Research is shedding new light on a relationship that exists between most plants and some beneficial organisms in the soil.
Biologists are interested in the nature of that partnership and how it affects plants growing in the wild, while other researchers are looking to exploit it, allowing producers to grow crops with fewer inputs.
McMaster University biologist Susan Dudley is examining the growth of a weed, but she said the work could also have implications for farmers.
Dudley, who is attempting to determine if plants can recognize their relatives, studied the relationship between the weed and mycorrhizal fungi.
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The benefits of the fungi are well-documented but aren’t exploited in high-input agriculture.
The fungi provides the plant with pathogen protection and nutrients, particularly phosphorus, in ex-change for carbohydrates.
In a competitive environment, it’s possible for neighbouring plants to benefit from a blossoming fungal network without making the same sacrifices.
The researcher’s greenhouse experiments examined the plant’s social environment, showing how a ragweed plant recognizes its kin and behaves unselfishly, or “altruistically,” as lead author Amanda File describes recently in the journal PLOS ONE.
Ragweed was grown with seeds from the same plant as well as with “stranger” seeds. When grown with “strangers,” the fungal network was smaller and the group observed greater root lesions. Among kin, there was more fungi, which resulted in a greater cost to the plants but also greater benefits.
“We see differences in traits when plants are grown with their siblings compared to strangers,” said Dudey. “The differences we see are evidence of plants being less competitive with their relatives.”
Theory suggests that the same thing occurs in other plant systems, she said.
“By understanding what helps increase productivity in wild plants, where they’re under intense natural selection, then we might be able to come up with ideas about how we can increase productivity in crop plants,” said Dudley.
“Evolutionary biologists are talking about fitness, but fitness is very similar to yield. The amount of carbon a plant can store in a tuber, like a potato, or the number of seeds and the size of the seeds made, we call that fitness, but producers will call that yield. So we have very similar interests.”
Danny Singh, a durum wheat breeder with Agriculture Canada in Swift Current, Sask., said there is potential for large-scale, commercial farms to make better use of these organisms.
He’s studying the compatibility of durum wheat genotypes with mycorrhizal fungi and looking for plants that can capitalize on their presence and possibly require lower phosphorus input.
His efforts have identified how some durum varieties have a greater mycorrhizal dependency.
“What we are looking for are plants that have a better association,” he said. “So they aren’t dependent, but in the right conditions they are better placed and they are more strategic in how they utilize (it).”
A commercial mycorrhizal product, Myke Pro, is available as an in-oculant, but it is used for garden plants. Singh’s goal is to identify cultivars that make the best use of what’s already in the soil.
“Some of our work is showing that Strongfield, for example, seems to be a good choice for that,” he said.
“More work needs to be done to test it against a range of different species and strains because as you can imagine in the soil, there’s a lot of different microorganisms. In researching them, you look at one on one and then you keep adding things. We’re taking small steps.”
