Substances from maize roots influence wheat yield

Maize roots secrete certain substances that influence soil quality. In certain fields, this effect increases the yield of wheat planted after the maize in the same soil by more than 4%. Researchers at the University of Bern were able to demonstrate this. The findings from several field experiments show that such effects are highly variable, but that in the long term they could help to make cereal cultivation more sustainable without additional fertilisers or pesticides.

Read the original media release here. (in German)

Plants produce a wealth of specialised chemical substances. Some of these are also released into the soil and thus influence its quality. This in turn affects the next plant that grows in this soil. The extent to which the secreted substances can be used in agriculture to increase productivity has so far been little researched. Researchers from the Institute of Plant Sciences (IPS) at the University of Bern have now carried out field experiments on this. With their findings, published in the journal eLife , the researchers demonstrate that chemical substances from the roots of maize plants can increase the yield of subsequent wheat – and under realistic agricultural conditions.

How maize root substances influence wheat #

Earlier studies by researchers at the Institute of Plant Sciences (IPS) at the University of Bern had shown that benzoxazinoids – chemical substances that maize plants release through their roots – change the composition of microorganisms in the soil around the roots and thus influence the growth of subsequent plants in this soil. The present study investigated whether such plant-soil feedbacks also occur under realistic agricultural conditions. “Such field experiments are essential to test whether basic research can be transferred into practice and thus to test a possible agronomic benefit,” says Valentin Gfeller, who worked on the project as a doctoral student at the IPS and now works at the Research Institute of Organic Agriculture FiBL. In a two-year field experiment, two maize lines were grown first, only one of which released benzoxazinoids into the soil. Three varieties of winter wheat were then grown on the differently conditioned soils. This showed that the release of benzoxazinoids leads to improved emergence, increased tillering, increased growth and higher yield.

Fewer pests, same quality #

In addition to the higher yield, a lower infestation by certain pests was observed. “A yield increase of 4% does not sound spectacular, but it is significant when you consider how difficult it has become to increase wheat yields without additional inputs,” says Matthias Erb, Professor of Biotic Interactions at the Institute of Plant Sciences, who led the study together with Klaus Schläppi from the University of Basel. “Whether such effects really make a difference in large-scale agricultural application remains to be seen, however, as yield also depends on many other factors,” says Erb. The study shows the potential of using specialised plant substances to improve crop productivity through variety-specific crop rotations.

Thanks to collaborations within the University of Bern’s Interfaculty Research Cooperation (IRC) “One Health” (see box), the quality of the wheat could also be examined at the level of individual chemical elements. Together with the Institute of Geography at the University of Bern and Agroscope, the Swiss federal centre of excellence for agricultural research, it was shown that the increase in yield due to benzoxazinoids has no negative effect on the quality of the wheat.

Plant substances persist in the soil #

To better understand the underlying mechanism, the researchers carried out various soil and root analyses. Benzoxazinoid-producing plants accumulated these substances and their breakdown products in the soil close to the roots. In addition, in collaboration with the University of Basel, it was confirmed that benzoxazinoids influence the community of bacteria and fungi in and on the maize roots. However, soil nutrients were not altered. The benzoxazinoids also proved to be particularly long-lived in the soil. The extent to which wheat growth and overall yield are influenced by benzoxazinoids directly or indirectly via the microorganisms in the soil is yet to be investigated in more detail.

Soil characteristics are decisive #

To test the effects of different environmental factors, the research team, together with the University of Basel and Agroscope, investigated in a further two-year field experiment how these benzoxazinoid-driven plant-soil feedbacks behave on a more heterogeneous field. The composition of soil chemistry and microorganisms on this field varied greatly. The researchers were able to show that the influence of benzoxazinoids on the growth and resistance of wheat depends on this varying composition. “A better understanding of the effects of soil characteristics on plant-soil feedbacks is crucial for their future use in sustainable agriculture,” says Valentin Gfeller.