Tolerância da erva-mate (Ilex paraguariensis St. Hil.) ao alumínio

• Autor(a) principal: Benedetti, Eliziane Luiza
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1629
• topic: Toxidez de alumínio; Acidez do solo; Ácidos orgânicos; Aluminum toxicity; Soil acidity; Organic acids; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

Mate (Ilex paraguariensis) grows naturally in soils with high content of aluminum. Aluminum is toxic to most plant species, impairing their growth. However, there are species which grow better in presence of relatively high aluminum content, what can be considered an indication of tolerance to this element. Mechanisms of tolerance to aluminum may vary among plant genotypes and phenols are suggested as being involved in this process in mate. Similarly, boron nutrition may take part in the process as it influences phenol synthesis by the plants. Therefore, this study aimed to evaluate differential tolerance of mate clones and the involvement of boron and phenolic compounds in the tolerance of mate seedlings to aluminum. Two trials were carried out in nutrient solution under greenhouse conditions. In the first, seedling of three mate clones (F02, A35 and A07) were grown in solutions containing 0, 100, 500, 1000 and 2000 µmol/L Al during 50 days. Increasing Al in the solution, to a certain concentration, enhanced mate shoot and root growth, photosynthesis rate and stomata conductance but decreased phosphorus and calcium foliar concentrations. The response pattern and intensity varied with clone. Plants accumulated aluminum in the roots avoiding its transport to the shoot, which could be a strategy to tolerate high aluminum concentration in the growing solution. This study showed that root length and dry matter are good indicators of mate aluminum tolerance. In the second study, mate seedlings were submitted to a factorial combination (presence or absence) of aluminum and boron in the nutrient solution for 80 days. Boron was supplied at the concentration of 92.6 µmol/L and aluminum at the concentration of 1000 µmol/L. There were no significant changes in the nutritional status of the plants, but a synergetic effect of boron and aluminum was observed on seedling growth. Aluminum favored the increase of gallocatechin, epigallocatechin gallate and chlorogenic acid concentrations in the leaves and it is suggested that these compounds may be involved in mate tolerance to aluminum.