Growth Responses and Phytoremediation Potential of Species of the Genus Crotalaria L. in Ni-Contaminated Soil

When present in excess in the environment, nickel (Ni) can bioaccumulate along the food chain, and become toxic to plants and animals. Phytoremediation represents a sustainable alternative, using plants for soil decontamination. This study aimed to evaluate the growth and phytoremediation potential of four Crotalaria species, cultivated in Ni-contaminated soil. The study was conducted in a greenhouse, under a randomized block design, and a 4 × 5 factorial scheme, containing four species (C. juncea, C. spectabilis, C. breviflora, and C. ochroleuca) and five Ni treatments (0, 35, 70, 140, and 280 mg kg−1). When Ni concentration reached 70 mg kg−1, shoot dry mass decreased by approximately 52% in C. juncea, 53% in C. ochroleuca, 81% in C. breviflora, and 46% in C. spectabilis, compared to the control. C. juncea, C. ochroleuca, and C. breviflora maintained satisfactory growth at 35 mg kg−1 and, for C. breviflora, this concentration increased root dry mass. All species showed high Ni translocation to the shoot, indicating potential for phytoextraction. The concentrations observed did not reach the threshold commonly used to define hyperaccumulator plants (>1000 mg kg−1 dry mass). However, in C. spectabilis, the highest Ni dose led to an increase in root translocation and reduced shoot translocation. Therefore, Crotalaria species demonstrate potential for Ni phytoremediation, although they differ in strategies regarding growth, accumulation, and Ni mobilization.