The Selenium Supplementation Influences Olive Tree Production and Oil Stability Against Oxidation and Can Alleviate the Water Deficiency Effects

Abstract

Foliar fertilization with selenium (Se) may well be beneficial in increasing the nutritional and qualitative values of food in Se-deficient regions such as the Mediterranean Basin, and may contribute to an increase in drought resistance in plants. The present study has considered detachment force, flesh firmness, pigmentation, fresh and dry weight, and oil content of olive drupes from Se fertilized olive orchards (Olea europaea L.) under drought stress and well-watered conditions. This study has also evaluated the total Se, Se amino acid, phenol, carotenoid and chlorophyll contents of EVOO, plus its oxidative stability against oxidation. While there was no change in the ripening indexes and the production of olives generally, Se application did increase the total Se, Se methionine, phenol, and carotenoid and chlorophyll contents. The higher concentration of these (bio) chemical compounds in EVOO obtained from Se fertilized plants might well suggest enhanced antioxidant activity. Consequently, EVOO obtained from Se fertilized trees possesses a higher nutritional value and, as indicated by the greater oxidative stability against oxidation, longer shelf life. In addition, under water deficient conditions, a higher fresh olive weight corresponds to a higher level of phenol, carotenoid and chlorophyll, and the chlorophyll-to-carotenoid ratio in Se fertilized trees would appear to confirm the positive role of selenium in alleviating damage caused by drought stress conditions.

Selenium biofortification in the 21st century: status and challenges for healthy human nutrition

“…In plants suffering from drought stress or heat stress, Se fertilization may sustain crop yields by alleviating ROSinduced damages via activation of cellular antioxidant systems (D'Amato et al 2018a;Iqbal et al 2015;Jóźwiak and Politycka 2019;Malerba and Cerana 2018;Sajedi et al 2011). Increased activity of antioxidant enzymes and reduced lipid peroxidation have been reported in wheat, maize and cucumber plants grown under water deficit (Nawaz et al 2016;Yao et al 2009) and in wheat plants subjected to heat stress (Iqbal et al 2015;Jóźwiak and Politycka 2019).…”

Effect of Feed Supplemented with Selenium-Enriched Olive Leaves on Plasma Oxidative Status, Mineral Profile, and Leukocyte DNA Damage in Growing Rabbits

“…Se concentrations were determined via ICP-MS (Agilent 7900, Agilent Technologies, Santa Clara, CA, USA) and an Octopole Reaction System (ORS) following the analytical method of D'Amato et al [20], while the total Ca, Mg, Fe, Cu, and Zn contents were determined using a Shimadzu AA-6200 atomic absorption spectrophotometer (Shimadzu, Tokyo, Japan), as described by Mattioli et al [18].…”

“…Similarly, Aouidi et al [19] added olive leaf powder to beef meat, thereby inhibiting lipid and protein oxidation and also improving the technological quality of the meat. Proietti et al [20] showed that the dietary intake of Se in sheep can largely offset the effects of oxidative stress on Ca 2+ homeostasis. As a consequence, some animal-originated products, e.g., meat, milk, and eggs, enriched with selenium have been developed and are currently marketed all over the world [21].…”

“…In particular, we investigated the mineral profile of rabbit plasma, the antioxidant status of the blood, and DNA damage rabbit leukocytes as biomarkers of anti-cancer effects. The selenate-treated leaves were derived from pruning olive trees treated with Se in order to reduce tree drought stress [20,22,23]. In this way, in a circular economy logic, the leaves could be used as a Se vector for rabbit feed with the aim of providing an organic source of Se with greater bioavailability [24,25] and at the same time contributing to the disposal of pruning by-products [26,27].…”

Effects of Nitrogen Foliar Fertilization on the Vegetative and Productive Performance of the Olive Tree and on Oil Quality

“…The oil and water content of the olives was determined, after fruits crashing, using the "SpectraAlyzer ZEUTEC"-NIR: Near Infra-Red". Each year, one day after harvesting (beginning of November), oil was extracted from two samples of about 2.5 kg per treatment using an artisanal mini olive-mill [23,24]. The determination of the oil chemical characteristics (acidity, peroxide number, total phenol content and fatty acid composition) and the sensory evaluation (panel test) were carried out on 3 subsamples for each oil sample following the Official Methods of Analysis [25].…”