Abstract

Crambe is a potential oilseed plant, which has been suggested for cultivation as a cover crop in the Brazilian Savanna where acidic soils predominate. Understanding of its performance in those conditions is essential. Thus, the objective of this study was to characterize the morphological and physiological changes in crambe plants when subjected to Al exposure at different dose levels. Plants were allocated to a nutrient solution with Al treatments at concentrations of 0.0, 0.1, 0.2, 0.3 and 0.4 mmol L^-1. The following parameters were determined: length of root (LR) and shoot (LS), dry mass of roots (RDM) and shoots (SDM), Al uptake in plant tissues, leaf area (LA), absolute growth rate (AGR), grain yield (GY), net CO₂ assimilation rate (A), stomatal conductance (g_s), transpiration rate (E) and chlorophyll α fluorescence. The experimental design was completely randomized, consisting of five treatments with four replications. Regression analyses of growth parameters and mean comparative tests of physiological traits were performed. Roots concentrated approximately 40-fold more Al than shoots. There was a linear reduction in LS and LR with increasing doses of Al. For RDM, SDM, LA, AGR and GY, the reductions were similar and were better explained by quadratic models. Al damaged the photosynthetic apparatus of crambe plants, demonstrated by a significant reduction in the values of Fv/Fm (estimation of photosynthetic efficiency), A, gs and E, compared to the control. Al negatively affected growth parameters as well as the photosynthetic response of crambe plants, resulting in a substantial decrease in its grain yield.

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