Biochemical Characteristics and Elemental Composition Peculiarities of <i>Rheum tataricum</i> L. in Semi-Desert Conditions and of European Garden Rhubarb

Biochemical and mineral peculiarities of plants inhabiting desert and semi-desert areas may provide important information about the mechanism of their adaptability and reveal the prospects of their utilization. Rheum tataricum L., known for its high tolerance to drought, salinity, and nutritional deficiency, is the least studied species of wild rhubarb. Using biochemical and ICP-MS analysis, the antioxidant status and mineral composition of R. tataricum were determined. Extremely high levels of antioxidant activity (148–155 mg GAE g−1 d.w.), polyphenols (24.6–25.1 mg GAE g−1 d.w.) and carotenoids (1.94 mg-eq β-carotene g−1 d.w.) were revealed in roots, proline in leaves (71.1 ± 6.2 mg kg−1 d.w.) and malic acid in stems (3.40 ± 0.50 mg g−1 d.w.). Compared to garden rhubarb, R. tataricum demonstrated significant root–leaves translocation of Li, Se, Si, and Mo, known to participate in plant antioxidant defense. Under high levels of Ca, Na, Mg, Fe, Cr and Si in soil, R. tataricum demonstrated the ability to significantly increase the accumulation of these elements in roots, showing a hyperaccumulation ability for Sr. The first broad picture of R. tataricum biochemical and mineral characteristics in semi-desert habitat and its nutritional value indicate the prospects of R. tataricum utilization in plant breeding, medicine, and nutrition

Effect of Foliar Sodium Selenate and Nano Selenium Supply on Biochemical Characteristics, Essential Oil Accumulation and Mineral Composition of Artemisia annua L.

Selenium (Se) biofortification of aromatic plants is a promising strategy to produce valuable functional food with high biological activity and enhanced essential oil yield. The experiment carried out in 2021 and 2022 on A. annua treated with sodium selenate or nano-Se sprayed on foliar apparatus demonstrated a significant increase in photosynthetic pigments, pectin, waxes, macro- and microelements and a decrease in malonic dialdehyde (MDA) accumulation. Contrary to literature reports, neither selenate nor nano-Se showed a beneficial effect on essential oil accumulation; the oil yield did not differ between the selenate treated and control plants but was halved by the nano-Se application. Extremely high variations in the number of essential oil components, as well as in the eucalyptol, artemisia ketone, camphor and germacrene D ratio in the 2021 and 2022 experiments were recorded. The analysis of the 2016&ndash;2022 data for oil yield and composition in the control plants revealed a direct correlation between the number of components and of solar flares, and a negative correlation between oil yield and the percentage of spotless days. Both control plants and plants fortified with selenium showed higher levels of germacrene D and lower levels of artemisia ketone in 2022, characterized by more remarkable solar activity compared to 2021. Nano-Se supply resulted in the highest percentage of germacrene D accumulation. The results of the present research highlight the importance of the solar activity effect on the essential oil yield and quality of aromatic plants

Effect of Foliar Selenate Supplementation on Biochemical Characteristics of Purslane Weed (<i>Portulaca oleracea</i> L.)

The high biological activity of cultivated and wild purslane offers broad possibilities for utilizing this plant in medicine and human nutrition. To assess the prospects of obtaining new functional food products based on the wild form of P. oleracea L., foliar biofortification of this species with sodium selenate (VI) was carried out, and the changes in leaf and seed biochemical characteristics were investigated. Selenium significantly enhanced plant yield, photosynthetic pigments and the ascorbic acid content, and showed a tendency to seed productivity increase. The application of selenium augmented quinic acid content in leaves by 1.7 times but did not affect the oxalic acid content. Oxalic acid prevailed in wild purslane and quinic acid in cultivated purslane (cv. Makovey). Seed oil in Se-enriched purslane was characterized by a two-fold decrease in saturated fatty acids and squalene and 2.3-fold decrease in malonic dialdehyde content, along with a 1.4-fold increase in ascorbic acid. Selenium supplementation resulted in an increase in total lipids and mono- and di-unsaturated fatty acids and did not affect the concentration of ω-3 fatty acids and sterol accumulation. Among the identified sterols, only the minor ones (fucosterol, 7-stigmasterol and ∆7-avenosterol) showed a slight decrease upon Se supply. Compared to seeds of cv. Makovey, wild purslane seeds had higher levels of antioxidant activity by a factor of 2 and of polyphenols by a factor of 3.2 but did not differ significantly in oil fatty acid composition. The results indicate the importance of wild purslane leaves/seeds both fortified and not fortified with Se in human nutrition and medicine

Varietal Differences in Juice, Pomace and Root Biochemical Characteristics of Four Rhubarb (Rheum rhabarbarum L.) Cultivars

The complex evaluation of varietal biochemical differences in rhubarb juice, pomace and roots is highly useful to develop an efficient processing technology. Research was carried out to compare four rhubarb cultivars (Malakhit, Krupnochereshkovy, Upryamets and Zaryanka) in terms of the quality and antioxidant parameters of juice, pomace and roots. The laboratory analyses showed a high juice yield (75&ndash;82%) with a relatively high content of ascorbic acid (125&ndash;164 mg L&minus;1) and other organic acids (16&ndash;21 g L&minus;1). Citric, oxalic and succinic acids accounted for 98% of the total acids amount. The juice of the cultivar Upryamets demonstrated high levels of the natural preservatives sorbic (36.2 mg L&minus;1) and benzoic acids (11.7 mg L&minus;1), which are highly valuable in juice production. The juice pomace proved to be an excellent source of pectin and dietary fiber, whose concentrations reached 21&ndash;24% and 59&ndash;64%, respectively. The total antioxidant activity decreased according to the following sequence: root pulp (161&ndash;232 mg GAE g&minus;1 d.w.) &gt; root peel (115&ndash;170 mg GAE g&minus;1 d.w.) &gt; juice pomace (28.3&ndash;34.4 mg GAE g&minus;1 d.w.) &gt; juice (4.4&ndash;7.6 mg GAE g&minus;1 f.w.), suggesting that root pulp is a highly valuable antioxidant source. The results of this research highlight the interesting prospects of the complex rhubarb plant processing for the production of juice, containing a wide spectrum of organic acids and natural stabilizers (sorbic and benzoic acids), dietary fiber and pectin (juice pomace) and natural antioxidants (roots)

Effect of Seed Spaceflight Storage on Tomato Fruit Quality and Peel/Pulp Mineral and Antioxidant Distribution

The spaceflight storage of seeds is known to cause mutations affecting both their quality and the mature plants originating from them. To study the effects of space stress, tomato seeds of two cultivars (Lotus and Autumn rhapsody) were subjected to half a year of storage at the International Space Station (ISS), and then, sown in a greenhouse to produce tomato fruits. The space-treated plants gave smaller fruits with a stable total yield not significantly different from that of the control plants. Space-treated tomatoes showed significantly higher levels of dry matter, dietary fiber, monosaccharides and citric and malic acids and lower values of oxalic acid compared to the control plants. The pulp of space-treated fruits had 1.44–1.70 times lower levels of carotenoids, while their peel contained a 1.27–1.90 times higher pigment amount compared to the control plants. No significant changes in the total antioxidant activity (AOA), photosynthetic pigments and phenolic (TP) and proline content were recorded in the fruits due to seed spaceflight storage. Contrarily, space-treated tomatoes showed decreased levels of Ca, Sr and Mo and increased Se both in the fruit pulp and peel. The concentration of Fe and especially Pb was lower in space-treated fruit pulp. Positive correlations between Se and dry matter, Ca and Sr, Ca and Co, Ca and Fe, and Cr and carotenoids, and negative correlations between Se and Mo, Se and K, and Mo and dry matter were recorded. The results indicate that seed stress caused by long-term spaceflight affects both the biochemical characteristics and mineral composition of tomato fruits and causes the peel/pulp redistribution of carotenoids as well as macro- and micro-elements, improving Se accumulation levels in the fruit peel