Assessing the Infectivity of Commercial Mycorrhizal Inoculants in Plant Nursery Conditions

Abstract

The infectivity of ten commercial mycorrhizal inoculants was examined in nursery conditions. Corn plants were grown in a soil-based medium and in two different soilless substrates, a potting mix prepared with redwood bark, pine sawdust, calcined clay and sand, and the commercial Sunshine #5 mix, mainly composed of Canadian sphagnum peat moss. The percentage of mycorrhizal colonization obtained with the different mycorrhizal inoculants ranged from 0 to 50%. This variation might reflect the presence or absence of viable propagules, the difference in the recommended rates applied as well as the difference in the content and type of infective propagules of each product. However, the infectivity of each mycorrhizal inoculant was also influenced by the growing media. Two products promoted higher values of mycorrhizal colonization in the Sunshine mix, three in the nursery mix and one in the soil-based medium. Mycorrhizal colonization did not enhance plant growth. Only the plants inoculated with the products that did not promote mycorrhizal colonization increased their growth relative to the non-inoculated controls, suggesting the presence of other growth promoters in the inoculum products. Based on these results, nurseries should conduct preliminary tests to determine which inoculants will perform in their potting mixes to assure the best fit of inoculum with their particular conditions.

Arbuscular mycorrhizal association in coffee

“…However, commercially available mycorrhizal inoculum normally leads to an extremely high density of AMF propagules per volume of soil (Costa et al 2003), thereby enabling a rapid mycorrhizal establishment of coffee seedlings and making AMF inoculation a highly recommended practice at the nursery stage. Therefore, AM fungi are gaining popularity as biofertilizers and biocontrol agents (Sylvia 1999) and the industry of mycorrhizal inoculum production is expanding around the world (Corkidi et al 2004; Todd 2004).…”

‘Glomus intraradices DAOM197198’, a model fungus in arbuscular mycorrhiza research, is not Glomus intraradices

“…for a genome sequencing project; Martin et al ., 2008) and to demonstrate transient genetic transformation (Helber & Requena, 2008). It also is a component of some commercial plant growth‐enhancing products (Corkidi et al ., 2004; http://www.pro-mixbas.com).…”

Genetic diversity of the arbuscular mycorrhizal fungus Glomus intraradices as determined by mitochondrial large subunit rRNA gene sequences is considerably higher than previously expected

“…It is widespread geographically and tolerates a wide range of habitats (Öpik et al ., 2006). It is also compatible with all culturing systems currently in use, from glasshouse pots to root‐organ cultures (Jansa et al ., 2002a), and thus is one of the most common fungal components in commercial inocula (Corkidi et al ., 2004). Not surprisingly, therefore, it was chosen as the model AMF species for genome sequencing (Martin et al ., 2004).…”