Managing arbuscular mycorrhizal fungi in cropping systems

Abstract

Plencette, C., Clermont-Dauphin, C., Meynard, J. M. and Fortin, J. A. 2005. Managing arbuscular mycorrhizal fungi in cropping systems. Can. J. Plant Sci. 85: 31-40. Market globalization, demographic pressure, and environmental degradation have led us to reconsider many of our current agricultural systems. The heavy use of chemical inputs, including fertilizers and pesticides, has resulted in pollution, decreased biodiversity in intensively-farmed regions, degradation of fragile agro-ecosystems, and prohibitive costs for many farmers. Low input sustainable cropping systems should replace conventional agriculture, but this requires a more comprehensive understanding of the biological interactions within agro-ecosystems. Mycorrhizal fungi appear to be the most important telluric organisms to consider. Mycorrhizae, which result from a symbiosis between these fungi and plant roots, are directly involved in plant mineral nutrition, the control of plant pathogens, and drought tolerance. Most horticultural and crop plants are symbiotic with arbuscular mycorrhizal fungi. Mycorrhizal literature is abundant, showing that stimulation of plant growth can be mainly attributed to improved phosphorous nutrition. Although the mycorrhizal potential of its symbiosis to improve crop production is widely recognized, it is not implemented in agricultural systems. There is an urgent need to improve and widely apply analytical methods to evaluate characteristics such as, relative field mycorrhizal dependency, soil mycorrhizal infectivity, and mycorrhizal receptivity of soil. Decreased use of fertilizers, pesticides, and tillage will favour arbuscular mycorrhizal fungi. However, shifting from one system to a more sustainable one is not easy since all components of the cropping system are closely linked. Different cases, from actual agricultural practices in different countries, are analyzed to highlight situations in which mycorrhizae might or might not play a role in developing more sustainable agriculture. Key words:Cropping systems, mycorrhizae, sustainability, technical itineraries, rotation Plencette, C., Clermont-Dauphin, C., Meynard, J. M. et Fortin, J. A. 2005. Gestion des champignons mycorchiziens a arbuscules dans les systemes de culture. Can. J. Plant Sci. 85: 31-40. La globalisation mondiale du marché, la pression démographique et la dégradation de l'environnement ont, dans plusieurs parties du monde, mené à une réévaluation des systèmes agricoles actuels. Les modifications de l'environnement montrent que l'utilisation des engrais et des pesticides a atteint ses limites : pollution et perte de biodiversité dans les régions d'agriculture intensive, dégradation des systèmes agricoles les plus fragiles, coûts prohibitifs pour les producteurs les plus pauvres. L'agriculture conventionnelle doit s'orienter vers des pratiques plus durables, mais les systèmes de culture durable à faibles intrants ne pourront être viables que par une meilleure connaissance et maîtrise des interactions biologiques dans ces agro-systèmes. Les champign...

Biotic interactions, ecological knowledge and agriculture

“…Most horticultural and crop plants are symbiotic with AMF, but exploration of how to best utilize this relationship in crop management is in its infancy (Plenchette et al 2005;Gosling et al 2006). In general, the beneficial effects of AMF through improved P nutrition are seen at low-to-moderate soil P levels (Lekberg & Koide 2005;Plenchette et al 2005).…”

“…In general, the beneficial effects of AMF through improved P nutrition are seen at low-to-moderate soil P levels (Lekberg & Koide 2005;Plenchette et al 2005). A meta-analysis of 290 published studies found that inoculation with AMF increased root colonization by 29% and that some management practices also increased colonization such as shortened fallow (by 20%) and reduced soil disturbance (by 7%).…”

Mycorrhizal Interactions for Reforestation: Constraints to Dryland Agroforest in Brazil

“…The use of legumes for sustainable agriculture is highlighted by beneficial effects on the ecophysiology, on the biota of the rhizospheric soil, and on associated nonlegumes due to symbioses [63]. It is also known that legumes are generally more mycotrophic than other plants [64] and that they can increase the concentration of AM spores in the soil [65]. Nitrogen fixation in legumes shows that functional diversity should be closely correlated with phylogenetic diversity.…”

“…Although the potential of this symbiosis to improve crop production is widely recognized, it is not implemented in agricultural systems [64].…”

“…Mycorrhizas are generally accepted to be of importance; however, research is not fully integrated with ecology and agronomy [95]. Although the potential of this symbiosis to improve crop production is widely recognized, it is not implemented in agricultural systems [64].…”