Background: The study examined the impact of varying the concentrations of zinc (Zn) on plant responses, particularly on photosynthetic and oxidative metabolic processes. This investigation aimed to distinguish between the beneficial and harmful effects of Zn on plants, highlighting significant nutrient supply concerns. Methods: The investigation methods were centered around non-invasive methods, such as biophoton emission (delayed fluorescence—DF, ultra-weak bioluminescence—UWLE), fluorescence induction (F_v/F_m) measurements, chlorophyll content estimation (SPAD) and vegetation index (NDVI) determination. Furthermore, the analytical determination of lipid oxidation (MDA level) and antioxidant capacity (FRAP) as well as gene expression studies of the antioxidative enzymes glutathione reductase (GR), glutathione S-transferase (GST) and lipoxygenase (LOX) for essential Zn and nonessential cadmium (Cd) were also carried out in order to clarify toxic symptoms through different Zn investigation approaches. Results: It was possible to identify a metabolic enhancement from 1000 µM; however, stress symptoms from the 2000 µM Zn treatment were noted for both the investigated photosynthetic and oxidative processes. The outcomes of this research contribute to the improvement of Zn mineral-supplementation technology, which is essential for maize growth, and the optimization of agricultural practices.

Sugar beet (Beta vulgaris L.) is very sensitive to fluctuations in micronutrient availability, and either an excess or a shortage of boron (B) may reduce the plant’s development and its ability to withstand stress. B is essential for photosynthesis and cell wall integrity, but the physiological requirements for an optimal supply during early development remain unclear. The photosynthetic efficiency and oxidative stress reactions of sugar beet seedlings were tested under five different B concentrations: 0, 50, 500, 1000, and 2000 µM H₃BO₃. Integrating non-invasive methods like SPAD, delayed fluorescence (DF), and maximum quantum efficiency of PSII (Fv/Fm) with red–green–blue (RGB) imaging enabled the detailed processing of both the initial and decay phases of DF. According to the results, SPAD and Fv/Fm were not sensitive indicators of early B stress; however, DF decay slopes and red–green–blue pixel distribution distinguished between optimum (500 µM), inadequate (0 µM), and hazardous (2000 µM) treatments. Moreover, lipid oxidation-related biochemical analyses were used to evaluate the ferric reducing antioxidant capacity (FRAP) and malondialdehyde (MDA) concentration. At the extremes of insufficiency and toxicity, MDA levels demonstrated enhanced lipid peroxidation, while FRAP increased with B concentration. The outcome of the research revealed optimum (500 µM) and toxicity-inducing (2000 µM) concentrations at early stages of sugar beet development. The study highlights that the combined use of DF kinetics and RGB analysis provides valuable, non-invasive markers for the early identification of B-stress, which is also confirmed by biochemical indicators, thereby promoting more efficient micronutrient management in sugar beet cultivation.

Background: The beet moth, Scrobipalpa ocellatella Boyd, 1858 (Lep.: Gelechiidae), is an increasingly important pest whose climate-driven expansion threatens sugar beet (Beta vulgaris L.) production in Europe. This study aimed to characterize the structural, physiological, biochemical, and molecular responses of sugar beet to infestation. Methods: Plants were analysed using computed tomography (CT), SPAD and NDVI measurements, HPLC-based sugar analysis, FRAP and MDA assays, and RT-qPCR of antioxidant-related genes. Results: CT imaging enabled non-destructive detection of larvae (mean length: 7.32 ± 0.73 mm) and pest-induced cavities (982.20 ± 316.04 mm³). SPAD did not differ significantly among treatments, whereas NDVI was consistently reduced in infested plants, declining from 0.648 ± 0.031 in non-infested plants to 0.593 ± 0.038 in infested-treated plants and 0.611 ± 0.021 in infested-untreated plants at the first sampling. Infestation induced pronounced oxidative stress, with FRAP increasing from 14.102 ± 0.943 to 25.471 ± 0.922 µg AA eq g⁻¹ FW and MDA from 558.065 ± 21.819 to 1325.806 ± 16.762 nmol g⁻¹ FW in untreated infested plants. Antioxidant gene expression was significantly upregulated, particularly for SOD, CAT, APX, DHAR, MDAR, and GPX. Conclusions: S. ocellatella infestation triggered coordinated oxidative stress responses in sugar beet, while CT and NDVI proved useful for early damage detection.

Background: In our previous research, we investigated the effects of different boron concentrations on photosynthetic and oxidative processes. The aim of this study was to examine in greater detail the responses to changes in boron availability, with particular emphasis on the antioxidant defense system and the expression of genes involved in sugar synthesis that play a role in stress responses. Methods: Sugar beet plants grown under controlled conditions were treated with boric acid solutions at six different concentrations (0, 50, 100, 500, 1000, and 2000 µM). We examined the relative expression of genes associated with antioxidant defense and raffinose biosynthesis, and analyzed the concentrations of sugars, vitamin C, and certain organic acids using HPLC, and we also performed FRAP and MDA assays. Results: Based on the gene expression results, the expression of several genes associated with antioxidant defense reached its lowest level at the 500 µM treatment. Glucose concentration increased significantly at the 100 and 500 µM treatment levels, while fructose concentration increased significantly at the 50, 100, and 2000 µM treatment levels. Conclusions: Our results suggest that changes in boron availability influence several interrelated processes of antioxidant defense and primary metabolism during the early developmental stage of sugar beet.