Facundo Rivera-Becerril

Impacts of manganese mining activity on the environment: interactions among soil, plants, and arbuscular mycorrhiza.

The mining district of Molango in the Hidalgo State, Mexico, possesses one of the largest deposits of manganese (Mn) ore in the world. This research assessed the impacts of Mn mining activity on the environment, particularly the interactions among soil, plants, and arbuscular mycorrhiza (AM) at a location under the influence of an open Mn mine. Soils and plants from three sites (soil under maize, soil under native vegetation, and mine wastes with some vegetation) were analyzed. Available Mn in both soil types and mine wastes did not reach toxic levels. Samples of the two soil types were similar regarding physical, chemical, and biological properties; mine wastes were characterized by poor physical structure, nutrient deficiencies, and a decreased number of arbuscular mycorrhizal fungi (AMF) spores. Tissues of six plant species accumulated Mn at normal levels. AM was absent in the five plant species (Ambrosia psilostachya, Chenopodium ambrosoides, Cynodon dactylon, Polygonum hydropiperoides, and Wigandia urens) established in mine wastes, which was consistent with the significantly lower number of AMF spores compared with both soil types. A. psilostachya (native vegetation) and Zea mays showed mycorrhizal colonization in their root systems; in the former, AM significantly decreased Mn uptake. The following was concluded: (1) soils, mine wastes, and plant tissues did not accumulate Mn at toxic levels; (2) despite its poor physical structure and nutrient deficiencies, the mine waste site was colonized by at least five plant species; (3) plants growing in both soil types interacted with AMF; and (4) mycorrhizal colonization of A. psilostachya influenced low uptake of Mn by plant tissues.

Inoculación con consorcios nativos de hongos de micorriza arbuscular en Agave angustifolia Haw

The aim of this work was to determine the functional compatibility of native inoculums of arbuscular mycorrhizal fungi (AMF) in Agave angustifolia, using parameter of growing and nutrition as indicators. In the greenhouse from the Soil Laboratory Unit CIIDIR in Oaxaca, during 2009, an experiment was conducted a two-factor with a combine array with four replications and distribution of treatments in randomized complete blocks. The experimental factors and their levels were: factor A: maguey seedlings propagated by vegetative tillers (HI) and by floral bulbils (BU), factor B, six native inoculums of AMF consortia from the district of Tlacolula, Oaxaca (CN1 to CN6 ), positive control Glomus intraradices (GI) and uninoculated absolute control (CON). The response variables were: plant height, leaf area per plant, root length and distribution and biomass at harvest (fresh and dry weight of leaves, stem and roots), concentration and content of N and P in leaves and mycorrhizal colonization. In HI was recorded the highest degree of compatibility with the inoculum CN2. BU recorded compatibility with inoculums CN4, CN6 and GI. The plants that were inoculated with CN2 recorded the highest values in compatibility indicator variables, followed closely by those receiving the inoculum