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A comparative study was conducted to evaluate the effect of location on the chemical composition and quality of monovarietal virgin olive oils obtained from the Chétoui cultivar in relation to the fruit ripening stages. Three sites representative of two Tunisian olive growing regions were examined, Selten (region I (RI): original site of plantation of Chétoui variety in the north of the country), Ousletia and Jelma (region II (RII): in the central part of the country away from the original plantation site). In this study, Chétoui olive cultivar was found to have different responses to environmental conditions. Chétoui olive oils showed lower values in phenol and o-diphenol contents and were less stable to oxidation (weaker oxidative stability and antioxidant activity levels) when the olive trees were cultivated away from the original plantation site. These Chétoui olive oils are also characterized by decreased oil content and higher values of quality parameters such as free acidity, peroxide value and UV absorbance due probably to the drought during the flowering and olive ripening periods. Furthermore, many analytical parameters, i.e., chlorophyll pigments, carotenoids, oleic acid contents, total phenol and o-diphenol amounts, oxidative stability, antioxidative capacity and quality parameters showed nearly the same changes during fruit ripening but in different degrees depending on the site of the plantation.

Most crop species are cultivated in nutrient-deficient soils, in combination with other challenging constraints that are exacerbated by the current climate changes. The significance of micronutrient shortage in stress management is often underappreciated, although their deficiency restricts both plant growth and resistance to abiotic stresses and diseases. While the application of nutrients to growing plants is a potential strategy to improve plant resistance to abiotic stresses, seed nutrient status may also play a role in crop stress tolerance as a storage and accumulation site of nutrients. To avoid hidden hunger problems, developing countries need to increase domestic cereal production, enhance their resilience to extreme weather events, and improve their nutritional status and quality. Here, we analyze the accumulated knowledge about the effects of nutri-priming in cereal crop species with a focus on mechanisms of application and stress tolerance, keeping in mind the risk of crop damage mostly caused by global climate change, which is driving an alarming increase in the frequency and intensity of abiotic stresses. We also propose new approaches to food production, which may be promising solutions for global warming, emerging diseases, and geopolitical conflicts recognized as major drivers of food insecurity. [ABSTRACT FROM AUTHOR]

The current investigation aims to underline the impact of salicylic acid or calcium chloride seed pre-treatments on mineral status and oxidative stress markers, namely levels of electrolyte leakage (EL) and lipid peroxidation levels, measured as thiobarbituric reactive substances (TBARS), and the activity of some antioxidant enzymes in roots and leaves of plants in two barley species grown under various salt treatments. Overall, our results revealed that salinity inhibits essential nutrient absorption such as iron, calcium, magnesium and potassium and stimulates the absorption of sodium. Also, this environmental constraint induced oxidative stress in plants in comparison with the control conditions. This state of oxidative stress is reflected by an increase in TBARS content as well as the stimulation of EL values. In addition, salinity induced disturbances in the activity of antioxidant enzymes, which were mainly dependent on the applied salt concentration and the species. In addition, Hordeum marinum maintained high antioxidant enzyme activity and low levels of oxidative stress parameters, which reinforces its salt-tolerant character. Importantly, salicylic acid or calcium chloride seed priming alleviated the mineral imbalance and the oxidative damage induced by salinity. Moreover, seed priming improves iron, calcium magnesium and potassium content and limitsthe accumulation of sodium. Also, both treatments not only decrease TBARS levels and limit EL, but they also stimulate the antioxidant enzyme activities in the leaves and roots of the stressed plants as compared with stressed plants grown from non-primed seeds. Interestingly, the beneficial effects of the mentioned treatments were more notable on Hordeum vulgare species. [ABSTRACT FROM AUTHOR]

Sea fennel (Crithmum maritimum L.) is a facultative halophyte from the Apiaceae family. The variation of phenolic compounds, the antioxidant and antibacterial activities of different extracts of different organs of sea fennel were investigated. The roots, stems, leaves and seeds were collected from three bioclimatic stages of Tunisia. Solvent fractionation method (using aqueous acetone, petroleum ether and ethyl acetate) was adopted to separate the extract ingredient and to concentrate phenolics. Total phenolics, total flavonoids, and condensed tannins significantly varied between organs and localities. In leaves, the highest level of phenols was detected in the upper and sub-humid zones. However, in stems the high amounts of phenols were observed in semiarid climate. The antioxidant activity was evaluated through four different methods and the antimicrobial activity was assessed against five human pathogenic bacteria and a fungal strain. Multivariate analysis showed significant effect of organ and locality on the antioxidant properties. Results of the antibacterial activities showed significant differences among extracts and was reflected by a large spectrum of activity ranging from totally not active (Zones of inhibition (zi) < 1 mm) to very high activity (zi >16 mm). Combined statistical results allowed to select the more potent fraction to be analyzed using reversed-phase HPLC (RP-HPLC). The flavanol epigallocatechin was identified as a major phenolic compound which contributed greatly to the antioxidant capacity. The results established in this study highlighted the importance of this halophyte cash crop in the human diet as natural source of active components. [ABSTRACT FROM AUTHOR]

Salinity is a widespread abiotic stress, which has strong adverse effects on plant growth and crop productivity. Exopolysaccharides (EPS) play a crucial role in plant growth‐promoting rhizobacteria (PGPR)‐mediated improvement of plant stress tolerance. This study aimed to assess whether Glutamicibacter sp. strain producing large amounts of EPS may promote tolerance of common reed, Phragmites australis (Cav.) Trin. ex Steud., towards salt stress. This halotolerant rizhobacterium showed tolerance to salinity (up to 1 M NaCl) when cultivated on Luria‐Bertani (LB) medium. Exposure to high salinity (300 mM NaCl) significantly impacted the plant growth parameters, but this adverse effect was mitigated following inoculation with Glutamicibacter sp., which triggered higher number of leaves and tillers, shoot fresh weight/dry weight, and root fresh weight as compared to non‐inoculated plants. Salt stress increased the accumulation of malondialdehyde (MDA), polyphenols, total soluble sugars (TSSs), and free proline in shoots. In comparison, the inoculation with Glutamicibacter sp. further increased shoot polyphenol content, while decreasing MDA and free proline contents. Besides, this bacterial strain increased tissue Ca+ and K+ content concomitant to lower shoot Na+ and root Cl− accumulation, thus further highlighting the beneficial effect of Glutamicibacter sp. strain on the plant behavior under salinity. As a whole, our study provides strong arguments for a potential utilization of EPS‐producing bacteria as a useful microbial inoculant to alleviate the deleterious effects of salinity on plants. [ABSTRACT FROM AUTHOR]