scholarly journals Intercropping Alters the Soil Microbial Diversity and Community to Facilitate Nitrogen Assimilation: A Potential Mechanism for Increasing Proso Millet Grain Yield

2020 ◽  
Vol 11 ◽  
Author(s):  
Ke Dang ◽  
Xiangwei Gong ◽  
Guan Zhao ◽  
Honglu Wang ◽  
Aliaksandr Ivanistau ◽  
...  

Intercropping of cereals and legumes has been used in modern agricultural systems, and the soil microorganisms associated with legumes play a vital role in organic matter decomposition and nitrogen (N) fixation. This study investigated the effect of intercropping on the rhizosphere soil microbial composition and structure and how this interaction affects N absorption and utilization by plants to improve crop productivity. Experiments were conducted to analyze the rhizosphere soil microbial diversity and the relationship between microbial composition and N assimilation by proso millet (Panicum miliaceum L.) and mung bean (Vigna radiata L.) from 2017 to 2019. Four different intercropping row arrangements were evaluated, and individual plantings of proso millet and mung bean were used as controls. Microbial diversity and community composition were determined through Illumina sequencing of 16S rRNA and internal transcribed spacer (ITS) genes. The results indicated that intercropping increased N levels in the soil–plant system and this alteration was strongly dependent on changes in the microbial (bacterial and fungal) diversities and communities. The increase in bacterial alpha diversity and changes in unique operational taxonomic unit (OTU) numbers increased the soil N availability and plant N accumulation. Certain bacterial taxa (such as Proteobacteria) and fungal taxa (such as Ascomycota) were significantly altered under intercropping and showed positive responses to increased N assimilation. The average grain yield of intercropped proso millet increased by 13.9–50.1% compared to that of monoculture proso millet. Our data clearly showed that intercropping proso millet with mung bean altered the rhizosphere soil microbial diversity and community composition; thus, this intercropping system represents a potential mechanism for promoting N assimilation and increasing grain yield.

2020 ◽  
Vol 100 (6) ◽  
pp. 683-691
Author(s):  
Xiao-Ming Chen ◽  
Qi Zhang ◽  
Shao-Min Zeng ◽  
Yao Chen ◽  
Yong-Yan Guo ◽  
...  

The use of rain shelters in pear cultivation has been shown to improve yields and the appearance and quality of fruit, as well as reduce diseases and pests; however, how rain shelters affect soil chemical properties, soil enzyme activity, and soil microbial diversity remains unknown. Here, we studied pear trees under rain-shelter cultivation and open-field cultivation in the same orchard and compared fruit quality, soil chemical characteristics, soil enzyme activity, and soil microbial diversity. Results showed that rain shelters can significantly (p < 0.05) increase the sugar content (sweetness) of pear fruits and decrease the content of acids. The levels of available phosphorus, available potassium, organic matter, and water in soils under rain shelters were significantly (p < 0.05) lower than in soils in open fields. Rain-shelter treatment increased soil polyphenol oxidase activity and decreased phosphomonoesterase, urease, and sucrase activity. Analysis of microbial carbon-source utilization rates and microbial diversity showed that open-field cultivation is beneficial for microbial carbon-source utilization and microbial diversity in rhizosphere soil. Our study found that rain-shelter cultivation is not beneficial to soil fertility, microbial carbon-source metabolism and utilization, matter cycling, or microbial diversity and that the use of rain shelters may require appropriate nutrient and organic matter supplementation to maintain long-term cultivation of crops; whereas, the effects of environmental factors on open-field cultivation are greater, and more refined water and fertilizer management is required to improve fruit quality.


2020 ◽  
Author(s):  
Laura Stefan ◽  
Martin Hartmann ◽  
Nadine Engbersen ◽  
Johan Six ◽  
Christian Schöb

SummaryIntensive agriculture has major negative impacts on ecosystem diversity and functioning, including that of soils. The associated reduction of soil biodiversity and essential soil functions, such as nutrient cycling, can restrict plant growth and crop yield. By increasing plant diversity in agricultural systems, intercropping could be a promising way to foster soil microbial diversity and functioning. However, plant–microbe interactions and the extent to which they influence crop yield under field conditions are still poorly understood. In this study, we performed an extensive intercropping experiment using eight crop species and 40 different crop mixtures to investigate how crop diversity affects soil microbial diversity and functions, and whether these changes subsequently affect crop yield. Experiments were carried out in mesocosms under natural conditions in Switzerland and in Spain, two countries with drastically different soils and climate, and our crop communities included either one, two or four species. We sampled and sequenced soil microbial DNA to assess soil microbial diversity, and measured soil basal respiration as a proxy for soil activity. Results indicate that in Switzerland, increasing crop diversity led to shifts in soil microbial community composition, and in particular to an increase of several plant-growth promoting microbes, such as members of the bacterial phylum Actinobacteria. These shifts in community composition subsequently led to a 15 and 35% increase in crop yield in 2 and 4-species mixtures, respectively. This suggests that the positive effects of crop diversity on crop productivity can partially be explained by changes in soil microbial composition. However, the effects of crop diversity on soil microbes were relatively small compared to the effects of abiotic factors such as fertilization (3 times larger) or soil moisture (3 times larger). Furthermore, these processes were context-dependent: in Spain, where soil resources were limited, soil microbial communities did not respond to crop diversity, and their effect on crop yield was less strong. This research highlights the potential beneficial role of soil microbial communities in intercropping systems, while also reflecting on the relative importance of crop diversity compared to abiotic drivers of microbiomes, thereby emphasizing the context-dependence of crop–microbe relationships.


2021 ◽  
Author(s):  
Liuting Zhou ◽  
Jianjuan Li ◽  
Chen Zhang ◽  
Xinlai Guo ◽  
Wei Chu ◽  
...  

Abstract The aim of this study was to explore the soil microbial variability within different forest ecosystems (evergreen broad-leaf forest (EBF), coniferous forest (CF), subalpine dwarf forest (SDF) and alpine meadow (AM) at different altitudes in mid-subtropics of China. The phospholipid fatty acid (PLFA) method was used to analyze the microbial communities in rhizosphere soil under different forest types. The relationships were also analyzed between the microbial diversity and soil nutrients. A total of 27 PLFA biomarkers were detected and the PLFA concentrations decreased in the sequence of bacteria > fungus > actinomycete > protozoa in all forest types. The microbial communities in the soil under all forest types were distinct. The predominant microflora in all soils were 18:1ω9c, 16:1ω7c, cy19:0, a17:0 and 18:0. The indexes of Simpson, Shannon-Wiener and Brillouin of soil microbial community diversity in these four forest types all showed a trend of EBF > CF > SDF > AM. According to principal component analyses (PCA), the variable variances of principal components 1 and 2, which were related to the PLFA biomarkers of soil microorganisms, were 67.67% and 17.91%, respectively. Furthermore, the total PLFAs of different soil microbial groups showed a correlation with soil nutrients and enzyme activities in all forest types. The soil microbial diversity gradually decreased in the order of EBF > CF > SDF > AM in the Daiyun Mountains. Different vegetation types affect soil microbial community composition and diversity by changing the soil physicochemical properties and enzyme activity.


2021 ◽  
Vol 12 ◽  
Author(s):  
Laura Stefan ◽  
Martin Hartmann ◽  
Nadine Engbersen ◽  
Johan Six ◽  
Christian Schöb

Intensive agriculture has major negative impacts on ecosystem diversity and functioning, including that of soils. The associated reduction of soil biodiversity and essential soil functions, such as nutrient cycling, can restrict plant growth and crop yield. By increasing plant diversity in agricultural systems, intercropping could be a promising way to foster soil microbial diversity and functioning. However, plant–microbe interactions and the extent to which they influence crop yield under field conditions are still poorly understood. In this study, we performed an extensive intercropping experiment using eight crop species and 40 different crop mixtures to investigate how crop diversity affects soil microbial diversity and activity, and whether these changes subsequently affect crop yield. Experiments were carried out in mesocosms under natural conditions in Switzerland and in Spain, two countries with drastically different soils and climate, and our crop communities included either one, two or four species. We sampled and sequenced soil microbial DNA to assess soil microbial diversity, and measured soil basal respiration as a proxy for soil activity. Results indicate that in Switzerland, increasing crop diversity led to shifts in soil microbial community composition, and in particular to an increase of several plant-growth promoting microbes, such as members of the bacterial phylum Actinobacteria. These shifts in community composition subsequently led to a 15 and 35% increase in crop yield in 2 and 4-species mixtures, respectively. This suggests that the positive effects of crop diversity on crop productivity can partially be explained by changes in soil microbial composition. However, the effects of crop diversity on soil microbes were relatively small compared to the effects of abiotic factors such as fertilization (three times larger) or soil moisture (three times larger). Furthermore, these processes were context-dependent: in Spain, where resources were limited, soil microbial communities did not respond to crop diversity, and their effect on crop yield was less strong. This research highlights the potential beneficial role of soil microbial communities in intercropping systems, while also reflecting on the relative importance of crop diversity compared to abiotic drivers of microbiomes and emphasizing the context-dependence of crop–microbe relationships.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2459 ◽  
Author(s):  
Silvia Pajares ◽  
Ana E. Escalante ◽  
Ana M. Noguez ◽  
Felipe García-Oliva ◽  
Celeste Martínez-Piedragil ◽  
...  

Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content) at local scale (meters) occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m2plot and: (a) characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b) determined soil chemical parameters, and (c) identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca2, K+) and anions (HCO${}_{3}^{-}$, Cl−, SO${}_{4}^{2-}$) content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.


2021 ◽  
Vol 22 (7) ◽  
pp. 3438
Author(s):  
Juan Liu ◽  
Xiangwei He ◽  
Jingya Sun ◽  
Yuchao Ma

Bacterial communities associated with roots influence the health and nutrition of the host plant. However, the microbiome discrepancy are not well understood under different healthy conditions. Here, we tested the hypothesis that rhizosphere soil microbial diversity and function varies along a degeneration gradient of poplar, with a focus on plant growth promoting bacteria (PGPB) and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG (antibiotics resistance genes) annotation revealed that available potassium (AK) was correlated with microbial diversity and function. We proposed several microbes, Bradyrhizobium, Sphingomonas, Mesorhizobium, Nocardioides, Variovorax, Gemmatimonadetes, Rhizobacter, Pedosphaera, Candidatus Solibacter, Acidobacterium, and Phenylobacterium, as candidates to reflect the soil fertility and the plant health. The highest abundance of multidrug resistance genes and the four mainly microbial resistance mechanisms (antibiotic efflux, antibiotic target protection, antibiotic target alteration, and antibiotic target replacement) in healthy poplar rhizosphere, corroborated the relationship between soil fertility and microbial activity. This result suggested that healthy rhizosphere soil harbored microbes with a higher capacity and had more complex microbial interaction network to promote plant growing and reduce intracellular levels of antibiotics. Our findings suggested a correlation between the plant degeneration gradient and bacterial communities, and provided insight into the role of high-turnover microbial communities as well as potential PGPB as real-time indicators of forestry soil quality, and demonstrated the inner interaction contributed by the bacterial communities.


2021 ◽  
Vol 9 (7) ◽  
pp. 1400
Author(s):  
Marta Bertola ◽  
Andrea Ferrarini ◽  
Giovanna Visioli

Soil is one of the key elements for supporting life on Earth. It delivers multiple ecosystem services, which are provided by soil processes and functions performed by soil biodiversity. In particular, soil microbiome is one of the fundamental components in the sustainment of plant biomass production and plant health. Both targeted and untargeted management of soil microbial communities appear to be promising in the sustainable improvement of food crop yield, its nutritional quality and safety. –Omics approaches, which allow the assessment of microbial phylogenetic diversity and functional information, have increasingly been used in recent years to study changes in soil microbial diversity caused by agronomic practices and environmental factors. The application of these high-throughput technologies to the study of soil microbial diversity, plant health and the quality of derived raw materials will help strengthen the link between soil well-being, food quality, food safety and human health.


2021 ◽  
Author(s):  
Felipe Bastida ◽  
David J. Eldridge ◽  
Carlos García ◽  
G. Kenny Png ◽  
Richard D. Bardgett ◽  
...  

AbstractThe relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity–biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.


2021 ◽  
Vol 168 ◽  
pp. 104160
Author(s):  
Yang You ◽  
Jingfei Ren ◽  
Jing Wu ◽  
Zhouwen Ma ◽  
Yongchao Gu ◽  
...  

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