Seed Germination and Urban Wastewater Remediation Using Micro-Fe-Modified Montmorillonite

In recent years, it has become increasingly clear that agricultural production must adopt innovative and sustainable strategies to enhance productivity, while reducing environmental harm. Urban wastewater, rich in phosphorus (P), represents a valuable yet underused resource for agriculture, offering an alternative to the continuous addition of synthetic fertilizer input. This research explores a nanotechnology-based solution utilizing a montmorillonite composite enriched with Fe (TechPhos) to enhance germination. XRD, XRF, and N₂ adsorption/desorption isotherms characterized TechPhos. Then, the effects of TechPhos on the germination process of lettuce (Lactuca sativa), soy (Glycine max), and rice (Oryza sativa) after exposure to 0.4 g L^-1 TechPhos were assessed. Seeds in the TechPhos treatment germinated rapidly, reaching 82-100, 73-100, and 57-95% germination for L. sativa, G. max, and O. sativa, respectively. The germination index remained relatively stable in lettuce, while in soy, it peaked at 48 h before gradually decreasing, and in rice, it showed a declining trend. Germination velocity and mean germination time (MGT) followed comparable trends. For L. sativa, the MGT showed a gradual increase in the control and with TechPhos, reaching 5.0 ± 0.0 at 120 h in the control and 4.9 ± 0.1 under the TechPhos treatment. In G. max, the MGT exhibited a similar trend in both conditions, increasing from 0.7 ± 0.1 at 24 h to 5.0 ± 0.0 at 120 h. For O. sativa, the MGT was 1.1 ± 0.3 at 48 and 4.6 ± 0.1 at 120 h in the control compared to 1.4 ± 0.1 at 48 h and 4.8 ± 0.1 at 120 h under the TechPhos treatment. L. sativa showed a 35% increase in root elongation (p < 0.001) and a 37% increase in hypocotyl elongation (p < 0.001) under TechPhos treatment. At the same time, G. max exhibited a smaller but significant increase in root length (p < 0.05). Our findings indicate that TechPhos is not toxic to the three species, enhances germination and root growth of L. sativa and G. max seeds, and allows its use as fertilizer, offering a dual benefit: reducing nutrient pollution and strengthening their potential for agricultural applications.