Application of microbial inoculants significantly  enhances crop productivity: A meta‐analysis of studies from 2010 to 2020

Abstract

Introduction: With the rapid development of microbial technology, microbial inoculant is considered as a promising tool in sustainable agricultural systems. Mechanisms by which microbial inoculants improve crop yield include improving plant nutrient availability and alleviating abiotic/biotic stresses (e.g., drought, salt and disease). However, the field efficacy of microbial inoculants remains inconsistent, which constrains large-scale adoptions. Identity of dominant mechanisms that underpin the positive impacts of different microbial inoculants is limited. Thus, a comprehensive quantitative assessment of known inoculants on crop performance is needed to provide guidance for the development of effective microbial tools from both research and commercial perspectives.Materials and Methods: Based on 97 peer-reviewed publications, we conducted a meta-analysis to quantify the benefits of different microbial inoculants on crop yield, and to identify the key mechanisms that underpin enhanced crop yield.Results: Result showed that (i) alleviation of stresses was the major mechanism (53.95%, n = 53) by which microbial inoculants enhance crop yield, while improving plant nutrient availability accounted for 22.25% (n = 58) of crop yield enhancement. (ii) Pseudomonas was the most effective microbial inoculant in enhancing crop yield through alleviating stresses (63.91%, n = 15), whereas Enterobacter was the most effective in improving plant nutrient availability (27.12%, n = 5). (iii) Considering both mechanisms together, Pseudomonas (49.94%, n = 21), Enterobacter (27.55%, n = 13) and Bacillus (25.66%, n = 32) were the largest sources of microbial inoculants to enhance crop yield, and the combination of diazotroph Burkholderia with its legume host had the highest effect on improving the yield (by 196.38%). Microbial inoculants also improve nutritional quality by enhancing mineral contents in the produce. Conclusion:Our analysis provides evidence that microbial inoculants can enhance agricultural productivity and nutritional quality and can be used either alone or in combination with reduced amount of agrochemicals to promote sustainable agriculture.

Do inoculated microbial consortia perform better than single strains in living soil? A meta-analysis

“…Our results showed that bacterial inoculants, in isolation or in a consortium, significantly promoted the functions (i.e., biofertilization and bioremediation) there were selective for when introduced into living soils. For example, applying single species showed an increased effect on plant growth promotion on average by 29%, which is similar to that reported in a recent meta-analysis (J. Li et al, 2022), which suggests the yield increase (32% on average) after the application of microbial inoculants.…”

“…Regarding soil organic matter and available N and P, the observed the significant and positive correlation between their contents and lnRR for biofertilization indicates that providing a soil environment that is relatively rich in nutrients is conducive to the function of inoculated agents. Indeed, a large number of studies have shown that measures such as organic fertilization can promote crop yields by regulating the bioavailability of soil nutrients and functional microorganisms (e.g., P-solubilizing bacteria) (Bi et al, 2020; K. Li et al, 2022).…”

“…The highest effect size was observed when consortia were constructed by combining Bacillus and Pseudomonas , which increased plant growth by 86.6%. These two taxa were reported to be frequently used as microbial inoculants for biofertilization and bioremediation (Santoyo et al, 2021; J. Li et al, 2022; Wu et al, 2022) and may function in a complementary fashion in the soil.…”

Insights into the Methodological, Biotic and Abiotic Factors Influencing the Characterization of Xylem-Inhabiting Microbial Communities of Olive Trees

“…This strategy can be applied to identify key microbial genera associated with particular plant phenotypes (e.g., resistant to vascular plant pathogens [ 5 ]) or by transplanting beneficial bacteria from microbiomes of wild plant genotypes to cropped cultivars [ 72 ]. Such cultured bacterial consortia can also be ideal targets for the design of effective biofertilizers, biostimulants or biocontrol agents for a wide range of crops [ 73 ]. Therefore, the rebirth of microbial culture collections from specific plant ecological niches represents a valuable tool for increasing our understanding of the plant microbiome.…”

Host selection has stronger impact on leaf microbiome assembly compared to land-management practices

“…In general, the host plant releases chemicals and root exudates into the soil which serve as a signal to initiate the recruitment of specific microbes in the rhizosphere, which subsequently enter inside the plant through the root and are then transported across the plant compartments through shoot into leaf, seeds, flower, etc. (Miransari and Smith,2014; Shade et al .,2017, Liu et al ., 2020). The plant microbiome assembly requires mutual recognition where microbes recognize chemical signals produced by the plant to respond, while the plant immune system ensures that only recognized microbes can colonize (Fitzpatrick et al ., 2020).…”