Metabolismo bioquímico e estado nutricional de plantas jovens de paricá sob concentrações de alumínio

Abstract

Schizolobium amazonicum Huber ex Ducke (paricá) is a timber specie with high productivity and high economical and ecological importance, occurs mainly in tropical acid soils with high exchangeable aluminum content. Aluminum toxicity it is one of the main factors limiting the development of plants in acid soils. The aim of this study was to evaluate the effect of different concentrations of Alº?* at height, weight of dry matter, nutritional status and biochemical metabolism paricá plants grown in nutrient solution. The experimental design was a randomized block, with five blocks, where each block contained a plant of each treatment totaling five replications, each plant an experimental unit. The treatments were four aluminum concentrations: 0; 5; 10; 20 and 40 mg L"!, applied to the nutrient solution in the form of aluminum chloride (AlICI3). For analysis in the EDS were used three treatments: 0; 20 and 40 mg L"' Al. The dry weight increased significantly in the roots of plants grown in nutrient solution with AIº*, while the shoot wasreduced. The plants most affected by the toxic effects of aluminum were those containing 20 e 40 mg L" of AI?*. The macro content (N, P, Ca, Mg and K) and micronutrients (Fe, Cu and Mn) were significantly affected by Al**, except Zn. The shoot was the most affected by toxicity, where the content of most nutrients was reduced. The accumulation of macronutrients was higher at the root with the addition of Al in the nutrient solution compared to the shoot. For micronutrients observed similar behavior, except for Fe which showed no significant difference in root and Zn in the shoot. The concentration of nitrate and ammonium in the roots increased in the presence of phytotoxic metal, while the concentration of amino acids, proteins, carbohydrates and starch decreased at doses above 5 mg L"!. Among amino acids which provide resistance to abiotic stress, proline and glycine betaine, only a glycine increased with the addition of Al**, while proline was affected by toxicity and had a drop in concentration in the presence of Al**. The aluminum tended to accumulate in the epidermis of the roots (43% of total), decreasing as the proximity to the vascular cylinder.