Co-Amended Synergistic Interactions between Arbuscular Mycorrhizal Fungi and the Organic Substrate-Induced Cucumber Yield and Fruit Quality Associated with the Regulation of the AM-Fungal Community Structure under Anthropogenic Cultivated Soil.

Ahmad Ali,Yang Fan,Haiyan Ding,Muhammad Ghani,Muhammad Iqbal,Zhihui Cheng

doi:10.3390/ijms20071539

Abstract

Monotonous cucumber double-cropping systems under plastic greenhouse vegetable cultivation (PGVC) previously intensified by long-term anthropogenic activities and manipulative treatments leads to a crop productivity reduction and soil biota disturbances. In this study, the role of the indigenous arbuscular mycorrhizal strain (AM: Glomus versiforme L.) and organic substrate (GS: Garlic stalk) application were assessed for plant microbe interaction and crop productivity feedback in a greenhouse (2016–2018) under a cultivated Anthrosol characterized as a replanted degraded soil. 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, 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 MiSeq analysis of the 18S rRNA gene amplicons revealed that the dominant AM genera that are particularly enriched with the Glomus taxon may be important ecological drivers associated with plant productivity and fruit quality characteristics. These results suggest that the AM-organic substrate association might be a pragmatic option for use as an economic and efficient biological resource and as a newly-sustainable plant microbe mediator to enhance the regional ecosystem services and plant productivity of the anthropogenic PGVC of this region.

Highlights

Northern plastic greenhouse vegetable cropping (PGVC) has intensified greatly since 1980 with an area of 2,900,000 ha in 2010 contributing >33% of the total vegetable cultivation across the mainland production [1,2,3]
The objectives of this study were: (1) To concomitantly estimate the physiological improvement and the associated mycorrhizal development induced by the repeated addition of Arbuscular mycorrhizal fungi (AMF) or organic substrate under anthropogenic PGVC soil; (2) to predict the co-inoculation synergistic interaction for cucumber productivity feedback if the arbuscular mycorrhizal strain (AM) examined is adaptable via inoculation induced by applied organic substrates; (3) to elucidate the distribution pattern of AMF communities across the soil samples under single or dual or non-treatment applications, and (4) to reveal the garlic stalk (GS)-AM-mediated changes or assemblage in microbial community composition and diversity associated with subsequent fruit yield and quality traits
The continuous addition of either AMF inoculum or garlic stalk (GS) as an organic substrate had a significant impact on the cucumber growth parameters in the anthropogenic soil substrate

Summary

Introduction

Northern plastic greenhouse vegetable cropping (PGVC) has intensified greatly since 1980 with an area of 2,900,000 ha in 2010 contributing >33% of the total vegetable cultivation across the mainland production [1,2,3]. Monotonous cropping systems of more than seven years of continuous cucumber cultivation with conventional management practices are usually considered the major limiting element resulting in a 50% reduction of the total plant biomass, a decline of 31–42% in soil organic matter (SOM) and invasion of the cucumber seedlings with Fusarium oxysporum in the northern PGVC of China [9,10] These cumulative anthropogenic factors occurring over many years drastically disrupted the soil microbial community membership, soil structure instability, and appeared to be the common cause of inferior plant growth, fruit quality deterioration, soilborne disease development and soil biota disturbances [11,12]

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