Arbuscular mycorrhiza in a sustainable world
Sustainable cropping systems will be nutrient efficient and support the capacity of the soil resource. The management of P, a finite resource, appears as a particular challenge. The arbuscular mycorrhizal (AM) fungi will be solicited, as they contribute importantly to soil physical quality and mobilization of nutrients, in particular P.
The AM hyphal networks enmesh the soil matrix providing structural stability and improving water infiltration. These hyphal networks are also an exclusive source of plant available nutrients on which crops get connected soon after germination.
The AM symbiosis particularly improves the efficiency of P use by crops, as the AM hyphal networks extract and mobilize nutrients from mineral and organic substances of soils and act as a pipeline for their rapid translocation to roots. Tight cycling of N and P is one characteristic of nutrient efficient soil-plant systems that is promoted by AM hyphal networks and permits good crop yield on soils with low fertility, thus, reducing environmental losses. Effective transformation of nutrients into yield is another component of nutrient use efficiency that is enhanced by AM fungi. The AM symbiosis is well known to increase plant tolerance to disease and drought stress, thus, maximizing yield at a given level of soil fertility.
Reducing crop dependence on nutrient inputs through the creation of highly effective AM symbioses in crops is a step towards sustainability. The effectiveness of crops AM symbiosis can be improved by the adoption of practices favouring their formation, for example, reduced tillage, reduced frequency of summer fallow, and inoculation with highly effective AM fungal isolates. The use of certain rotations and innocuous pesticides would also strengthen the AM symbiosis of crop plants. Plants have a large influence on their biological environment in part through the production of bioactive phytochemicals. The selection of crop genotypes with improved compatibility with the AM fungi naturally occurring in cultivated fields appears as an ecological approach to the sustainability of crop production. Alternatively, the identification and use of phytochemicals in bioproducts may have direct applications in sustainable crop production, or at least, in AM fungal inoculants production.
Oral presentation at Plant Canada Conference. Saint Mary's University, Halifax, NS. July 17-21, 2011
Author Locations and Affiliations
(1) Semiarid Prairie Agricultural Research Centre AAFC, Swift Current, Saskatchewan, Canada, S9H 3X2
(2) Instituto de Ecologia y Sistematica, Carretera de Varona Km 3 1 / 2, Capdevila, Boyeros, Habana, Cuba
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Posted May 2012