Effect of Selenium and Garlic Extract Treatments of Seed-Addressed Lettuce Plants on Biofortification Level, Seed Productivity and Mature Plant Yield and Quality.

The enhancement of the plant seed yield and quality represents the basis of the successful productivity of the deriving crop. The effect of single and combined foliar treatments of lettuce plants with sodium selenate and garlic bulb extract on seed yield and quality and on mature plant biochemical characteristics was investigated using four lettuce cultivars (Bouquet, Picnic, Moskovsky parnikovy and Cavalier). The seed production of plants treated with Se increased by 20-41%, compared to the untreated control plants, while the augmentation was as much as 10-23% and 17-27% under garlic extract and the joint application of Se and garlic, respectively. Garlic extract stimulated the accumulation of Se in lettuce seeds, which rose by 1.21-1.29 times compared to the Se-treated plants. The proline levels in lettuce seeds exceeded the corresponding values recorded in the control ones by 1.32-1.64 times in the case of the Se supply, 1.10-1.47 times upon garlic extract application and 1.09-1.31 times under the combined Se/garlic treatment. All the treatments given to lettuce plants increased the leaf weight by 1.10-1.30 times, compared to the untreated control. The seed Se levels positively correlated with the leaf weight (r = 0.621; p < 0.005), chlorophyll (r = 0.672, p < 0.002) and total antioxidant activity (AOA; r = 0.730, p < 0.001) of plants grown from these seeds. Positive correlations were also recorded between the seed proline content and lettuce plant leaf weight, chlorophyll and AOA (r = 0.868, 0.811 and 0.815, respectively, at p < 0.001). Lettuce yield was positively correlated with the leaf AOA, chlorophyll and ascorbic acid content (r = 0.942, 0.921 and 0.665, respectively, at p < 0.001). The results indicate high prospects of Na2SeO4 and garlic extract application to seed-addressed lettuce plants, to improve seed productivity and quality, as well as lettuce yield and quality.

Effect of Sodium Selenate and Selenocystine on Savoy Cabbage Yield, Morphological and Biochemical Characteristics under Chlorella Supply.

Biofortification of Brassica oleracea with selenium (Se) is highly valuable both for human Se status optimization and functional food production with direct anti-carcinogenic activity. To assess the effects of organic and inorganic Se supply for biofortifying Brassica representatives, foliar applications of sodium selenate and selenocystine (SeCys2) were performed on Savoy cabbage treated with the growth stimulator microalgae Chlorella. Compared to sodium selenate, SeCys2 exerted a stronger growth stimulation of heads (1.3 against 1.14 times) and an increase of leaf concentration of chlorophyll (1.56 against 1.2 times) and ascorbic acid (1.37 against 1.27 times). Head density was reduced by 1.22 times by foliar application of sodium selenate and by 1.58 times by SeCys2. Despite the greater growth stimulation effect of SeCys2, its application resulted in lower biofortification levels (2.9 times) compared to sodium selenate (11.6 times). Se concentration decreased according to the following sequence: leaves > roots > head. The antioxidant activity (AOA) was higher in water extracts compared to the ethanol ones in the heads, but the opposite trend was recorded in the leaves. Chlorella supply significantly increased the efficiency of biofortification with sodium selenate (by 1.57 times) but had no effect in the case of SeCys2 application. Positive correlations were found between leaf and head weight (r = 0.621); head weight and Se content under selenate supply (r = 0.897-0.954); leaf ascorbic acid and total yield (r = 0.559), and chlorophyll (r = +0.83-0.89). Significant varietal differences were recorded for all the parameters examined. The broad comparison performed between the effects of selenate and SeCys2 showed significant genetic differences as well as important peculiarities connected with the Se chemical form and its complex interaction with Chlorella treatment.

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 (75-82%) with a relatively high content of ascorbic acid (125-164 mg L-1) and other organic acids (16-21 g L-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-1) and benzoic acids (11.7 mg L-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 21-24% and 59-64%, respectively. The total antioxidant activity decreased according to the following sequence: root pulp (161-232 mg GAE g-1 d.w.) > root peel (115-170 mg GAE g-1 d.w.) > juice pomace (28.3-34.4 mg GAE g-1 d.w.) > juice (4.4-7.6 mg GAE g-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).

Joint Cultivation of Allium ursinum and Armoracia rusticana under Foliar Sodium Selenate Supply.

Despite the high value of ramson (Allium ursinum) in medicine and nutrition, it is not cultivated in open fields due to the need for shading as well as weeding during the early crop stages. Research was carried out in an open field with the aim to improve A. ursinum growth, through its intercropping with Armoracia rusticana (horseradish). In the latter context, with and without sodium selenate application, ramson and horseradish showed reciprocal growth stimulation, as ramson biomass increased by 1.28 times and horseradish root biomass by 1.7 times. The biofortification level of horseradish roots increased from 5.9 to 9.6 times due to joint plant growth under selenium (Se) supply. The opposite phenomenon was recorded for ramson leaves, as the biofortification level decreased from 11.7 in the case of Se supplementation to 6.7 in plants supplied with sodium selenate when jointly cultivated with horseradish. Among the tested antioxidants, the highest increase due to joint cultivation and/or Se supply was recorded for ascorbic acid by 1.69 times in ramson leaves and 1.48 and 1.37 times in horseradish roots and leaves, respectively. All treatments significantly increased the total antioxidant activity (AOA) of horseradish leaves (by 1.33-1.49 times) but not roots. Comparison of the results obtained in field conditions with those obtained earlier for the Se biofortification of ramson in the natural habitat (forest) revealed significantly higher levels of the plant's antioxidant status under environmental stress (field) and a decrease in the correspondent differences as a consequence of Se biofortification. The estimation of allelopathic beneficial interaction between ramson and horseradish implies the efficiency of ramson growth and production of functional food with high levels of Se (Se-ramson leaves and Se-horseradish roots).

Effects of selenium application on biochemical characteristics and biofortification level of kohlrabi (Brassica oleracea L. var. gongylodes) produce.

Background: Biofortification of vegetables with selenium (Se) greatly depends on species tolerance to Se supply. Due to the scant information regarding kohlrabi Se biofortification, the aim of the present work was the evaluation of foliar sodium selenate application on yield and biochemical characteristics of three kohlrabi cultivars. Material and methods: A two years field experiment was conducted in Moscow region (Russia) on 3 kohlrabi cultivars using foliar biofortification with Na2Se04 solutions (50, 75 and 100 mg/L) and subsequent biochemical analysis of roots, stems and leaves. Results: Out of the three concentrations tested (50, 75 and 100 mg/L) plus an untreated control, the Se 75 dose demonstrated the strongest growth stimulation effect resulting in the increase of stem weight (by 1.35-1.61 times), yield (1.37-1.66 times), monosaccharide (1.59-2.24 times), ascorbic acid (1.54-2.01 times) and total phenolic levels (by 1.23-1.37 times), compared to the untreated control. The biofortification values varied from 69.4 (White Vienna 1390) to 59.9 (Dobrynya F1 hybrid) and 43.6 (Sonata F1 hybrid) under the Se dose of 100 mg/L. The maximum Se content in kohlrabi stems reached 4.40 mg/kg d.w. for Sonata F1, 3.53 mg/kg d.w. for Dobrynya F1 hybrids and 5.20 mg/kg d.w. for cultivar White Vienna 1390. Significant correlations were revealed between Se and total phenolics (0.720; p < 0.002), ascorbic acid (0.842; p < 0.001), monosaccharides (0.898; p < 0.001) and total sugar (0.764; p < 0.001). No significant changes in nitrate levels and dry matter content were recorded as the result of Se supply. Conclusion: The outcomes of the present research demonstrated the high benefits of Se application in improving kohlrabi yield and nutritional quality.