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Research on strawberry (Fragaria x ananassa Duch.) was carried out in greenhouse in 2022-2023, arranging a 4 x 2 factorial experiment, consisting of four levels of electrical conductivity of the nutrient solutions (1.2, 1.7, 2.2, and 2.7 dS m-1) and application of gypsum (without application – control and application). The plants were grown in coconut fibre substrate from late October to early June. The 2.2 dS m-1 ECsol resulted in the highest yield, whereas the highest values of dry matter and soluble solids were recorded under 2.7 dS m-1 ECsol. Gypsum application resulted in the increase of dry matter, soluble solids, firmness and colour components. The 2.2 and 2.7 dS m-1 ECsol led to the highest levels of hydrophilic and lipophilic antioxidant activities as well as polyphenols and vitamin C. From the research carried out on strawberry grown in coconut fibre, it arose that the 2.2 dS m-1 EC of the nutrient solution showed the best effect on yield, but it did not generally differ from 2.7 dS m-1 regarding the quality of the 'fruits'. Gypsum treatment represents an effective strategy to improve some important qualitative characteristics of strawberry 'fruits', under the perspective of sustainable management of crop systems.

Recent agricultural research has prioritized the development of environmentally friendly management strategies to ensure food security, among which the application of biostimulants such as brown algae extracts, arbuscular mycorrhizal fungi (AMF), and their combination are included. The experimental protocol was based on the factorial combination of two planting times (4 May and 1 June) and seven biostimulant treatments (three brown algae species, Cystoseria tamariscifolia—C.t.; Fucus vesiculosus—F.v.; Padina pavonica—P.p.; arbuscular mycorrhizal fungi—AMF; C.t. + AMF; F.v. + AMF; P.p. + AMF) plus an untreated control. The earlier transplant resulted in a higher yield, due to the higher number of fruits per plant, and a higher plant fresh and dry biomass. The treatments with P.p. and F.v. extracts and the combination P.p. + AMF led to the highest yields (56.7 t ha−1), mainly due to the highest fruit number per plant. The earlier planting time led to higher values of dry residue, soluble solids, firmness, and colour component ‘a’. The highest values of fruit dry residue were recorded under the F.v. and P.p. extracts, and the combinations F.v. + AMF and P.p. + AMF, the highest soluble solid content with P.p. treatment, and firmness under P.p. + AMF. The highest levels of ‘L’ and ‘a’ fruit colour components were obtained under the P.p. extract treatment, of ‘b’ upon the application of P.p. and F.v. extract, and AMF + P.p. and AMF + F.v. The later planting time led to significantly higher values of the antioxidant parameters, as did the application of the P.p. extract and P.p. + AMF. CAT activity was more intense corresponding to the later tomato crop cycle, P.p. extract, and AMF + P.p. Overall, our study highlights the potential of biostimulants, particularly brown algae extracts and their combination with AMF, to improve tomato yield, antioxidant properties, and biochemical activities.

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.