High aluminum concentration and initial establishment of Handroanthus impetiginosus: clues about an Al non-resistant species in Brazilian Cerrado

Abstract

Cerrado soils are acidic and nutrient-poor, with high content of solubilized Al3+. Plants growing in these conditions may display adaptations to cope with high aluminum concentrations especially during early developmental stages. We investigated leaf nutritional status, and photosynthetic and growth characteristics during the initial establishment of Handroanthus impetiginosus (Mart. Ex Dc.) Mattos, a secondary tree species distributed in the Brazilian Cerrado. Our goal was to understand leaf-level traits related to different aluminum concentrations. H. impetiginosus plants were cultivated in four different aluminum sulfate concentrations: 0, 1, 2, and 4 mM Al, for 40 days. We performed analyses of growth, leaf gas exchange, chloroplast pigment content, and leaf mineral nutrients. We observed a linear increase of Al leaf content as a function of Al concentration in the nutrient solution. Plants grown in 1 mM Al showed a remarkable increase of K leaf content, net photosynthesis, stomatal conductance, and transpiration, while in 4 mM Al there were reductions of N, P, and K contents, gas exchange characteristics, and height. H. impetiginosus did not have mechanisms of avoidance, compartmentalization, or resistance to high Al concentrations. Indeed, this species showed a hormetic response, with low Al concentrations stimulating and high Al concentrations inhibiting plant responses.