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Silicon as a Predicator of Sustainable Nutrient Management in Maize Cultivation (Zea mays L.)
Field trials were conducted at the Field Experimental Station in Winna Góra. Weed control after maize sowing increased the grain yield by 15.7% compared to that after herbicide application at the BBCH 14/15 stage. Higher effectiveness of silicon application in maize cultivation can be achieved on plantations free from primary or secondary weed infestation. The application of a 50% NPK dose increased the grain yield by 8.6%, while a 100% dose improved it by 13.9% compared to that of the control object (without mineral fertilization). Furthermore, it was observed that the effectiveness of the silicon increased with higher total precipitation during the maize growing season, as evidenced by the results from 2022. In that year, the difference between the control (without silicon application) and the treatment with silicon applied at the BBCH 15/16 stage was more than 33%. The average mass losses from the green tea bags ranged from 54.9% to 71.9% in the variant of the sowing experiment carried out after spraying with the herbicide and from 69.4% to 72.4% in the variant with herbicide spraying at the BBCH14 stage. The rooibos tea’s mass losses were lower, as expected, and ranged from 18.6% to 36.4% in the first variant and from 30.8% to 38.6% in the second variant. The mass losses of the green tea and rooibos tea were the highest in the variant with herbicide spraying at the BBCH14 stage and the lowest in the variant of the sowing experiment carried out after herbicide spraying. The stabilization factor (S) ranged from 193 × 10−3 to 254 × 10−3 in sowing after herbicide spraying and from 188 × 10−3 to 226 × 10−3 in the variant with herbicide spraying at the BBCH14 stage. The k (decomposition constant) ranged from 7.8 × 10−3 to 11.5 × 10−3 in the first variant and from 7.2 × 10−3 to 13.4 × 10−3 in the variant with herbicide spraying at BBCH14.
Natural Deep Eutectic Solvents Combined with Supercritical Carbon Dioxide for the Extraction of Curcuminoids from Turmeric
Background: Curcuminoids, the bioactive compounds found in turmeric, exhibit potent antioxidant, anti-inflammatory, and neuroprotective properties. This study aims to enhance the extraction of curcuminoids from turmeric using environmentally friendly solvents supercritical CO2 (scCO2) combined with natural deep eutectic solvents (NADESs) in one process, and to evaluate the resulting biological activity. Methods: A Box–Behnken statistical design was applied to optimize scCO2 extraction conditions—pressure, CO2 volume, and temperature—to maximize curcuminoid yield. Next, the menthol and lactic acid NADESs were selected, and these two solvents were combined into a single turmeric extraction process. The biological activity of the resulting extract was evaluated using antioxidant assays (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl) and enzyme inhibition assays (acetylcholinesterase, butyrylcholinesterase, and tyrosinase). Toxicity assessments were conducted on the aquatic invertebrates Daphnia pulex, Artemia sp., and Chironomus aprilinus. Results: The most effective extraction was achieved using a menthol–lactic acid NADES as a cosolvent, integrated at a 1:20 ratio of plant material to NADESs while in combination with scCO2. The optimized scCO2–NADES extraction resulted in a high curcuminoid yield (33.35 mg/g), outperforming scCO2 extraction (234.3 μg/g), NADESs ultrasound-assisted extraction (30.50 mg/g), and alcohol-based solvents (22.95–26.42 mg/g). In biological assays, the extract demonstrated significant antioxidant activity and effective inhibition of enzymes (acetylcholinesterase, butyrylcholinesterase, and tyrosinase). Toxicity studies showed a concentration-dependent response, with EC50 for Chironomus aprilinus at the level of 0.098 μL/mL and Daphnia pulex exhibiting high sensitivity to the extract. Conclusions: This study highlights the potential of combining NADESs and scCO2 extraction in one process, demonstrating the effectiveness of scCO2–NADES extraction in maximizing curcuminoid yield and enhancing bioactivity.