Commercial Mycorrhizal Inoculants Research Articles

Effects of Native Plant Species, Mycorrhizal Inoculum, and Mulch on Restoration of Reservoir Sediment Following Dam Removal, Elwha River, Olympic Peninsula, Washington

As dams across the country continue to age, successful restoration of dewatered reservoirs remains a critical factor in decisions regarding dam removal. Freshly exposed reservoir sediment may not support rapid reestablishment of native plant species due to poor fertility or absence of arbuscular mycorrhizal fungi propagules. This field study evaluated treatment effects involving combinations of native plants, mycorrhizal inoculum, and mulch on restoration of dewatered reservoir sediment over 20 months. Most plants, even those uninoculated, became mycorrhizal. In all treatments, sediment pH decreased, as did nitrogen and organic matter, compared to original reservoir sediment, while aggregate stability doubled from original anaerobic sediment. Revegetated plots with mulch had significantly greater vegetation cover and more native volunteer species compared to plots without mulch. The planted mulch treatment also decreased plot runoff tenfold, reducing erosion to the same degree. Indicators suggest that the primary benefit of mulch resulted in increased moisture retention making the planted mulch treatment most successful for restoration of reservoir sediment due to extensive native plant growth, improved soil characteristics, and reduced runoff and erosion compared to nonmulched plots. While results from this plot‐scale study suggest commercial mycorrhizal inoculum is unnecessary since natural inoculum sources sufficiently colonized plants, reservoir‐scale restoration may require creation of additional source areas to encourage rapid reestablishment of native plants and mycorrhizal fungi.

Effect of Arbucula Myrrhizal Fungi on an Ecological Crop of Chili Peppers (Capsicum annuum L.)

Mapuche farmers in southern Chile have been cultivating local ecotypes of chili pepper (Capsicum annuum L.), called locally Cacho de cabra, for many decades. It is used to make merken, a condiment that is consumed locally and exported. This vegetable requires a nursery stage and can obtain nutritional benefits from symbiotic associations such as mycorrhizal fungi, achieving a better adaptation to transplanting. Arbuscular mycorrhizal fungi (AMF) are obligate biotrophes appearing in abundance in agroecosystems with conservation management. The aim of this study was to compare effectiveness of two AMF, a commercial mycorrhizal inoculant (IC, Glomus intraradices) and another native (IN, Glomus claroideum) with a control without inoculation (-I) on the production and quality of Cacho de cabra. At 45 days after sowing (DAS) transplanting was carried out and at 90 and 216 DAS fruit quality, fungal and edaphic parameters were evaluated. The harvest was at four stages. With IN inoculation plants and with greater foliar area were obtained. Also, precocity of fruit production was observed. The harvest started 49 days earlier and fresh weight was 177% higher than that of the control. Root colonization was low, showing significant differences between IN and IC, while a large number of spores was produced in the substrate. It was concluded that inoculation with native fungi decreased transplanting stress thus accelerating the maturation stage of plants and resulting in higher and better yield quality.

Effectiveness of Commercial Mycorrhizal Inoculants on the Growth of Liquidambar styraciflua in Plant Nursery Conditions

Abstract The effectiveness of several commercial mycorrhizal inoculants on the growth and development of Liquidambar styraciflua (sweetgum) was evaluated. Plants were grown in a nursery potting mix and were inoculated with the mycorrhizal products at the manufacturer's recommended rate. The growth response of mycorrhizal and nonmycorrhizal plants was analyzed at two harvests (8 and 14 weeks after transplanting). Significant differences were found in the growth of L. styraciflua to mycorrhizal colonization with the different commercial products. Fourteen weeks after transplanting, inoculation with products 1 (Earth Roots), 2 (MycoApply endo), and 3 (VAM 80) enhanced the growth of sweetgum relative to the nonmycorrhizal plants. However, plants inoculated with products 2 and 3 had greater leaf area, dry mass and relative growth rates than those inoculated with product 1. Plants of L. styraciflua inoculated with product 4 were less responsive to mycorrhizal colonization and only increased their leaf area relative to the non-inoculated controls. Testing both the infectivity and effectiveness of mycorrhizal fungi is recommended for the successful application of mycorrhizal technology in horticultural practices.

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.

Effects of Media and Mycorrhizal Inoculants on Osha (Ligusticum porteri) Rooting

Osha (Ligusticum porteri) is a Rocky Mountain native used as a medicinal herb. Studies are underway to commercially propagate and produce the plant. In an attempt to increase rooting success of crown cuttings taken from osha, five different media were used in conjunction with three commercial mycorrhizal inoculants and a control. Field soil and a pre-mixed commercial product were tested in combinations of 100/0, 75/25, 50/50, 25/75, and 0/100 percent by volume. Each of three commercially-available mycorrhyzal inoculants were tested with each media. Crown cuttings of osha were taken and stuck on 29 Aug. 2003 and were placed on a greenhouse mist bench. Data were taken on days to rooting. Results showed no differences among the media or the inoculants and no interactions were present. There was no benefit in decreased days to rooting with additions of mycorrhizae. There were no responses to different media.

Weaning performance of potato microplants following bacterization and mycorrhization

Commercial mycorrhizal inoculants andPseudomonas fluorescens isolates CHAO and IP10 have been shown to promote microplant growth during and after weaning. The fluorescent pseudomonads also protected against the soil-borne potato pathogenRhizoctonia solani. The potential benefits of inoculation in vitro with mycorrhizal fungi and helper/biocontrol bacteria are discussed.