Biochar (BC) properties and its influences within agricultural soil health and environmental ecosystems largely depend on feedstock, residence time and pyrolysis conditions. The organic and inorganic contaminants from soil can be removed using BC as an adsorbent. Additionally, soil amendment with BC is known to improve overall soil quality, microbial and enzymatic activities and soil organic carbon content with nutrient retention and availability. Moreover, one of the great impacts of BC is its capability to capture soil nutrients and sequestrate carbon. The physicochemical properties of biochar could be affected by the feedstocks and pyrolysis conditions (temperature, duration, activation method, etc.). This review paper summarizes the recent research studies on the composition of BC that controls carbon presence in soil, as well as BCs role in improving soil fertility and carbon sequestration, which has not been reported in detail yet. The main finding of the present work revealed that the high pyrolytic temperatures in BC production may have negative impacts on phyto-availability of essential nutrients. Depending on the feedstock raw material and pyrolysis process used for producing BC, it has different capacities for releasing nutrients in the soil. An economically feasible method of producing newly engineered biochar, with more controlled pyrolysis and C-based materials, for suitable agriculture needs to be developed. Further investigation should be carried out to optimize the production procedure and its application to local farming community for sustainable agriculture.

The study monitored the effect of differentiated mineral nutrition of microgreens species by solution of sodium selenate (2 mg Se/L) on the content of Se, chlorophylls, and other minerals. Chlorophylls were measured spectrophotometrically, Se by electrothermal atomic absorption method (ETAAS) with Zeeman-effect background and elements’ concentration was performed by a dual Inductively coupled plasma atomic emission spectroscopy (ICP-OES) iCAP7600 instrument. The content of selenium in fresh weight moved on average from 0.013 to 12.556 μg/g. Selenisation increased the content of Se in all tested species significantly (p < 0.05) without impacting yield. The content of chlorophyll a moved from 249.9 mg/kg (Mizuna) to 604.4 mg/kg (Arugula) with significant differences between the species, without significance (p ≤ 0.05) between tested variants. The influence of selenisation on other minerals significantly differed (p < 0.05) due to the genetic variability. A significant (p ≤ 0.05) increase in Ca was observed in green basil (10.7%) and cress (20.9%); of Fe in green basil (1.6%) and cress (40.9%); of K in arugula (1.6%), green basil (3.9%) and cress (2.8%); of Zn in arugula (2.6%), green basil (8.6%), cress (2.7%) and radish (5.9%); and of Ba in green basil (5.6%) and cress (23.9%).

The species Pleurotus ostreatus is a commercially, gastronomically, and biotechnologically important fungus. Its strain variability has been little researched. The study provides an evaluation of 59 oyster mushroom production strains in terms of the ability to accumulate selected metals in the cap and stipe. The fruiting bodies were grown under identical model conditions on straw substrate. Metal concentrations (ET-AAS) in dry fruiting bodies ranged in values 1.7–22.4 mg kg⁻¹ for Al, 2.6–9.7 mg kg⁻¹ Ba, 199–4560 mg kg⁻¹ Ca, 1.7–12.0 mg kg⁻¹ Cu, 12–120 mg kg⁻¹ Fe, 16,000–49,500 mg kg⁻¹ K, 876–2400 mg kg⁻¹ Mg, 0.39–11.0 mg kg⁻¹ Mn, 46–920 mg kg⁻¹ Na and 11–920 mg kg⁻¹ for Zn. More Cu, Fe, K, Mg, Mn, Zn accumulated in the cap, while in the stipe Ba was amassed. No significant difference was found between Al, Ca and Na between the accumulation in the cap and the stipe. Furthermore, the dependence of metal uptake from the substrate depending on the fortification of the substrate was confirmed. Statistically significant (p < 0.05) synergistic relationships were shown in pairs Al and Ba, Al and Fe, Ba and Na, Ba and Ca, Ca and Na, Cu and Fe, Fe and Mn, Fe and Zn, K and Mg, K and Mn, K and Zn, Mg and Mn, Mg and Na, Mg and Zn and Mn and Zn in the substrate without the addition of sodium selenate to the substrate. Altered relationships were observed after the application of sodium selenate to the substrate, synergism of Se and Ni, Se and Co and Se and Hg, Cu and Mn, Cu and Fe, Zn and Co, Zn and Ni, Zn and Hg, Mn and Fe, Mn and Cr, Co and Ni, Co and Hg, Ni and Hg, Pb and Cd. The findings of the study may help in the selection of production strains with hypercumulative properties for a particular metal and subsequent use in the addition of fortified fruiting bodies (e.g., with Zn). Based on the study the strains less sensitive to the accumulation of hazardous metals is possible to select for large-scale production, which is important from the perspective of food safety.

Potatoes (Solanum tuberosum L.) are an essential food for the human diet and thus represent an important source of biologically active substances. This study aimed at investigating the content of bioactive substances (total anthocyanin and polyphenol contents and chlorogenic acid) in seven potato varieties (Belana, Cecile, Magenta Love, Mozart, Talentine, Toscana, and Violet Queen) with various flesh and skin colors. To evaluate the impact of potato maturity on the analyzed parameters, potato samples were harvested in two different periods (1st harvest—July and 2nd harvest—September). Total anthocyanin and polyphenol contents were determined spectrophotometrically, and chlorogenic acid by the HPLC-DAD method. Varieties with a colored flesh (Magenta Love and Violet Queen) showed the highest content of bioactive substances. The maturity level significantly (p < 0.05) affected the total content of anthocyanins and polyphenols in potatoes. Early to medium early varieties (Belana and Magenta Love) showed an increase in chlorogenic acid content during maturation, while in other varieties, chlorogenic acid decreased due to higher maturity. In terms of the content of bioactive substances with a possible positive effect on human health, the consumption of potatoes with colored flesh could be recommended.

The objective of this paper was to examine the total polyphenols, vitamin C and capsaicin contents of pepper (varieties: Garam F1, Alma, Poseidon, Promontor, Slovakia, Claudius, Bhut Jolokia, Serrano, and Candlelight) and their correlation with the antioxidant activity by using the high performance liquid chromatography and Folin-Ciocalteu method. The limit of detection for capsaicin was 0.09 µg.g⁻¹.Vitamin C and capsaicin ranged from 95.76 to 2,139 and from 44.40 to 2,224 μg.g⁻¹ dry matter (DM), respectively. The determined total polyphenol content (TPC) ranged from 4,230 to 9,939 mg GAE.kg⁻¹ DM and the values of antioxidant activity (AA) determined by using DPPH •, FRAP and ABTS • + methods were in range 19.48–91.81, 19.08–61.46 and 15.72–65.70 μmol TE.g⁻¹ DM, respectively. Based on the statistical evaluation, there was a high correlation between vitamin C content and antioxidant activity of peppers. The obtained results suggest that due to the composition of bioactive compounds, especially antioxidants, the consumption of pepper fruits is an ideal choice for the prevention of the cell damage.

The effect of genotype and selenium foliar biofortification in the form of an aqueous solution of sodium selenate on the content of total carotenoids, vitamin C, total polyphenols and selenium content in the tomato fruits was studied. Field experiment was held in the Botanical garden of the Slovak University of Agriculture in 2016. Seven determinant varieties of tomato in the two variants were observed. The results of experiments show that treatment of plants with the dose of Se concentration (150 g Se.ha-1) at the flowering stage significantly increased the total Se content in the in tomato fruits. Foliar application of selenium had a positive effect on the increase of total polyphenol. The influence of Se biofortification on the content of vitamin C and carotenoids was not detected. Selenium foliar fertilization in dosage 150 g.ha-1 is suitable way of tomato fruits enriching in polyphenols, without negative effect on other antioxidants content.