Microbial Inoculants and Sugarcane Residues Promote Mucuna pruriens Development in Tebuthiuron-Affected Soil: Biological Amendments Support Plant Growth in Polluted Substrate

This study evaluated the individual and combined effects of different bio-inputs—traditional filter cake, filter cake composted with ash, and a microbial inoculant—on the growth and physiological performance of Mucuna pruriens cultivated in soil contaminated with the herbicide tebuthiuron. The experiment followed a completely randomized design with twelve treatments and five evaluation periods (7, 21, 35, 49, and 70 days after sowing). Morphophysiological variables such as plant height, root length, dry biomass, and chlorophyll content were assessed. The results showed that the addition of traditional filter cake promoted significant growth in tebuthiuron-contaminated soil, while, in uncontaminated conditions, both organic residues and the microbial inoculant enhanced plant development, particularly at later stages. Initial phytotoxicity was observed in treatments with organic residues (up to 67% of samples before 35 days), but these effects decreased over time. The microbial inoculant performed better in the absence of organic amendments, suggesting possible antagonistic interactions. Tebuthiuron reduced chlorophyll content by inhibiting photosystem II, but this effect was mitigated by the addition of filter cake. Overall, the findings highlight the potential of integrating Mucuna pruriens cultivation with organic residues and microbial inoculants as an effective phytomanagement strategy for tebuthiuron-affected soils. This approach provides a sustainable model for improving soil health, supporting legume-based rehabilitation, and advancing biological alternatives to conventional remediation practices.