ALUMINUM TOXICITY IN ROOTS OF LEGUME SEEDLINGS ASSESSED BY TOPOLOGICAL ANALYSIS

Abstract

abstract: The effect of the aluminum in root has been evaluated by linear and weight measurements, but remains to be understood about the influence of this element on branching configuration of the root system. This study had the objective to assess the aluminum toxicity in roots of 21-day-old seedlings of three forage legumes, Adesmia latifolia, Trifolium repens and T. pratense (Fabaceae), by topological analysis. The legumes were grown in Oxisol treated or not with dolomite lime, which resulted in two Al saturation and pH: (a) Al= 0 %, pH= 6.2; (b) Al= 16 %, pH= 4.8. Number of first-order roots, external links (magnitude), total links in the longest unique path (altitude), total links in the primary root (altitude of primary root), total exterior path length, total links, internal links, branching points, and proportion of branching in primary root were determined. The topological variables were significantly reduced by Al, regardless to the legumes. The altitude-slope on magnitude showed that there was a more randomized branching configuration in seedlings grown in acid soil. A. latifolia was the most plastic species, with reducing of the slopes from 0.9758 (Al-absence) to 0.6858 (Al-presence), showing herringbone and randomized branching, respectively.