Enhancing physio-biochemical characteristics in okra genotypes through seed priming with biogenic zinc oxide nanoparticles synthesized from halophytic plant extracts.

Poor seedling germination and growth can result in large financial losses for farmers, thus, there is an urgent need for sustainable agricultural techniques to enhance seed germination and early growth. As an outcome, sustainable agriculture-which emphasizes the smart and effective utilization of resources-has gained popularity worldwide. At numerous levels, the field of nanotechnology is capable of significant benefit in achieving sustainable agricultural practices. Zinc oxide nanoparticles (ZnO NPs) have been shown to have biostimulatory properties and serve as effective solutions for addressing environmental and biotic stressors. The purpose of this study, investigating Salvadora persica halophytic leaf extract -synthesized zinc oxide nanoparticles (S-ZnONPs) as nano-priming agents to ensure okra seeds germinated under stress-free conditions. From an application perspective, we examined the effect of seed priming with varying concentrations of S-ZnO NPs (0, 20 and 40 ppm) for 18 and 24 h of soaking. Results indicated that the germination rate of hybrid variety improved with 20 ppm at 18 h, increasing by 58.22%, while mean germination time reduced by 24.62%. An enhancement trend was observed in the shoot, root length, shoot and root fresh weight, shoot and root dry weight of hybrid variety at 20ppm with 18 h priming by 34.2, 84.3, 80.2, 47.4, 50.3, and 36.2%, respectively. However, chlorophyll pigments chl a, chl b, and carotenoids was significantly raised in desi variety by 42.4, 79.31, and 142.29% with 20 ppm at 18 h priming. Hydrogen per oxide decreased up to 87.8% with 40 ppm at 24 h in hybrid variety, while, in desi variety H2O2 was reduced 88.3% with 20 ppm at 24 h. Non enzymatic antioxidant activities such as ascorbic acid, was highly increased 130.6% in hybrid at 24 h priming with 20 ppm dose. Flavonoids raised in same variety by 166.1% with 20 ppm at 18 h. Proline content was increased by 144.5% with 40ppm at 18 h. Moreover, Antioxidant enzymes, superoxide dismutase, peroxidase and catalase were significantly increased in both varieties with both levels of S-ZnO NPs and priming time. This cost-effective and environmentally safe technique to produce nanoparticles of different halophytic plants can maximize resource utilization, supporting sustainable agriculture by minimizing adverse environmental effects without compromising efficiency.

Synthesis of phytostabilized zinc oxide nanoparticles and their effects on physiological and anti-oxidative responses of Zea mays (L.) under chromium stress.

Chromium (Cr) is a hazardous metal that has a significant risk of transfer from soil to edible parts of food crops, including shoot tissues. Reduction of Cr accumulation is required to lower the risk of Cr-exposed in humans and animals feeding on metal-contaminated parts of such plant. Zea mays is a global staple crop irrigated intensively with Cr-contaminated water. Consequently, the objective of this study was to investigate that FI-stabilized ZnO NPs could be used as an eco-friendly and efficient amendment to reduced Cr uptake and toxicity in Zea mays. To investigate the growth parameters, physiological, oxidative stress and biochemical parameters under different Cr-VI concentrations (10.0, 15.0, and 20.0 ppm). Cr exposed Z. mays plants exhibited substantially reduced plant biomass, chlorophyll contents, and altered antioxidant enzyme activity compared to untreated control. The results revealed that foliar application of Fagonia-ZnO-NPs helps eliminate the harmful effects of Cr (VI), which can enter plants through soil pollution. Increased levels of proline, soluble sugars and various antioxidant enzymes reflected this. Mean comparisons showed that Cr stress led to a 33-50% reduction in fresh shoot weight, 73-170% in fresh root weight, 16-34% shoot length, 9.5-129% root length, Chlorophyll contents 20-33% (Chl a), 18-27% (Chl b) and 17-27% (car), 14-33% total soluble sugars, 54-170% proline content, 7-7.5% POD, 0.66-75% CAT and 32-77% APX enzyme activities compared to untreated plants. Application of FI-stabilized ZnO NPs led to an increase 21-77% in fresh shoot weight, 22-45%, fresh root weight, 3-35% shoot length, 24-154% root length, Chlorophyll contents 39-60% (Chl a), 15-79% (Chl b) and 28-82% (car), 19-52% total soluble sugars, 21-55% proline content, 14-43% POD, 34-95% CAT and 130-186% APX enzyme activities under 10, 15 and 20 ppm Cr stress respectively, compared to Cr-treated plants. However, the principal component analysis revealed that chlorophyll contents, carotenoid, CAT, APX and length were in the same group and showed a positive correlation. These data collectively suggest that phytostabilized zinc oxide NPs may be an eco-friendly solution to mitigate Cr toxicity in agricultural soils and crop plants.