Plant-based fertilizers, such as liquid plant extracts, contribute to the cultivation of vegetables, particularly in organic production. The objective of this study was to determine if aqueous nettle extract could be successfully used as a fertilizer, applied on the soil and foliarly, in green bean production under field conditions. The hypothesis was that it could successfully replace mineral fertilizers and be integrated into sustainable and organic agriculture. The experiment was conducted at two climatically and pedologically different locations (Zadar and Poreč) throughout two growing seasons (spring and autumn). Two types of aqueous nettle extracts were used: a short-term extract (SE) was prepared by the extraction of wild stinging nettle (183 g 10 L⁻¹ of water) in water for 24 h, while a long-term extract (LE) was prepared at the same ratio with water extraction for 14 days. Both extracts were diluted with water at a ratio of 1:3 (extract:water) before use. The SE was applied foliarly, and LE, by pouring it onto the soil. The abovementioned treatments were compared with mineral fertilization with urea (U) and control (no fertilization (C)). Foliar fertilization with SE proved to be almost as efficient as fertilization with LE, poured onto soil, showing a positive effect on green bean vegetative parameters. Furthermore, aqueous nettle extracts showed a positive effect on the iron accumulation in the leaves.

One of the limiting factors in organic farming is the scarcity of allowed fertilizers and chemicals for plant protection. Plant and compost extracts are a promising solution for fertilization because of their positive effect on plant growth and soil microbial activity. Nettle extract was already successfully applied to some vegetables. Not-aerated nettle extract, obtained from dry nettle leaves, was applied in experiments with green beans in a quantity of 1 L per pot at two-day intervals was studied. A three-factorial experimental design was applied with two soil types (brown—Calcic Gleysol and red—Eutric Cambisol), soil disinfection with dazomet or not, and irrigated with nettle extract or water. Nettle extract application increased all above-ground traits; plant height, leaf area, flower buds, shoot dry weight at flowering, pod length, pod diameter, and shoot dry weight at harvest by 49%, 66%, 43%, 36%, 11%, 9%, and 37%, respectively, the root length at harvest by 59%, total yield by 48%, soil respiration by 91% and 74% in two soil types, and alkaline phosphatase by 30%. Dehydrogenase activity was enhanced by nettle extract application on red soil, while nettle extract application had no effect on root nodulation. The nettle extract application benefits in green bean organic production were attributed to the nutrients and other components present in the extract and not to nitrogen fixation. The optimization of the dose of the extract and experiments in real conditions of green bean production would be the next step toward the implementation of nettle extract as an organic fertilizer.

U radu se prikazuju rezultati analize hortikulturne flore kućnih vrtova Gacke doline koja je s jedne strane omeđena Velebitom, a s druge Kapelom. Istraživanje je provedeno tijekom 2018. i 2019. godine, te revidirano 2021. godine. Nasumično je izabran...

This study evaluated the effects of abiotic factors and extraction conditions on the yield, chemical composition, and antimicrobial activity of essential oil (EO) from Pistacia lentiscus L. leaves collected at four Adriatic locations during three phenological stages. Steam distillation was performed at 0.3, 0.7, and 1 bar. EO yield increased significantly with pressure, reaching a maximum at 1 bar, while the flowering stage provided the highest yields overall. Leaves from Vela Luka produced the highest EO yield, whereas Pag samples yielded the least. GC–MS analysis identified 56 components, accounting for 99.19–99.99% of total EO, with α-pinene, limonene, myrcene, and β-pinene as the dominant constituents, confirming a monoterpene-rich chemotype. All EO samples showed low but measurable inhibitory activity against Escherichia coli AB1157 and Erwinia amylovora EaED, as assessed by the disk diffusion method. Pearson correlation and PCA analyses indicated a positive association between monoterpene content and inhibition zone diameter against E. coli, and a positive association between monoterpene alcohol content and inhibition against E. amylovora. As antimicrobial activity was assessed exclusively by the disk diffusion method, the present findings may serve as an indicative basis for future investigations into the relationship between EO chemical composition and antimicrobial potential, and they require validation through quantitative, standardized antimicrobial testing.