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.

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.

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.

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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The aim of experiments was to assess the efficiency of choline-stabilized orthosilicic acid (ch-OSA; complex of orthosilicic acid with choline and a bioavailable source of silicon) application under increasing manganese (Mn) stress on the micronutritional composition and yielding of tomato (Solanum lycopersicum L. cvs. 'Alboney F1' and 'Emotion F1'). Plants were grown in rockwool with the application of a nutrient solution varied the Mn concentrations (in mg dm(-3)): 9.6 and 19.2 which cause strong oxidative stress of plants comparing with optimal concentration of that microelement in nutrient solution. The effect of ch-OSA application (at Si concentration of 0.3 mg dm(-3) nutrient solution) was investigated at both Mn-levels. Increasing Mn stress modified the concentration of microelements and silicon (Si) in tomato leaves. Application of ch-OSA also influenced the concentration of nutrients, but the determined changes were generally multidirectional and varied depending on Mn-level and cultivar. Under the increasing Mn stress a significant downward trend was observed for the mean concentration of Fe (in both cultivars) in fruits--but changes of Mn, Zn and Cu were varied depend on cultivar. In the case of cv. 'Alboney F1' ch-OSA application caused an increase the mean concentrations of Fe, Zn and Cu, while in the case of cv. 'Emotion F1' the reduction of mean concentrations of Zn and Cu was recorded. Ch-OSA treatment did not influence on the Mn concentrations in fruits. A beneficial role of ch-OSA was also found in photosynthesis activity. This was especially valid for lower levels of Mn. Application of ch-OSA improved significantly the marketable yield of tomato under stress by a low Mn level.

Abstract:The last two decades have brought a signifi cant modernization in methods of cultivation in greenhouses. Soilless cultures, isolated from soils, have become a common practice, similarly as fertigation (fertilization + irrigation) installations, although most of them are applied in the open system (with no recirculation), where excess nutrient solution is removed straight to soil. This situation was the reason why it was decided to conduct studies, extended over a period of many years, on the estimation of environmental pollution caused by discharged drainage waters containing mineral fertilizers in economically important cultures in Poland (anthurium, tomato, cucumber). On the basis of the chemical composition of drainage waters and amounts of nutrient solution spillway from culture beds data were estimated concerning pollution of the soil medium by the nutrient solution. The level of pollution was dependent on nutrient requirements of crops and the length of the vegetation period. The highest environmental pollution is caused by intensive tomato growing (in kg·month·ha -1 ): N-NO 3 (up to 245), K (up to 402), Ca (up to 145) and S-SO 4 (up to 102). A lesser threat is posed by metal microelements: Fe (up to 2.69), Mn (up to 0.19), Zn (up to 0.52) and Cu (up to 0.09). Lower contamination of the natural environment is generated in cultures with lower nutrient requirements (anthurium) and in the case of culture on organic substrates. With an increase in ecological awareness of producers recirculation systems should be implemented in the production practice, in which drainage waters do not migrate directly to soil, but are repeatedly used to feed crops.

A way to alleviate excessive Mn nutrition of plants is through silicon application. The aim of the present study was to examine the effect of different Si concentrations in a nutrient solution and Si plant spraying treatments (in the form of silica sol) on the yielding and nutritional status of hydroponically grown lettuce under Mn-stress. The experiments were conducted under controlled conditions in a phytotron. The influence of the following Si levels in the nutrient solution (5.5-control; 15.5; 23.25 and 31 mg Si dm-3) and foliar sprays (distilled water; Si solution) were investigated. Silicon supplied through fertigation significantly affected the plant's nutrient status and alleviated the Mn stress, increasing fresh matter production, RWC (Relative Water Content) and the number of leaves per plants, while decreasing the share of dry matter. The Si nutrition did not change the content of Mn in the leaves, but caused a significant increase in N, P, Na, Fe and Si concentrations with a simultaneous decrease of Zn and Cu levels. The content of Ca, Mg and K was relatively stable (except for the treatment with the most intensive Si nutrition). Generally, the concentrations of N, P, K, Ca, Mg, Na and Fe within the tested Si range were higher than in the control, while being lower in the case of Zn and Cu. Overall, the foliar application of Si did not change plant yielding, the number of leaves on plants and most macro-and microelement concentration in leaves, but modified significantly the RWC as well as the Cu and Na content. The dry matter content under Si nutrition was varied. In summary, an effective method to alleviate Mn-stress is to apply silica sol to a nutrient solution used for plant fertigation.