Foliar Application of Cu Nanoparticles Modified the Content of Bioactive Compounds in Moringa oleifera Lam

Diversity of copper-containing nanoparticles and their influence on plant growth and development

Copper (Cu) is an important microelement for plants, but in high concentrations it can be toxic. Cu-containing nanoparticles (Cu NPs) are less toxic, their use for plants is safer, more effective and economical than the use of Cu salts. This review presents detailed information on the chemical diversity of Cu NPs and various methods of their synthesis. The mechanisms of the effect of Cu NPs on plants are described in detail, and examples of research in this area are given. The main effects of Cu NPs on plants are reviewed including on their growth and development (organogenesis, mitosis, accumulation of biomass), biochemical processes (intensity of photosynthesis, antioxidant status and intensity of lipid peroxidation processes), gene expression, plant resistance to abiotic and biotic stress factors. The prospects of using Cu NPs as mineral fertilizers are shown by describing their stimulation effects on seed germination, plant growth and development, and on increase of plant resistance to stress factors. The protective effect of Cu NPs is often explained by their antioxidant activity. At the same time, there are a number of studies demonstrating the negative impact of Cu NPs on plant growth, development and the intensity of photosynthesis, depending on their concentration. Cu NPs have a pronounced antibacterial effect on bacterial phytopathogens of cultivated plants, as well as on a number of phytopathogenic fungi and nematodes. Thus, Cu NPs are promising agents for agriculture, while their effect on plants requires careful selection of optimal concentrations and comprehensive studies to avoid a toxic effect.

In vitro analysis of green synthesized CuO nanoparticles using Tanacetum parthenium extract for multifunctional applications

Tanacetum parthenium L. is a popular traditional medicinal plant that the role of presence of particular phytochemical compounds are still unconsidered particularly in the bio-nano researches. Here, for the first time, the green fabrication of CuO NPs using Tanacetum parthenium L. extract was performed and assessed for the antimicrobial, cytotoxicity, and dye degradation activities. Characterization of CuO NPs was done by UV-visible spectra, XRD, FT-IR, TEM, and EDX. The synthesized CuO NPs possess a crystalline nature, a functional group that resembles T. parthenium, with a spherical shape particle with an average size of 28 nm. EDX confirmed CuO NPs formation. The CuO NPs showed excellent antimicrobial activity against tested microorganisms. The cytotoxicity of CuO NPs was demonstrated the concentration-dependent inhibition of the growth against both cancer and normal cell lines. The results exhibited concentration-dependent inhibition of the growth of Hela, A 549, and MCF7 cancer cells (IC₅₀ = 65.0, 57.4, and 71.8 µg/mL, respectively), which were statistically significant comparing control cells (IC₅₀ = 226.1 µg/mL). Furthermore, we observed that CuO NPs-induced programmed cell death in the cancer cells were mediated with the downregulation of Bcl2 and upregulation of bax, caspase-3. CuO NPs were verified to be a superb catalyst as they had excellent activity for the degradation of 99.6%, 98.7%, 96.6%, and 96.6% of Congo red, methylene blue, methylene orange, and rhodamine B as industrial dyes in 3, 6.5, 6.5, and 6.5 min, respectively. Overall, the present study nominates T. parthenium as a proper bio-agent in the biosynthesis of CuO NPs with powerful catalytic and antimicrobial activities as well as a cancer treatment.

Effect of methods application of copper nanoparticles in the growth of avocado plants

The aim of this greenhouse study was to evaluate root irrigation, foliar spray, and stem injection in order to find the best method for the nanofertilization of avocado plants with green synthesized CuNPs. One-year-old avocado plants were supplied four times (every 15 days) with 0.25 and 0.50 mg/ml of CuNPs through the three fertilization methods. Stem growth and new leaf formation were evaluated over time and after 60 days of CuNPs exposure, several plant traits (root growth, fresh and dry biomass, plant water content, cytotoxicity, photosynthetic pigments, and total Cu accumulation in plant tissues) were evaluated for CuNPs improvement. Regarding the control treatment, stem growth and new leaf appearance were increased by 25 % and 85 %, respectively, by the CuNPs supply methods of foliar spray>stem injection>root irrigation, with little significant differences among NPs concentrations. Avocado plants supplied with 0.25 and 0.50 mg/ml CuNPs maintained a hydric balance and cell viability ranged from 91 to 96 % through the three NPs application methods. TEM did not reveal any ultrastructural organelle changes induced by CuNPs in leaf tissues. The concentrations of CuNPs tested were not high enough to exert deleterious effects on the photosynthetic machinery of avocado plants, but photosynthetic efficiency was also found to be improved. The foliar spray method showed improved uptake and translocation of CuNPs, with almost no loss of Cu. In general, the improvement in plant traits indicated that the foliar spray method was the best for nanofertilization of avocado plants with CuNPs.

Nanoparticles potentially mediate salt stress tolerance in plants

In the era of climate change, salt stress is a promising threat to agriculture, limiting crop production via imposing primary effects such as osmotic and ionic, as well as secondary effects such as oxidative stress, perturbance in hormonal homeostasis, and nutrient imbalance. On the other hand, production areas are expanding into the salt affected regions due to excessive pressure for fulfilling food security targets to meet the needs of continuously increasing human population. Accumulating evidences demonstrate that supplementation of nanoparticles to plants can significantly alleviate the injurious effects caused by various harsh conditions including salt stress, and hence, regulate adaptive mechanisms in plants. Various types of NPs and nanofertilizers have shown a promising evidence so far regarding salt stress management. In this review, we recapitulate recent pioneering progress made towards acquiring salt stress tolerance in crop plants utilizing NPs. Finally, future research directions in this domain to explicate the comprehensive roles of nanoparticles in improving salt tolerance in plants are underscored. To ensure social acceptance and safe use of NPs, some conclusive directions have been elaborated in order to achieve sustainable progress in crop production under saline environments.

Responses of Tomato Plants under Saline Stress to Foliar Application of Copper Nanoparticles

The tomato crop has great economic and nutritional importance; however, it can be adversely affected by salt stress. The objective of this research is to quantify the agronomic and biochemical responses of tomato plants developed under salt stress with the foliar application of copper nanoparticles. Four treatments were evaluated: foliar application of copper nanoparticles (250 mg L⁻¹) with or without salt stress (50 mM NaCl), salt stress, and an absolute control. Saline stress caused severe damage to the development of tomato plants; however, the damage was mitigated by the foliar application of copper nanoparticles, which increased performance and improved the Na⁺/K⁺ ratio. The content of Cu increased in the tissues of tomato plants under salinity with the application of Cu nanoparticles, which increased the phenols (16%) in the leaves and the content of vitamin C (80%), glutathione (GSH) (81%), and phenols (7.8%) in the fruit compared with the control. Similarly, the enzyme activity of phenylalanine ammonia lyase (PAL), ascorbate peroxidase (APX), glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) increased in leaf tissue by 104%, 140%, 26%, 8%, and 93%, respectively. Foliar spraying of copper nanoparticles on tomatoes under salinity appears to induce stress tolerance to salinity by stimulating the plant’s antioxidant mechanisms.

The Effect of an Edible Coating with Tomato Oily Extract on the Physicochemical and Antioxidant Properties of Garambullo (Myrtillocactus geometrizans) Fruits

The Myrtillocactus geometrizans (Mart. ex. Pfeiff.) fruit, locally called garambullo, is an important source of bioactive compounds, mainly betalains, polyphenols, and ascorbic acid. However, information on the application of post-harvest technologies that prolong the shelf life of the fruits is still insufficient. The objective of the present research was to evaluate the effect of a gelatin coating incorporating 0%, 1%, or 3% tomato oily extract (TOE), compared to a control (without coating), on the physicochemical and antioxidant properties of garambullo fruits stored for 15 days at 5 °C. The gelatin coatings with TOE significantly (p ≤ 0.05) delayed changes in weight loss, brix degrees, titratable acidity and pH, compared to the control during storage. Fruits coated with TOE-gelatin had a higher content of betalains, ascorbic acid, total phenols, and flavonoids. The results showed that a higher concentration of phytochemicals increased antioxidant activity in vitro; the maximum values found for Trolox equivalents per kg of fresh weight were 10.46 and 17.65 mM for the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and Trolox Equivalent Antioxidant Capacity Method (TEAC) tests, respectively. The gelatin coating with TOE-3% (COTE-3%) reduced water loss by 1.66 times, compared to the control. In addition, the fruits covered with COTE-3% showed the highest concentration of bioactive compounds during storage.