Lower fertilizer applications with the help of fungi

Posted Apr 11, 2016 by Tim Sandle
With concerns about the use of chemical fertilizers being discussed in both the U.S. and Europe, news that fungi might present an alternative means for improving crop yields has been welcomed by scientists and policy makers.
A symbiotic relationship exists between plants and fungi. Plants share some of the carbohydrates they generate with the types of fungi that colonize their roots (termed arbuscular mycorrhizal fungi.) Most plants can distinguish between good and bad fungal behaviour, and allocate key nutritional resources accordingly.
In turn, these fungi exchange nitrogen and phosphorous. What if this relationship could be enhanced? Could it lead to a state where artificial chemical fertilizers are no longer required? This is in the context of concerns with glyphosate, which is the active ingredient in several herbicides, as well as being found in the most commonly used herbicides worldwide.
These are questions considered by Professor Heike Bücking, who works at the South Dakota State University’s Department of Biology and Microbiology. Professor Bücking is of the view that the fungal-plant relationship could be exploited in order to increase crop yield, and to make agriculture more environmental sustainable.
Key to the process is determining which fungi are beneficial to plants, and then, looking to see which of these fungi are most beneficial of all. If these can be seeded into soils where valuable crops are growing, then the presence of the appropriate fungi can, as shown in trials, enhance yield without the need for chemicals.
The research has been published in the journal Agronomy. The paper is headed “Role of Arbuscular Mycorrhizal Fungi in the Nitrogen Uptake of Plants: Current Knowledge and Research Gaps.”
In related news, botanists have located the area of genomes within nitrogen-fixing bacteria in roots (rhizobia) that are being altered when the plant is exposed to nitrogen fertilizer. This research could lead to a lowering of the amount of nitrogen fertilizer used, provided the correct bacteria are in abundance. Controlled studies have found this to be beneficial to plants like clover, beans, peas, soybeans and lentils.
This study is expanded upon in the journal Proceedings of the Royal Society B: Biological Sciences (see: “Ecological genomics of mutualism decline in nitrogen-fixing bacteria..”)