Effect of Aluminum Doses and Sources On Roots Morphological Parameters of Upland Rice.

There are doubts about the aluminum (Al³⁺) concentration and source to produce toxicity in nutrient solution experiments with upland rice, in some studies is used aluminum sulfate - AlK(SO₄)₂.12H₂O, on the other hand is used chloride aluminum (AlCl₃.6H₂O). So the aimed of this study was to evaluate the Al³⁺ concentration and source effects in the root morphological parameters (length, surface area, volume and diameter of upland rice plants), in order to define the best Al³⁺ concentration and source to produce toxicity for use in nutrient solution experiments. The experiment was conduct using experimental design in randomized blocks, in factorial design 2x5 with four replications. The treatments were two Al³⁺ source (aluminum sulfate and aluminum chloride) and added five Al³⁺ doses (0; 370; 740; 1.110 and 1.480 μmol L^-1). There was decrease of root length, surface area and volume, when applied Al³⁺. This happened because the root in contact with Al³⁺ there is their growth inhibition. The root diameter increased with Al³⁺ application, it occurred because the root become stunted according of root meristem injury or death and increase the rigidity of the cell wall and their diameter. Furthermore, roots morphological parameters evaluated, as surface area and root volume were lower when using the aluminum chloride when compared with aluminum sulphate, indicating that this can produce higher toxicity to upland rice plants. So, the use of aluminum chloride and the concentration of 1.480 μmol L^-1 Al³⁺ is more efficient in producing toxicity to upland rice plants.