Root morphological response of six peanut cultivars to chromium (VI) toxicity.

We investigated the hypothesis that root morphology plays a crucial role in the variation in chromium (Cr) accumulation among peanut (Arachis hypogaea L.) cultivars, using the relationship between Cr accumulation and morphological characteristics of six peanut cultivars determined under 0, 10, 25, 75, and 100 μmol L-1 Cr(VI) via hydroponic experiment. Significant variations were observed in Cr accumulation and root morphological parameters among peanut cultivars at the five Cr levels. The Cr concentrations in plants exhibited 1.72-, 4.67-, 1.81-, and 2.91-fold variations within cultivars for 10, 25, 75, and 100 μmol L-1 Cr treatments, respectively. Positive correlations were found for total Cr in plants with total root length (RL), root surface area (SA), and root volume (RV). Negative correlations were also observed between the percentages of Cr in shoots and specific root length. These results suggest that root system morphology may partly explain the variation in Cr accumulation among cultivars. Cultivars with greater RL, SA, and RV showed higher capability for Cr accumulation.