This study sought to identify and characterize Heterorhabditis indica, its symbiotic bacteria, and Meloidogyne incognita, while assessing the nematicidal efficacy of silver nanoparticles synthesized using Photorhabdus luminescens supernatant (PsAgNPs). Molecular and phylogenetic analyses verified the identity of H. indica and M. incognita, revealing no nucleotide discrepancies from previously characterized species. P. luminescens exhibited entomopathogenic properties, and its supernatant enabled the biosynthesis of PsAgNPs under optimal conditions (26 +/- 2 degrees C, pH 9). Characterization of PsAgNPs indicated a UV-visible absorption peak at 430 nm, a crystalline structure with an average particle size of 22.38 nm (XRD), and a zeta potential of -41.7 +/- 0.74 mV, signifying high stability. FTIR analysis suggested that proteins and polysaccharides contributed to nanoparticle stabilization, while EDX confirmed 70.01% silver purity. SEM and TEM analyses demonstrated spherical nanoparticles with sizes ranging from 15.5 to 40 nm. In vitro bioassays revealed that PsAgNPs significantly suppressed M. incognita egg hatchability and juvenile mortality in a dose-dependent manner. At 200 mu g/mL, PsAgNPs reduced egg hatchability to 24.6% and caused 100% juvenile mortality. In contrast, the bacterial supernatant alone exhibited a lower efficacy. The LC50 values for PsAgNPs were 13.1 mu g/mL and 14 mu g/mL at 12 and 24 h, respectively, indicating potent nematicidal activity. In vivo pot experiments on tomato plants demonstrated a pronounced reduction in gall formation (95.3%) and egg mass production (93.1%) at 100 mu g/mL PsAgNPs. Soil nematode populations were significantly reduced, with the lowest density recorded in PsAgNP-treated plants (53.3 juveniles). Additionally, PsAgNPs substantially enhanced plant growth, increasing fresh and dry shoot and root biomass by 61.2% and 64.6%, respectively, compared to controls. Histopathological analysis corroborated reduced tissue damage in PsAgNP-treated plants. These results underscore the potential of PsAgNPs as a viable biocontrol agent for managing M. incognita, presenting an environmentally sustainable alternative to traditional nematicides.

Nanotechnology offers creative and effective solutions for addressing various environmental issues, such as heavy metals (HM). The rapidly increasing HM concentrations in agricultural land have drawn considerable attention. Nanoparticles (NPs) have special physiochemical features that help reduce stress. This study assessed the viability of applying CeO2NPs 2 NPs and FeONPs to rice plants at a concentration of 25 mg/L to effectively remove the detrimental effects of lead (Pb) by using various concentrations (100 and 200 ppm) on plant development and growth. To achieve the desired concentrations, a Pb solution was prepared by dissolving lead nitrate in distilled water and added to the soil. Interestingly, the application of CeO2NPs 2 NPs and FeONPs resulted in a notable increase in plant growth, biomass, gas exchange characteristics, antioxidant enzymatic activity (SOD, POD, APX, and CAT), their gene expressions, as well as other antioxidants (phenols, prolines, amino acids, flavonoids, anthocyanins, and ascorbic acids) while simultaneously reducing oxidative stress (MDA, H2O2, 2 O 2 , and electrolyte leakage) and Pb uptake in rice. Conversely, Pb elevation in the soil increased oxidative damage and organic acid exudation pattern in the rice. At 200 ppm, a significant rise in Pb content (416.67 % and 380 %) was found in the roots and leaves of rice plants. According to our findings, rice growth can be bio-stimulated by CeO2NPs 2 NPs and FeONPs. Subsequent investigations should focus on the persistent ecological consequences and molecular mechanisms associated with the application of cerium oxide and iron oxide nanoparticles in agriculture to reduce Pb-induced oxidative stress. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.