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The objective of this work was to determine the responses of tomato seed priming with CNMs (carbon nanomaterials), evaluating the changes in germination and biochemical compounds as well as the effect on the growth of tomato seedlings. Five concentrations of CNMs (10, 100, 250, 500, and 1000 mg L−1) were evaluated, as well as an absolute control and a sonicated control. The results showed that seed priming with CNMs did not affect the germination rate of the tomato seeds; however, it negatively affected the vigor variables, such as the root length (up to 39.2%) and hypocotyl biomass (up to 33%). In contrast, the root biomass was increased by the application of both carbon nanotubes and graphene up to 127% in the best case. Seed priming with carbon nanotubes (1000 mg L−1) decreased the plant height (29%), stem diameter (20%), fresh shoot biomass (63%), fresh root biomass (63%), and dry shoot biomass (71%). Seed priming with graphene increased the content of chlorophylls (up to 111%), vitamin C (up to 78%), β-carotene (up to 11 fold), phenols (up to 85%), and flavonoids (up to 45%), as well as the H2O2 content (up to 215%). Carbon nanotubes (CNTs) increased the enzymatic activity (phenylalanine ammonia lyase (PAL), ascorbate peroxidase (APX), glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT). In addition, seed priming with high concentrations of CNMs showed negative effects. Seed priming with carbon nanomaterials can potentially improve the development of the tomato crop; therefore, this technique can be used to induce biostimulation and provides an easy way to apply carbon nanomaterials.

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.

Nanotechnology is a potential and emerging field with multiple applications in different areas of study. The beneficial effects of the use of nanoparticles in agriculture have already been proven. The objective of this research was to determine if the foliar application of Cu nanoparticles (NPs) could increase the content of the bioactive compounds in tomato fruits. Our study considered four treatments with different concentrations of Cu nanoparticles (50, 125, 250, 500 mg L−1, diameter 50 nm) applied twice during the development of the culture. The effects on the fruit quality and the contents of the antioxidant compounds were determined. The application of the Cu nanoparticles induced the production of fruits with greater firmness. Vitamin C, lycopene, and the ABTS antioxidant capacity increased compared to the Control. In addition, a decrease in the ascorbate peroxidase (APX) and glutathione peroxidase (GPX) enzymatic activity was observed, while the superoxide dismutase (SOD) and catalase (CAT) enzymes showed a significant increase. The application of Cu NPs induced a greater accumulation of bioactive compounds in tomato fruits.

The consumption of food with a high content of bioactive compounds is correlated with the prevention of chronic degenerative diseases. Tomato is a food with exceptional nutraceutical value; however, saline stress severely affects the yield, the quality of fruits, and the agricultural productivity of this crop. Recent studies have shown that seed priming can mitigate or alleviate the negative effects caused by this type of stress. However, the use of carbon nanomaterials (CNMs) in this technique has not been tested for this purpose. In the present study, the effects of tomato seed priming with carbon nanotubes (CNTs) and graphene (GP) (50, 250, and 500 mg L−1) and two controls (not sonicated and sonicated) were evaluated based on the content of photosynthetic pigments in the leaves; the physicochemical parameters of the fruits; and the presence of enzymatic and non-enzymatic antioxidant compounds, carotenoids, and stress biomarkers such as hydrogen peroxide (H2O2) and malondialdehyde (MDA) in the leaves and fruits of tomato plants without saline stress and with saline stress (50 mM NaCl). The results show that saline stress in combination with CNTs and GP increased the content of chlorophylls (9.1–21.7%), ascorbic acid (19.5%), glutathione (≈13%), proteins (9.9–11.9%), and phenols (14.2%) on the leaves. The addition of CNTs and GP increased the activity of enzymes (CAT, APX, GPX, and PAL). Likewise, there was also a slight increase in the content of H2O2 (by 20.5%) and MDA (3.7%) in the leaves. Salinity affected the quality of tomato fruits. The physico-chemical parameters and bioactive compounds in both the stressed and non-stressed tomato plants were modified with the addition of CNTs and GP. Higher contents of total soluble solids (25.9%), phenols (up to 144.85%), flavonoids (up to 37.63%), ascorbic acid (≈28%), and lycopene (12.4–36.2%) were observed. The addition of carbon nanomaterials by seed priming in tomato plants subjected to saline stress modifies the content of bioactive compounds in tomato fruits and improves the antioxidant defense system, suggesting possible protection of the plant from the negative impacts of stress by salinity. However, analysis of the mechanism of action of CNMs through seed priming, in greater depth is suggested, perhaps with the use of omics sciences.

Tomato is one of the most economically important vegetables worldwide and is constantly threatened by various biotic and abiotic stress factors reducing the quality and quantity in the production of this crop. As an alternative to mitigate stress in plants, carbon nanomaterials (CNMs) have been used in agricultural areas. Therefore, the objective of the present work was to evaluate the antioxidant responses of tomato seedlings to the application via foliar and drench of carbon nanotubes (CNTs) and graphene (GP). Different doses (10, 50, 100, 250, 500, and 1000 mg L−1) and a control were evaluated. The results showed that the fresh and dry root weight increased with the application of CNMs. Regarding the antioxidant responses of tomato seedlings, the application of CNMs increased the content of phenols, flavonoids, ascorbic acid, glutathione, photosynthetic pigments, activity of the enzyme’s ascorbate peroxidase, glutathione peroxidase, catalase, and phenylalanine ammonia lyase as well as the content of proteins. Therefore, the use of carbon-based nanomaterials could be a good alternative to induce tolerance to different stress in tomato crop.

This study investigated the effects of two nanofertilizers (NFs): copper nanoparticles (NPs) synthesised using cotton (CuC) and chitosan (CuCh) as well as two biofertilizers (BFs), nopal extract (NE) and commercial Biojal® worm humus (WH), on the growth of black bean seedlings. The treatments consisted of applying 50 mg L−1 of CuC, 50 mg L−1 of CuCh, 50 mg L−1 of NE, 100 mg L−1 of WH, their respective combinations, and an absolute control that consisted of distilled water. The CuC, CuCh, WH, and WH + CuC leaf applications resulted in an increase in plant height by 34.4%, 19.5%, 25.7%, and 20.3%, respectively. Furthermore, the CuC and WH applications led to an increase in the number of leaves by 53.2% and 36.9%, respectively. However, the addition of NE + CuC resulted in a 37.4% decrease in dry weight. A total of 44 metabolites were identified, including 7 sugars, 17 amino acids, 12 organic acids, 4 nucleosides, 1 alcohol, and 3 miscellaneous metabolites. The NE + CuC and WH treatments resulted in a notably higher concentration of various metabolites, including amino acids, organic acids, and sugars. Conversely, the CuCh treatment led to an increased concentration of nucleosides, amino acids, trigonelline, and nicotinamide adenine dinucleotide (NAD+).