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Biostimulants contribute to the physiological growth of plants by enhancing the quality characteristics of fruit without harming the environment. In addition, biostimulants applied to plants strengthen nutritional efficiency, abiotic stress tolerance, and fruit biochemical traits. We investigated the effectiveness of specific organic biostimulants. Five treatments were tested: (1) control (H2O, no biostimulants); (2) Magnablue + Keyplex 350 (Mgl + Kpl350); (3) Cropobiolife + Keyplex 120 (Cpl + Kpl120); (4) Keyplex 120 (Kpl120); and (5) Magnablue + Cropobiolife + Keyplex 120 (Mgl + Cpl + Kpl120) on the mineral uptake and physiology in black chokeberry (Aronia) plants, as well as the quality of their berries. The different treatments were applied to three-year-old chokeberry plants, and the experimental process in the field lasted from May to September 2022 until the harvest of ripe fruits. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) revealed that the fifth treatment significantly increased concentrations of P, Ca, and K. Additionally, the fifth treatment enhanced photochemical efficiency (Fv/Fm), water-splitting efficiency (Fv/Fo) in PSII, and the performance index (PI) of both PSI and PSII in chokeberry leaves. Improvements in photosynthesis, such as CO2 assimilation (A), transpiration (E), and water-use efficiency (A/E), were also noted under biostimulant applications. Upon harvesting the ripe fruits, part of them was placed at room temperature at 25 °C, while the rest were stored at 4 °C, RH 90% for 7 days. The cultivation with biostimulants had beneficial effects on the maintenance of flesh consistency, ascorbic acid concentration, and weight of berries at 4 and 25 °C, especially in the 5th treatment. Moreover, the total antioxidant capacity, anthocyanin concentration, and total phenols of the berries were notably higher in the third and fifth treatments compared to the control. These data suggest that selecting appropriate biostimulants can enhance plant yield and fruit quality by potentially activating secondary metabolite pathways. [ABSTRACT FROM AUTHOR]

Mentha spicata L., Origanum dictamnus L., and Origanum onites L. are aromatic plants that produce very important essential oils. They are considered model plants with beneficial health properties due to their antioxidant content. Enhancing the yield while maintaining the quality of essential oil is of significant commercial importance. Salinization and drought cause various effects on the yield and quality of the bioactive constituents in essential oil. By assessing the response of these plants and their secondary metabolites accumulation to different salt stress and irrigation levels, this study aims to gain insights into how plants adapt to and cope with salinity and drought. A pot experiment was conducted in the spring of 2020 to assess the effect of salinity and drought stress on the growth and essential oils content of the three aromatic plant species mentioned above. The soil mixture used was perlite and peat in a ratio of 1:1:6, while four salinity treatments (25, 50, 100, and 150 mΜ NaCl) and two levels of irrigation were applied (100% and 50%). Salinity significantly affects total chlorophyll concentration especially in higher concentrations (100 and 150 mM) in M. spicata plants, especially under 50% soil water irrigation. Under the same conditions, M. spicata contained the higher proline concentration, which was significantly greater than that in O. dictamnus and O. onites. Similar variations of malondialdehyde and hydrogen hyperoxide were revealed among the three species, with significantly higher values in M. spicata when subjected to both excess salinity and drought conditions. The major compounds identified in M. spicata were carvone, in O. dictamnus carvacrol, and p-cymene and in O. onites carvacrol. It is important to highlight that O. onites had the highest concentration of essential oil, and that the concentration increased with the increase of NaCl. This suggests that the presence of NaCl in the soil may have a stimulating effect on the production of essential oil in O. onites. However, it is plausible that the stress caused by NaCl triggers a physiological response in O. onites, leading to increased production of essential oil. This could be a protective mechanism to enhance the plant's resistance to the stressor. Overall, O. onites and O. dictamnus appeared to be more resistant to these stress conditions than M. spicata, since they maintained their growth and essential oil quality indicators at higher levels. These two species possess mechanisms that prevent or minimize lipid peroxidation, thus protecting their cell membranes and maintaining their ultrastructure integrity. [ABSTRACT FROM AUTHOR]

Since drought stress is one of the key risks for the future of agriculture, exploring the molecular mechanisms of photosynthetic responses to water deficit stress is, therefore, fundamental. By using chlorophyll fluorescence imaging analysis, we evaluated the responses of photosystem II (PSII) photochemistry in young and mature leaves of Arabidopsis thaliana Col-0 (cv Columbia-0) at the onset of water deficit stress (OnWDS) and under mild water deficit stress (MiWDS) and moderate water deficit stress (MoWDS). Moreover, we tried to illuminate the underlying mechanisms in the differential response of PSII in young and mature leaves to water deficit stress in the model plant A. thaliana. Water deficit stress induced a hormetic dose response of PSII function in both leaf types. A U-shaped biphasic response curve of the effective quantum yield of PSII photochemistry (ΦPSII) in A. thaliana young and mature leaves was observed, with an inhibition at MiWDS that was followed by an increase in ΦPSII at MoWDS. Young leaves exhibited lower oxidative stress, evaluated by malondialdehyde (MDA), and higher levels of anthocyanin content compared to mature leaves under both MiWDS (+16%) and MoWDS (+20%). The higher ΦPSII of young leaves resulted in a decreased quantum yield of non-regulated energy loss in PSII (ΦNO), under both MiWDS (−13%) and MoWDS (−19%), compared to mature leaves. Since ΦNO represents singlet-excited oxygen (1O2) generation, this decrease resulted in lower excess excitation energy at PSII, in young leaves under both MiWDS (−10%) and MoWDS (−23%), compared to mature leaves. The hormetic response of PSII function in both young and mature leaves is suggested to be triggered, under MiWDS, by the intensified reactive oxygen species (ROS) generation, which is considered to be beneficial for activating stress defense responses. This stress defense response that was induced at MiWDS triggered an acclimation response in A. thaliana young leaves and provided tolerance to PSII when water deficit stress became more severe (MoWDS). We concluded that the hormesis responses of PSII in A. thaliana under water deficit stress are regulated by the leaf developmental stage that modulates anthocyanin accumulation in a stress-dependent dose. [ABSTRACT FROM AUTHOR]