Phytohormones are chemical substances that regulate plants growth, reproductive processes, longevity, development, and even death. One of the most common representatives of this group is indole-3-butyric acid (IBA), which is widely applied in various branches of agriculture. Taking into consideration that the conversion of conventional herbicides into ionic liquids leads to the enhancement of their biological activity, we decided to implement the same strategy for selected phytohormone. Hence, we synthesized a homologous series comprising alkylated choline cations and indole-3-butyrate anions. The new biobased ionic liquids (ILs) were characterized in terms of physicochemical properties (thermal stability, phase transitions, solubility, surface activity, density, and viscosity) and susceptibility to biodegradation according to the OECD 301 F test. Subsequently, their activity as a growth stimulator was evaluated for butterhead lettuce (Lactuca sativa L.) as a test plant. Additionally, the nutrient assimilation by the test plants was analyzed. The study revealed that the IL containing cations with octyl groups, at the optimal concentration of 0.5 ppm, enhanced lettuce biomass production by approximately 21% compared to that of the control. Moreover, the lettuce was enriched with valuable micro- and macroelements, such as P, K, Ca, Mg, Na, and Mn. These findings comply well with the concept of sustainable agriculture focused on utilizing environmentally friendly compounds derived from sources of natural origin while exhibiting enhanced efficacy.

Magnesium (Mg) serves specific physiological functions in plants, as it participates in 250÷400 processes and may not be replaced by other elements, even those exhibiting similar physicochemical properties, such as Co 2+ , Mn 2+ or Ni 2+ . The aim of the conducted studies was to optimize magnesium nutrition of onion (Allium cepa L.), through the evaluation of yielding of plants, and to determine its effect on contents of the following elements in leaves and bulbs: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Magnesium was applied in the quick-acting form, MgSO4·7H2O, based on the chemical analyses of soil, in doses corresponding to 50, 100, 150 and 200 mg Mg·dm -3 soil. The other nutrients were supplemented to standard levels recommended for the cultivation of onion, amounting to (in mg·dm -3 soil) 150 N, 80 P and 200 K. Magnesium nutrition was found to have a positive effect on yielding of onion and its quality. Significantly the highest total yield (4.85 kg·m -2 ) and merchantable yield (4.78 kg·m -2 ) were obtained when applying Mg-100, which amounted to an increase by 38% and 45% in comparison with the control combination. Plant nutrition with magnesium in case of leaves significantly affected an improvement of their nutrient status for nitrogen, deterioration of calcium nutrition, while in case of leaves and bulbs that of potassium. Analyzed levels of magnesium nutrition had a significant effect on nutrient status of leaves and bulbs for this nutrient. Leaves accumulated more nitrogen, potassium, calcium and magnesium than bulbs. Controlled magnesium nutrition of plants is an effective method of biofortification of onion with this nutrient.

This study evaluated the effect of increasing manganese (Mn) nutrition on the content of antioxidative compounds such as vitamin C, lycopene and polyphenols, and the antioxidant activity of tomato (Lycopersicon esculentum Mill., cvs 'Alboney F1' and 'Emotion F') fruit. Plants were grown in rockwool using a nutrient solution with the following content of Mn (mg dm): 0.0, 0.3, 0.6, 1.2, 2.4, 4.8, 9.6 and 19.2. The level of vitamin C and lycopene decreased with the increasing Mn nutrition. Since the colour of fruits was correlated with the change in carotenoid content, the decrease in lycopene content promoted the reduction of redness and increase of yellowness of fruits. However, total polyphenol content and antioxidant activity significantly increased when plant were exposed to toxic levels of Mn. Observed changes could be the result of the oxidative stress induced by high concentrations of Mn. Polyphenolic compounds play a crucial role in the plant's response to Mn stress and affect predominantly the total antioxidant properties of fruits, which could be used as a source of phenolics. Moreover, total phenolic content measurement, as an easy and inexpensive method, could be used as an indicator of Mn-induced stress in fruits of tomato.

A b s t r a c tThe main aim of the present study was to evaluate the influence of the chemical composition of a nutrient solution (NS I, NS II), seed inoculation with Effective Microorganisms (EM), and assimilation illumination (AI) of plants on the growth, development and nutritional status of lettuce (Lactuca sativa L.) in hydroponic cultivation and microbiological changes in the medium. The measurements were as follows: quantity of leaves per plant (LQ), surface area of the biggest leaves of plants (SBL), relative chlorophyll content (SPAD units), total fresh weight (TFW), total dry weight (TDW), percentage (%) of dry matter (% DM), chemical composition of leaves, nutrient uptake (N, P, K, Ca, Mg, Na) of the aboveground parts of the plant. It was shown that the simultaneous inoculation of seeds with EM and application of NS II had an effect on improving seed germination (1 st -5 th day after sowing), but a significantly positive influence of NS I on seed germination was found from the 5 th to 9 th day. The application of NS II and EM-A had a positive influence on the development of leaves on the plant. The chemical composition of the nutrient solution was found to have a significant effect on the biometrical parameters of plants. The use of supplemental lighting in cultivation of lettuce affected positively both the growth and development of plants. The chemical composition of the nutrient solution significantly modified the macronutrient nutrition status of plants, while the illumination of plants only in case of phosphorus -but at the same time it had a significant influence on the uptake of all nutrients by the plant. The influence of EM was not proved. The microbiological analysis showed a significant influence of the chemical composition of nutrient solutions on the changes in the numbers of the analyzed groups of microorganisms, showing an increase in their numbers in nutrient solutions with higher contents of chemical elements. However, there were no significant changes in the number of microorganisms relative to the treatment with assimilation illumination and to that of seed inoculation with EM solutions.

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