Harnessing Plant Growth-Promoting Microorganisms for Sustainable Crop Production

27 Oct 2021

Successful Field Trials taking place in SIMBA

SIMBA partners at ENEA have been examining the application of plant growth-promoting microorganisms (PGPMs), the so-called ‘plant probiotics’. In agricultural production, PGMPs have the potential to provide healthy food in a sustainable manner by reducing the amount of fertilisers, pesticides and herbicides needed, even under stressful environmental conditions. However, compared to laboratory studies, the limited reproducibility of beneficial microbial effects in the field remains a considerable challenge for the successful use of PGPMs in agriculture. To address this issue, one potential strategy is to develop and apply multifunctional microbial consortia, taking advantage of stable synergistic effects and increased flexibility of responses under different environmental conditions.

As part of WP2 in SIMBA, microorganisms with proven plant-growth promoting (PGP) potential were selected and tested for their in vitro compatibility.  By combining compatible microorganisms with different PGP properties, three multifunctional synthetic microbial consortia (MC_A, MC_B and MC_C) were developed to be used as inoculants for maize, wheat, tomato and potato in greenhouse and field settings for improving crop yield and quality. Moreover, suitable bioactive compounds were identified to act as biostimulants in combination with selected microbial consortia. This research was published in a paper in the journal Microorganisms in February of this year.

After the previous set-up of delivery methods in greenhouse and growth chamber conditions, the new microbial consortia were trialled as part of field trials in Germany (organic conditions) and in Italy (organic and conventional conditions). During the vegetation period, different plant growth parameters (such as plant height, stem diameter, plant biomass production, nutrient content and uptake), as well as different spectrophotometric data on plant leaves were regularly assed in order to characterize microbial-mediated differences in plant growth and development.

The following pictures (Figures 1-4) give an overview of the field experiment in Germany.

Fig. 1 Seed coating of maize seeds prior to sowing with different microbial consortia.

Fig. 2 Maize sowing with inoculated maize seeds.

Fig. 3 Maize irrigation (left), maize weeding with goose foot and finger hoe (middle), soil sampling procedure for soil chemical analysis (right).

Fig. 4 Data collection: Crop stand density (left), plant length (middle) and stem diameter (right) assessments.

The following pictures (Figures 5-7) give an overview of the field experiment in Italy on maize and tomato.

Fig 5: Images of wheat (Svevo and Bramante) taken at different growing stages.

Treatments were as follows: control, Arbuscolar Mychorrizal Fungi (AMF, Myc Agro), Micosat F (CCS Aosta), MC_B + AMF, MC_C + AMF, with and without biochar.


Fig 6: Corn field at different stages (in May, June and July).

Fig 7: Images from three tomato fields in Italy in different environments, two in organic, one in conventional.

Treatments were as follows: control, char, char + Arbuscolar Mychorrizal Fungi (AMF, Myc Agro), char + MC_B + AMF and char + Micosat (CCS Aosta).

These investigations were completed by the collection of bulk and rhizosphere soil samples at different growth stages in order to monitor the establishment and continuance of the introduced microbes within the soil as well as the effects of PGPM application on the soil-rhizosphere microbiome.

Ongoing activities and Outlook

Over the coming months, partners from WP2 will investigate the effect of the microbial consortia application on plant microbiome below ground. They will perform DNA extraction using Illumina high throughput sequencing (HTS) and bioinformatic analysis to shed light on rhizospheric microbial community responses to the new microbial inoculants. Understanding these links could help in the production of high-quality microbial inoculants to promote crop productivity. In addition, the replication of field trials in Italy and Germany will allow them to obtain important results on replicability and efficacy of their application under field conditions i.e. in the complex field environment where various players act simultaneously.