Procam have been working with a number of no-till farmers to look at ways of maximising crop yields whilst reducing inputs. One of the key areas which Procam have been looking at is the use of growth promoting bacteria and fungi to help stimulate root development and increase nutrient and water uptake by the crop. One such trial now in its second year, has been looking at the potential of modern varieties of wheat to be colonised by arbuscular mycorrhizal fungi and the benefits of this association.
Approximately 74% of flowering plants form associations with arbuscular mycorrhizal fungi (AMF), which require a plant host to survive, and the colonisation of plant roots by AMF has been shown to have a number of plant benefits, including; increasing plant uptake of nutrients and water, increasing a plants’ tolerance to both biotic (pathogen infection) and abiotic (drought) stresses and improving soil structure through the release of the protein glomalin.
However any current farming practices have depleted the natural levels of AMF in the soil, through the use of some pesticides and fertilisers to which they are sensitive, growing crop species such as oilseed rape, or sugar beet which are non-mycorrhizal and through cultivation practices where their hyphal network is damaged. No-till farming practices are a good environment for the re-development of natural mycorrhizal populations, and we have seen this on our trial farm down in Essex, which has very high background levels of AM fungi.
The trial I conducted on behalf of Procam, wanted to assess not only the ability o modern wheat varieties to be colonised by AM fungi, but also to assess any potential differences in varietal colonisation levels which might help us to be able to identify varieties best suited to the no-till growing system. The trial took place on a farm down in Essex which has been practicing no-till for over 10 years and with soils which had been tested and found to have high background levels of mycorrhizae present within the field.
A total of nine different varieties of wheat, plus the farmers’ own group 4 wheat variety blend were drilled in the autumn of 2016, following lucerne. The wheat was taken through to harvest with assessments made in March, when the plants were tillering and in July just before the crop was harvested, on the level of AMF colonisation seen. Colonisation levels were assessed by staining the wheat roots with a dye which binds to the AMF structures within the root cells, allowing me to visually assess the proportion of the root samples which were colonised.
The images in figure.1 are examples, taken using a microscope showing some AM fungi structures found in stained wheat roots at the assessment timings in March (A) and July (B). AMF structures have been stained dark blue, whilst plant cells remain white/ light blue. The results from the first year of the trial showed us that all the varieties of wheat tested were capable of AMF colonisation, although the levels of colonisation varied between varieties (figure.2). There was an overall increase in the level of AMF colonisation within the wheat roots from March to July and this is likely due to AM fungi becoming more active as temperatures increase and could also explain the lower variability in colonisation levels between varieties in the samples taken in July, as those less mycorrhizal varieties had a chance to ‘catch-up’.
Of all the varieties trialled KWS Bassett and KWS Silverstone appeared to be the most mycorrhizal, with KWS Silverstone having double to five times the proportion of root area colonised, compared to the other varieties at the March sample timing. This gap had reduced by the July sample timing and it was KWS Bassett that had the highest level of colonisation at this timing, although KWS Silverstone still had the second highest level of colonisation, suggesting that these two varieties are potentially the best to grow in no-till systems.
A second year of the trial is currently on-going, with most of the same varieties being tested, to try and see if the results of last year’s trial are replicable. Procam will be at Groundswell this year on 27th-28th June, at stand E5 in the pasture field, where I or my colleagues will be able to give more information out about our work on AMF, including some preliminary results from the second year of the wheat trial and our work with other biologicals, and our other no-till trials.