Combined Effects of Seaweed Extract and Selenium Nanoparticles on Mitigation of Cadmium and Chromium Stress in Fennel (Foeniculum vulgare Mill.)

Heavy metal contamination by cadmium (Cd) and chromium (Cr) threatens fennel productivity and seed safety through oxidative damage and metal accumulation. This study tested whether combined foliar application of seaweed extract (SWE) and selenium nanoparticles (SeNPs) provides enhanced protection against Cd- and Cr-stress in fennel. For this purpose, a greenhouse factorial experiment was conducted using a randomized complete block design (RCBD) with three replicates. Treatments included three soil metal levels (control, ۲۰ mg Cd kg-۱, and ۱۰۰ mg Cr kg-۱) and four foliar treatments (control, SWE at ۱ mL L-۱, SeNPs at ۲۰ mg L-۱, and SWE + SeNPs). Electrolyte leakage (EL), proline, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), seed Cd/Cr concentrations, seed yield, and biological yield were measured. Results showed that Cd and Cr stress increased membrane and oxidative injury compared with the non-contaminated control, as reflected by higher EL, MDA, CAT, and SOD, and they reduced seed and biological yields. Foliar SeNPs and SWE improved stress tolerance by lowering oxidative damage indices and improving productivity, with SWE+SeNPs treatment showing greater improvements than individual applications. SWE+SeNPs decreased MDA by ۲۷.۸% (Cd) and ۲۲.۷% (Cr), reduced CAT by ۳۲.۸% (Cd) and ۲۸.۳% (Cr), and reduced SOD by ۲۵.۹% (Cd) and ۳۰.۳% (Cr) relative to stressed controls, indicating alleviation of oxidative pressure. The combined treatment also produced the greatest improvement in seed safety by lowering seed Cd by ۶۳.۵% and seed Cr by ۴۱.۱% relative to the foliar control. These biochemical improvements translated into higher productivity, with SWE+SeNPs increasing seed yield by ۲۱.۶% relative to the foliar control and improving biological yield under both Cd and Cr stress. In conclusion, SWE+SeNPs foliar strategy most effectively mitigated Cd/Cr toxicity by reducing oxidative damage, lowering metal transfer to seeds, and improving yield, supporting its potential use for safer fennel production in contaminated soils.

کلیدواژه ها:

Fennel ، Heavy metals ، Seaweed extract ، Seed yield ، Selenium nanoparticles