Abstract

COVACEVICH, F  and  ECHEVERRIA, HE. Indicators to select efficient arbuscular mycorrhizal fungi inocula in moderately acidic soils. Cienc. suelo [online]. 2010, vol.28, n.1, pp.9-22. ISSN 1850-2067.

The propagules of arbuscular mycorrhizal fungi (AMF) in soils are sometimes insufficient in number or efficiency to increase the growth of host plants. That situation could be resolved by inoculating the soils with indigenous or nonin-digenous AMF. However, it must take into account that soils may differ in their receptivity to the introduced AMF. The aim of this work was to select parameters as indicators of the presence, activity and benefit of plant-symbiotic non-indigenous AMF which can be used as inoculants in moderately acidic soils. We evaluated how inoculation with AMF affected mycorrhizal colonization and growth parameters of model onion plants grown in two moderately acid soils of different origin (Argentina and France). Inoculation with Glomus claroideum and Acaulospora longula in the Argentinean soil produced the highest AMF colonization of roots, total alkaline phosphatase activity (ALP) and highest mycorrhizal response (MR). In the soil from France, inoculation with A. longula produced the highest amount of mycorrhizal roots and plant growth. Inoculation with Scutellospora pellucida produced an appropriate MR in the Argentinean soil but no significant MR was detected in the soil from France. G. clarum showed a high capacity to colonize roots but low efficiency for MR. Inoculation with A. laevins produced the lowest levels of colonization and MR in both soils. Direct and multivariate analysis of the tested parameters showed that the accumulation of dry shoot matter and fresh root matter combined with mycorrhizal colonization (both total and with ALP activity) is adequate for the rapid identification of potentially efficient strains for introduction into the tested soils. The ALP efficiently showed tested AMF activities and good correlation with plant growth responses. Although root growth combined with mycorrhizal colonization could be a useful parameter, it must be taken into consideration that it is not easy under field conditions to quantify total root weight per plant. Plant height may in some cases be a useful parameter.

Keywords : Mycorrhiza; Alkaline phosphatase activity; Mycorrhizal responsiveness.

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