The physiological responses of habanero pepper plants (Capsicum chinense Jacq.) to foliar applications of zinc sulphate and zinc nano-fertilizer were evaluated in greenhouse trials. The effect of the supplement on fruit quality of habanero pepper was particularly observed. Habanero pepper plants were grown to maturity, and during the main stages of phenological development, they were treated with foliar applications of Zn at concentrations of 1000 and 2000 mg L⁻¹ in the form of zinc sulfate (ZnSO₄) and zinc oxide nanoparticles (ZnO NPs). Additional Zn was not supplied to the control treatment plants. ZnO NPs at a concentration of 1000 mg L⁻¹ positively affected plant height, stem diameter, and chlorophyll content, and increased fruit yield and biomass accumulation compared to control and ZnSO₄ treatments. ZnO NPs at 2000 mg L⁻¹ negatively affected plant growth but significantly increased fruit quality, capsaicin content by 19.3%, dihydrocapsaicin by 10.9%, and Scoville Heat Units by 16.4%. In addition, at 2000 ZnO NPs mg L⁻¹ also increased content of total phenols and total flavonoids (soluble + bound) in fruits (14.50% and 26.9%, respectively), which resulted in higher antioxidant capacity in ABTS (2,2′azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric reducing antioxidant power) (15.4%, 31.8%, and 20.5%, respectively). These results indicate that application of ZnO NPs could be employed in habanero pepper production to improve yield, quality, and nutraceutical properties of fruits.

The effects of zinc oxide nanoparticles on seed germination and seedling growth of Capsicum annuum L. were determined in this research. Total phenols content, total flavonoids, and condensed tannins, as well as 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant capacity was determined. Results indicated that treatment with zinc oxide nanoparticles (ZnO-NPs) improved seed germination rate during the first seven days. The seed vigor germination increased 123.50%, 129.40% and 94.17% by treatment with ZnO-NPs suspensions at 100, 200 and 500 ppm, respectively. The morphological parameters tested revealed that ZnO-NPs treatments did not significantly affect plumule development, but they had a significant impact (p ≤ 0.01) on radicle length. Suspensions at 100, 200 and 500 ppm of ZnO-NPs inhibited seedling radicle growth and promoted accumulation of phenolic compounds, with a phytotoxic effect in this organ. Results suggested that zinc oxide nanoparticles influence seed vigor and seedling development and promoted the accumulation of desirable phenolic compounds in the radicle.

The objective of this review is to present a compilation of the application of various biostimulants in strawberry plants. Strawberry cultivation is of great importance worldwide, and, there is currently no review on this topic in the literature. Plant biostimulation consists of using or applying physical, chemical, or biological stimuli that trigger a response—called induction or elicitation—with a positive effect on crop growth, development, and quality. Biostimulation provides tolerance to biotic and abiotic stress, and more absorption and accumulation of nutrients, favoring the metabolism of the plants. The strawberry is a highly appreciated fruit for its high organoleptic and nutraceutical qualities since it is rich in phenolic compounds, vitamins, and minerals, in addition to being a product with high commercial value. This review aims to present an overview of the information on using different biostimulation techniques in strawberries. The information obtained from publications from 2000–2022 is organized according to the biostimulant’s physical, chemical, or biological nature. The biochemical or physiological impact on plant productivity, yield, fruit quality, and postharvest life is described for each class of biostimulant. Information gaps are also pointed out, highlighting the topics in which more significant research effort is necessary.

The objective of this experiment was to evaluate the effects of grafting, zinc oxide nanoparticles (ZnO NPs), and their interaction on the nutritional composition of bell pepper plants. The treatments evaluated included grafted and non-grafted pepper plants with four concentrations of ZnO NPs (0, 10, 20, 30 mg L⁻¹) applied to the foliage. The following parameters were evaluated: content of N, P, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Zn²⁺, Fe²⁺, Cu²⁺, total antioxidants, ascorbic acid, total phenols, glutathione, total proteins, fruit firmness, and total soluble solids. Grafting increased the content of N 12.2%, P 15.9%, K⁺ 26.7%, Mg²⁺ 20.3%, Mn²⁺ 34.7%, Zn²⁺ 19.5%, Fe²⁺ 18.2%, Cu²⁺ 11.5%, antioxidant capacity 2.44%, ascorbic acid 4.63%, total phenols 1.33%, glutathione 7.18%, total proteins 1.08%, fruit firmness 8.8%. The application of 30 mg L⁻¹ ZnO NPs increased the content of N 12.3%, P 25.9%, Mg²⁺ 36.8%, Mn²⁺ 42.2%, Zn²⁺ 27%, Fe²⁺ 45%, antioxidant activity 13.95%, ascorbic acid 26.77%, total phenols 10.93%, glutathione 11.46%, total proteins 11.01%, and fruit firmness 17.7% compared to the control. The results obtained demonstrate the influence of the use of grafts and ZnO NPs as tools that could improve the quality and nutrient content in fruits of bell pepper crops.

The common fig is an edible fruit which is appreciated for its organoleptic characteristics and high commercial value. Several factors, including mineral nutrition, affect fig production. Macronutrients fulfill specific functions in the metabolism of plants, affecting some functions when they are at low levels. So, in the present investigation, the visual symptoms of nitrogen, phosphorus, potassium, calcium, and magnesium deficiencies were identified and characterized, as well as their effects on vegetative growth and the concentration of minerals in fig tree tissues, using the missing element technique in a controlled hydroponic system. N was the element that most affected vegetative growth, causing smaller stem diameter, leaf area, and dry weight. Treatments without P and K followed. In addition, significant differences were found in the mineral concentration in leaf, stem, and root, with various interactions of antagonism and synergism observed according to the absence of each element.

Plant microbial fuel cells (P-MFCs) are sustainable and eco-friendly technologies, which use plant root exudates to directly nourish the electrochemically active bacteria (EABs) to generate sustainable electricity. However, their use in evaluating plant growth has been insufficiently studied. In this study, interconnection between plant growth and the production of bioelectricity was evaluated by using P-MFCs inoculated with 642.865 mL ≅ 643 mL of livestock’s urine such as cow urine, goat urine, and sheep urine. The greatest mean stem diameter of 0.52 ± 0.01 cm was found in P-MFC-3 inoculated with goat urine, while the P-MFC-2 treated with cow urine reached a higher average number of roots with a value of 86 ± 2.50 (95% improvement) (p < 0.05). Besides, P-MFC-4 presented greater height of 50.08 ± 0.67 cm. For polarization curve experiment a higher maximum power density of 132 ± 11.6 mW m⁻² (931 mA m⁻²) was reached with cow urine; in turn, with regard to the long-term operation, the same reactor indicated a higher maximum average power density of 43.68 ± 3.05 mW m⁻². The study’s findings indicated that Stevia P-MFC inoculated with urine was a good option to increase the biomass amount for the agricultural plants along with power generation. Further, this study opens the way for more investigation of evaluating the impact of P-MFC on plant growth.