The Efficacy of Sunn Hemp (Crotalaria juncea) and Fe3O4 Nanoparticles in Controlling Weed Seed Germination

Utilizing nanotechnology for weed management offers a sustainable alternative to synthetic herbicides. This study evaluated the effectiveness of sunn hemp extract (SH), Fe3O4 nanoparticles (NPs), and Fe3O4/sunn hemp NPs in inhibiting the germination of redroot pigweed (Amaranthus retroflexus L.), wild mustard (Sinapis arvensis L.), and lamb’s quarters (Chenopodium album L.) weeds. The structural characteristics of the NPs were analyzed using Scanning electron microscopy (SEM), Scanning X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Vibrating sample magnetometer (VSM), Brunner–Emmet–Teller (BET), and Fourier-transform infrared spectroscopy (FTIR). The optimal Fe3O4 NP concentration for reducing seed germination ranged from 3000 to 3100 mg L−1. Higher concentrations of SH extract (100, 150, and 200 g L−1) effectively inhibited weed seed germination with A. retroflexus displaying the highest sensitivity. The maximal effective concentration (NOECmax) for Fe3O4/sunn hemp NPs was 10 g L−1 for S. arvensis, 150 g L−1 for A. retroflexus, and 200 g L−1 for C. album. Fe3O4/sunn hemp NPs led to a reduction in 1/D50 and an increase in EEC50, indicating a rise in sensitivity to Fe3O4 NPs, particularly in S. arvensis. Variations in species responses to SH, Fe3O4 NPs, and Fe3O4/sunn hemp NPs are likely influenced by genetic, physiological, and ecological factors. Overall, the findings suggest that utilizing Fe3O4/sunn hemp NPs offers an effective strategy for sustainable weed management.