Tolerance to arsenic in Alnus acuminata (Aliso), during the germination and early development Remove selected

• Ano de defesa: 2018
• Autor(a) principal: Ramos Montaño, Carolina
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Alnus acuminata - Desenvolvimento - Efeito dos metais pesados; Germinação; Solo - Teor de arsênio; Carvão - Minas e mineração; Ecofisiologia Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/27564

In Colombia, coal mining has become one of the most frequent economic activities, especially in the Andean region in the department of Boyacá. Currently it is unknown if there is an increase in the concentrations of heavy metals and metalloids in the soil, and the owners of the mines are requested by the government to reforest the post-mining soils, without any species specifically recommended for it. The present investigation addressed the problem of coal mining with two main objectives: (1) To establish if coal mining is associated with high amounts of heavy metals or metalloid arsenic, and find some tree species that was distributed in the proximity of the coal tailings where trace elements are concentrated and (2) To deep in the study of that species to determine if it has any germination tolerance and if it has potential to be used in reforestation plans in post-mining soils. In a first study carried out in the municipality of Samacá (Boyacá-Colombia), transects of 50 m were assembled from the mining tailings to the most conserved area of vegetation, to observe how the diversity and composition changes along the distance. In each of four sampling points, the concentration of aluminum, arsenic, copper, iron, manganese, nickel, lead and zinc were determined. As a result, it was found that, with the exception of arsenic, none of the trace analyzed elements are found in concentrations of toxicological risk, but the diversity changes considerably from the coal source to the exterior; some species would be considered as intolerant because they are present only in the most distant zone. The only tree species found in the closest zone to the coal wastes was Alnus acuminata, a species native from the Neotropic and commonly known as alder. In a second study, the germination characteristics of A. acuminata were evaluated to establish the best conditions that maximize its germination. The results showed that seeds of A. acuminata can be conserved for months at temperatures below 5°C. A pretreatment of cold stratification during 48 hours improves the germination in presence of light and the best conditions for germination were sowing on germitest paper, alternate temperatures 20-30 °C with 12 hours of photoperiod. Finally, in a third study, the effect of arsenic on the germination and early development of A. acuminata with and without a germination pretreatment of stratification was determined. The results of this last study showed that stratification, applied as a cold preimbibition at 3 °C for 48 hours, increases germination by 50% and improves early development, accelerating the emission of the first true leaf. This effect means that even the germinants that come from arsenic treatments have an optimal growth without significant differences with the controls, up to the age of 70 days. With the height of the seedlings was calculated the vigor index of the seeds, which was basically increased in more than 50% in relation to the seeds that had not had a cold pretreatment. Similar results were found with the index of tolerance to arsenic. The general conclusion of this doctoral research is that A. acuminata presents germinative tolerance to arsenic, provided that its seeds receive a pre-treatment of cold imbibition, and this discovery should be used to evaluate the implementation of A. acuminata in plans for recovering of soils affected by coal mining in Colombia.