Non-Aerated Common Nettle (Urtica dioica L.) Extract Enhances Green Beans (Phaseolus vulgaris L.) Growth and Soil Enzyme Activity.

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.

Determination of the Variability of Biophenols and Mineral Nutrients in Olive Leaves with Respect to Cultivar, Collection Period and Geographical Location for Their Targeted and Well-Timed Exploitation.

The interactive effects of cultivar, collecting period, and geographical location on the content and composition of biophenols and macro and micronutrients in olive (Olea europaea L.) leaf were investigated. Leaves of six cultivars were collected at three periods in two locations in Croatia. The leaves of Istarska bjelica cultivar had the greatest biophenol (oleuropein) potential, especially those sampled in January and in March at the location of Pag. All the cultivars yielded leaves with the highest concentration of biophenols in March, which coincided with the pruning period. Except for high oleuropein concentration in Istarska bjelica, flavonoids were found to be most useful for differentiating olive leaves according to cultivar. Verbascoside turned out to be the most potent differentiator of collecting periods, while phosphorus and zinc turned out to be most useful for differentiating locations. Despite different agroecological conditions at the two locations, cultivar exhibited a significant effect on olive leaf nutrient composition, which was certainly causally related to that of the biophenols. The results obtained showed that it is possible to plan more well-timed and efficient exploitation of biophenols from olive leaf based on the knowledge about the interactive effects of the three studied factors.

Temporal Variation of Phenolic and Mineral Composition in Olive Leaves Is Cultivar Dependent.

In order to investigate the potential of various olive cultivars and leaf sampling times for phytochemical farming practice in Croatia, phenolic and mineral composition was determined in olive leaves of four Croatian cultivars and Italian cultivar Leccino collected at three occasions, in October 2017, January 2018, and March 2018. Istarska bjelica turned out to have the largest phytochemical potential among the investigated cultivars due to steady high oleuropein concentrations found in its leaves. The concentration of main phenolic components in Istarska bjelica leaves changed only slightly during the sampling period, suggesting the possibility of its higher capability for low air temperatures stress resistance and different metabolic response compared to the other studied cultivars. Low air temperatures increased the oleuropein level and antioxidant activity in leaves of Leccino, Oblica, Levantinka, and Drobnica cultivars, which may be of crucial phytochemical farming interest. Each of the investigated olive cultivars was characterized by a specific leaf mineral nutrient composition, which could have had a specific role in their interplay with phenols.

Biogenic amines in selected foods of animal origin obtained from the Croatian retail market.

This study aimed to investigate the presence of eight biogenic amines (BAs): tryptamine (TRP), phenylethylamine (PHE), putrescine (PUT), cadaverine (CAD), histamine (HIS), tyramine (TYR), spermidine (SPD) and spermine (SPM) in cheese, fish & fishery products and meat & meat products obtained from the Croatian retail market. A selective and robust method of high-performance liquid chromatography (HPLC) with diode array detection (DAD) was applied for the determination of BAs in a total of 91 samples in accordance with the performance criteria outlined in the European legislation. A high inter- and intra-food group variability of the amounts of BAs was observed. In the analysed samples, the most represented amines were TYR, HIS, CAD and PUT. Based on the highest content of the most toxic BAs (HIS and TYR) and consequential food safety concerns, the studied food groups can be ranked in the following order: cheese (HIS up to 106.4 mg/kg; TYR up to 206.6 mg/kg), fish &fishery products (HIS up to 98.8 mg/kg; TYR up to 47.9 mg/kg), and meat & meat products (HIS up to 20.0 mg/kg; TYR up to 117.5 mg/kg). The total BA content was significantly higher (p < .05) in fermented in comparison with other food. The study aimed to contribute to the knowledge on BA toxicity and food quality, as well as to support the indispensable future studies of consumption data and exposure assessment, to the end of defining allowable BA concentrations in food.

Flow injection spectrophotometric determination of N-acetyl-L-cysteine as a complex with palladium(II).

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd(2+) ions in the concentration range from 1.0 × 10(-5) mol L(-1) to 6.0 × 10(-5) mol L(-1). The detection limit NAC was 5.84 × 10(-6) mol L(-1) and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd(2+) form complexes of Pd(2+):NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)(2)(2+) complex is ß(12)' = 2.69 × 10(9) L(2) mol(-2). The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl(2), and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.