumber productivity is infrequently reported especially for greenhouse production system.In this study,25 g of indigenous AM strain,i.e.,Glomus versiforme L.,and 5% of garlic stalk(GS)application were assessed for crop productivity feedback in a degraded and replanted soil of plastic greenhouse(2016–2018).We found that repetitively adding AM inocula with organic substrates(GS)improved the cucumber growth and physiology.The useful trait of AM symbiosis with C-amended organic substrates preferentially manifested as increased root colonization,hyphal density proliferation,AM sporulation,and root activity,and suppressed Fusarium incidence.The post AM development further prevailed the synergistic interaction,and the co-inoculation effect resulted in an increase in fruit nutrition uptake,seasonal cucumber yield and fruit quality attributes.Illumina Mi Seq analysis of the 18 S rRNA gene amplicons revealed the garlicAM-mediated changes on the assemblage of the Glomeromycotan community composition and diversity.Dominant AM genera that are particularly enriched with the Glomus taxon may be important ecological drivers associated with plant productivity and fruit quality characteristics.In addition,the garlic-AM mutualistic association with a compatible host interaction provided novel allelopathic insights and challenged the ambiguous hypothesis that a particular fungal strain may not work effectively in the vicinity of organic substrates that are typically derived from allelopathic sources.These results suggest that the AMorganic substrate association might be a pragmatic option for use as an economic and efficient biological resource and as a new sustainable test measures to enhance the ecosystem services and plant productivity of the anthropogenic plastic greenhouse cultivation.3.Effects of soil amendment garlic stalk and AMF on soil quality,bacterial diversity and continuous cropped cucumberFurther we studied the priming effects of soil amendments through addition of indigenous organic substrate(GS: garlic stalk)and mycorrhizal inoculants(AMF: Glomus versiforme L.)in continuous planted soil.We found that repeated application of co-amended GS+AMF treatment significantly induced the soil quality changes by increasing organic matter,soil nutrient contents and biological activity and thus cucumber yield.The additive effect of GS amendment unveiled the structural development of AMF characteristics;trigger the mycorrhizal strength via co-inoculation,sporulation,extend the hyphal growth and facilitate the mutualistic coordination to acquired host-compatible symbiosis.Our 16 S rRNA metagenomic coupled with PCA and NMDS analysis revealed the distinctive role of organic amendments in shaping the community structure and composition.In particular,the bacterial diversity was more conducive and sensitive to sole organic substrate,delineated the highest richness and diversity indices(ACE and Chao)under GS amended soil.Redundancy analysis suggested that the predominant taxa was influenced directly by the GS,AMF,GS+AMF applied,and indirectly by soil edaphic variables.Soil pH with biological activation was the important predictor for structure of the soil bacterial community in our cropping system.In addition,our predictive metabolic characteristics(metabolism)associated with host-plant symbiosis could be an important ecological signal to alleviate the continuous cropping obstacle.Results from the present study suggest well-adopted garlicAM symbionts in this cultivation system.It is concluded that the consequent positive synergistic interaction is the key mechanism of induced soil quality environment resulting from applied organic substrate and AMF inoculation,which ultimately can promote the seasonal crop yield and mediate soil microbial activity under anthropogenic degraded soil.4.Effect of winter catch leafy vegetables on soil microbial community and continuous cropped cucumber yieldAgricultural management practices and cropping systems can evidently influence plant biodiversity,soil health and productivity through triggering the soil biochemical modification and soil microbial activity/composition.In field experiment,leafy vegetables as cover crops were grown during over-winter fallow period in seasonal cucumber cultivation to demonstrate the comparative evaluation of cover cropping effect in plant-soil-microbe analysis.Results from Illumina high-throughput sequencing of 16 S rRNA genes indicated that the soil bacterial community composition and diversity greatly changed through changes in the soil properties under cover cropping system.The soil biological characteristics were significantly induced by cropping system.The highest cucumber yield was recorded under SC(spinach-cucumber)cropping system in winter-spring season,whereas NCCC(nonheading Chinese cabbage-cucumber)cropping system exhibited the highest mean fruit yield during autumn-winter season,respectively than FC planting system(fallow-cucumber).PCA coupled with NMDS analysis revealed that the cover planting shaped soil microbiome more greatly than the FC(fallow-cucumber)planting system.Quantitative analysis of LEf Se indicated that Proteobacteria,Actinobacteria,Bacteroidetes,and Acidobacteria were the potentially functional and active soil microbiome.Rhizosphere of cover planting systems is a hotspot for metabolic capabilities of abundant functional genes,compared to FC.In addition,the predictive metabolic characteristics(metabolism and detoxification)associated with host-plant symbiosis could be an important ecological signal that provide direct evidence to mediate the soil structure stability.Interestingly,the plant density of non-heading Chinese cabbage and Spinach species are capable to reduce the adverse effect of arsenic(As)accumulation though increasing the function of arsenate reductase pathway.RDA analysis indicated that relative abundance of the core microbiome can directly and indirectly influenced by certain environmental determinants.These findings stress the importance of studying cover cropping system as an efficient biological tool to protect the soil ecological environment.