Estimating the AM fungal resources of wheat fields
Date
2012-03-13
Authors
Dai, M.
Sheng, M.
Bremer, E.
He, Y.
Wang, H.
Hamel, C.
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Poster Presentation
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Abstract
The arbuscular mycorrhizal (AM) fungi are a taxonomic group of microscopic soil dwellers
generally promoting the growth of most plant species, including wheat, by mobilizing soil
minerals, in particular soil P. Despite the importance of the AM fungi for plant nutrition, no
technology exists to identify the fields in which AM fungi are doing a good job with feeding P to
crops and the fields where agronomic interventions are required. We set out to fill this gap and
examined 225 commercial fields in 2007, 2009 and 2010. We first found that P yields were
limited by P supply rates below 3.5 μg P 10 cm-2 day-1. Fifty seven percent of the organic fields
surveyed were below this threshold. A trend for higher P use efficiency in organic than
conventional wheat crops at low soil P fertility levels was concurrent with higher levels of AM
root colonization. The AM fungal communities of soils were simpler than expected. Some 122
phylotypes were found, but only ten of these accounted for over half of the AM fungal DNA
sequences encountered. The main drivers of AM fungal diversity varied with the species of AM
fungi. Among all the variables considered, soil organic matter level and soil texture were most
often significantly correlated with the relative abundance of the different AM fungi. The research
results suggest the possibility of using simple regression models to estimate the quality of soil
AM fungal communities invisible to the naked eye. It appears that national databases on soils
and climate, and soil analyses using PRS™-probe can be used to develop cost effective tools
allowing the management of nutrient efficient wheat production systems based on ecological
principles.
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Keywords
arbuscular mycorrhizal fungi, soil phosphorus supply, soil bioresources, biogeography, wheat phosphorus uptake, wheat phosphorus nutrition
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Part Of
Soils and Crops Workshop