Research Indicates Mycorrhizal Fungi Can Boost Plant Yields by 40 Percent

By 2050, the global population is expected to exceed 9 billion, and as environmental concerns persist, traditional farming methods just aren’t making the cut for long-term agricultural practices. One in ten people struggle with food insecurity, despite 38 percent percent of global land surface being used for agriculture using approximately 70 percent of global freshwater.

Practices like monocropping and tilling have damaged over a third of the world’s topsoil, which is necessary for crop growth. At this rate, the earth could run out of usable topsoil in about 60 years. The impacts of climate change, such as inconsistent weather patterns and severe events like floods and droughts, only worsen this situation.

Fortunately, fungi offer a glimmer of hope in the quest to meet the needs of a rapidly growing population while also protecting the planet’s ecological balance. A recent study has found that mycorrhizal fungi can increase plant yields by up to 40 percent.

This discovery can enhance the resilience and growth of crops while reducing reliance on chemical fertilizers and intensive irrigation, offering a promising solution that could revolutionize modern farming practices.

Importance of mycorrhizal fungi

Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most terrestrial plants. Thread-like fungal structures called hyphae penetrate the outer layers of a plant’s roots and within the cell’s inner membranes.

Since this process extends the roots, the plant’s nutrient uptake is enhanced, and the fungi supply them with water, phosphorus, nitrogen, and other essential nutrients from the soil. In return, the plant provides the fungi with carbohydrates that are produced during photosynthesis.

Plants with healthy and well-established mycorrhizal networks often demonstrate improved resistance to drought and root pathogens since the fungi form a protective barrier against soil-borne diseases. Previous studies have shown promising evidence that a wide range of crops inoculated with AMF have enhanced growth rates. AMF has also been shown to maintain and improve healthy soil structure and nutrient retention (1). 

There are two different ways for AMF to benefit agricultural soils. Native AMF can be promoted and maintained with sustainable agricultural practices like crop diversification, organic farming, and tillage reduction, or AMF can be intentionally introduced into soils with a low abundance of native AMF (2). 

Study background

To accurately measure the impact added AMF has on crop growth, scientists use a metric known as the mycorrhizal growth response (MGR). However, this method is not always consistent because of the varying nature of soils and plant species. The MGR technique is highly unpredictable since there is no certainty that the AMF will successfully settle in the soil or consistently improve crop yields (3). 

Recognizing these limitations, the researchers of the study wanted to develop a more reliable method to predict crop responses to AMF inoculation. The study focused on practical field applications, particularly examining how AMF affected maize, a globally significant crop.

The growth of the maize crops was observed in various agricultural settings to thoroughly analyze the soil environment and determine AMF’s direct impact on the plants. This analysis looked into the diversity and concentration of fungal species and the composition of root microbiomes in the soil post-AMF inoculation. 

Major findings and future research

The study revealed several notable findings that illustrate the promising benefits and challenges of using AMF to enhance crop growth. One of the primary observations was the wide variability in crop growth response to AMF inoculation. In some circumstances, the crop yield increased by up to 40 percent, while in other cases, there was either no notable change or a decrease in yield. As seen with typical MGR measurements, AMF interacts with different soils and plants in a complex nature, indicating a further need for more research.

The study also found that the soil microbiome is a primary predictor of how successful AMF inoculation is. Fields with a higher presence of fungal pathogens showed the most significant benefits from adding AMF. The AMF acted as a protective barrier against the pathogens, which helped maintain and occasionally boost crop yields, demonstrating the protective role of AMF against soil-borne diseases.

Through the information gathered in the study, the researchers developed a predictive model to forecast the effectiveness of AMF inoculation. By analyzing diverse soil parameters and the microbiome, they could predict the inoculation success in a majority of the crop fields. This major breakthrough will help in future strategies for the efficient and targeted use of AMF in agricultural practices. 

According to  Klaus Schläppi, one of the study’s co-lead researchers, “With just a few soil indicators—mainly soil fungi—we were able to predict the success of inoculation in nine out of 10 fields, and thus could also predict the harvest yield even before the field season.”

Furthermore, the study discussed the positive impacts of AMF on soil health and crop resilience against climate change challenges. AMF inoculation was found to enhance nutrient uptake and offer protection against environmental stressors.

However, the study also acknowledged the several difficulties that occur when applying AMF inoculation on a large scale. Since the crop response is so unpredictable and site-specific application strategies would make widespread adoption complex, the study calls for more research to simplify and optimize the process across different agricultural settings. Still, “the results of this field trial represent a big step toward a more sustainable agriculture,” says co-lead Marcel van der Heijden.

References

1. Cavagnaro, Timothy R., S. Franz Bender, Hamid R. Asghari, and Marcel G.A. van der Heijden. 2015. “The Role of Arbuscular Mycorrhizas in Reducing Soil Nutrient Loss.” Trends in Plant Science 20 (5): 283–90. https://doi.org/10.1016/j.tplants.2015.03.004.
2. Lutz, Stefanie, Natacha Bodenhausen, Julia Hess, Alain Valzano-Held, Jan Waelchli, Gabriel Deslandes-Hérold, Klaus Schlaeppi, and Marcel G. A. van der Heijden. 2023. “Soil Microbiome Indicators Can Predict Crop Growth Response to Large-Scale Inoculation with Arbuscular Mycorrhizal Fungi.” Nature Microbiology 8 (12): 2277–89. https://doi.org/10.1038/s41564-023-01520-w.
3. Zhang, Shujuan, Anika Lehmann, Weishuang Zheng, Zhaoyang You, and Matthias C. Rillig. 2018. “Arbuscular Mycorrhizal Fungi Increase Grain Yields: A Meta‐Analysis.” New Phytologist 222 (1): 543–55. https://doi.org/10.1111/nph.15570.