Mycorrhizal activity and diversity in a long-term organic Mediterranean agroecosystem

Abstract

In organic agriculture, soil fertility and productivity rely on biological processes carried out by soil microbes, which represent the key elements of agroecosystem functioning. Arbuscular mycorrhizal fungi (AMF), fundamental microorganisms for soil fertility, plant nutrition and health, may play an important role in organic agriculture by compensating for the reduced use of fertilizers and pesticides. Though, AMF activity and diversity following conversion from conventional to organic farming are poorly investigated. Here we studied AMF abundance, diversity and activity in short- and long-term organically and conventionally managed Mediterranean arable agroecosystems. Our results show that both AMF population activity, as assessed by the mycorrhizal inoculum potential (MIP) assay, the percentage of colonized root length of the field crop (maize) and glomalin-related soil protein (GRSP) content were higher in organically managed fields and increased with time since transition to organic farming. Here, we showed an increase of GRSP content in arable organic systems and a strong correlation with soil MIP values. The analysis of AMF spores showed differences among communities of the three microagroecosystems in terms of species richness and composition as suggested by a multivariate analysis. All our data indicate that AMF respond positively to the transition to organic farming by a progressive enhancement of their activity that seems independent from the species richness of the AMF communities. Our study contributes to the understanding of the effects of agricultural managements on AMF, which represent a promising tool for the implementation of sustainable agriculture

Arbuscular mycorrhizal fungal activity responses to winter cover crops in a sunflower and maize cropping system

“…We found positive correlations between this glomalin fraction and the three AMF variables in maize and to a lesser extent in sunflower. Our results are in line with Bedini et al (2013), who detected a strong correlation of GRSP with soil mycorrhizal inoculum potential determined in a bioassay, a moderate correlation with root colonization and no correlation with spore number. On the other hand, and in agreement with our results, a correlation between EE-GRSP and AMF spore density was found by Bedini et al (2007) and Bai et al (2009).…”

Population and Diversity of Arbuscular Mycorrhiza Fungi in the Rhizosphere of Kasetsart Cassava Clone Grown on Two Different Locations

“…The maximum number of spores can be found in soils containing organic matter 1% up to 2%, whereas in , where soils containing organic matter <0.5% the number of spores is very low (Anas 1997). The studies of Oehl et al (2005) and Bedini et al (2013) also reported that the highest number of AMF spores was obtained from soil with high organic matter content. The results of their studies are in line with the results of current study.…”

“…However, the population level and composition of the AMF types vary considerably. The population of AMF can be affected by biotic factors such as plant species and abiotic factors such as temperature, soil pH, soil moisture, organic matter content, and concentrations of phosphorus, nitrogen and heavy metal (Brundrett and Ashwath 2013;Bedini et al 2013;Omorusi and Ayanru 2011;Lekberg et al 2008).…”

GM Crops, Organic Agriculture and Breeding for Sustainability

“…[38] One of the main arguments used against organic or biological farming is that yields under organic systems are lower than in conventional agriculture; for example, in the case of cereals, 60%-70% of those under conventional management [30]. Although organic farming maintains fertility [39,40] and preserves part of the biodiversity of the cropped land [41], the idea of using 30%-40% more land to produce the same amount of crop biomass is unacceptable [30].…”