Soil salinity is an important environmental factor affecting physiological processes in plants. It is possible to limit the negative effects of salt through the exogenous application of microelements. Silicon (Si) is widely recognized as an element improving plant resistance to abiotic and biotic stresses. The aim of the research was to determine the impact of foliar application of Si on the photosynthetic apparatus, gas exchange and DNA methylation of barley (Hordeum vulgare L.) grown under salt stress. Plants grown under controlled pot experiment were exposed to sodium chloride (NaCl) in the soil at a concentration of 200 mM, and two foliar applications of Si were made at three concentrations (0.05%, 0.1% and 0.2%). Measurements were made of relative chlorophyll content in leaves (CCl), gas exchange parameters (C_i, E, g_s, and P_N), and selected chlorophyll fluorescence parameters (F_v/F_m, F_v/F₀, PI and RC/ABS). Additionally, DNA methylation level based on cytosine methylation within the 3′CCGG 5′ sequence was analyzed. Salinity had a negative effect on the values of the parameters examined. Exogenous application of Si by spraying leaves increased the values of the measured parameters in plants. Plants treated with NaCl in combination with the moderate (0.1%) and highest (0.2%) dose of Si indicated the lowest methylation level. Decrease of methylation implicated with activation of gene expression resulted in better physiological parameters observed in this group of barley plants.

Oat (Avena sativa L.) is one of the agricultural crops that can be grown in marginal areas. Grain and straw are used mainly for food and fodder purposes. However, due to the high-fat content in the grain and the small amount of ash, it can be an attractive raw material for energy production. The biomass can be straw and oat grain. Grain should be intended for food purposes, but if it does not meet the quality requirements, it can be used for energy purposes. The aim of the experiment was to evaluate the energy usefulness of four oat cultivars depending on the applied level of nitrogen fertilization. The research results show that oat grain and straw can be used as fuel for energy purposes. The average calorific value of grain was 18.7 MJ·kg⁻¹, and the ash content in dry matter was 2.03%. With the increase in the dose of nitrogen fertilization, a decrease in the calorific value of oat and straw grains and a decrease in ash content were noted. The findings show significant varietal differences. Oat straw had a lower calorific value and a higher ash content, which indicates its lower usefulness for energy purposes compared to grain.

Environmental conditions are the primary factor determining the growth and yield of plants. As a result of climate change, the negative impact of abiotic factors is intensifying. One of them is salt stress. Soil salinity is one of the major problems in agriculture in the world and affects many cultivar species. The aim of this study was to evaluate the effect of silicon foliar application on the physiological and epigenetic reaction of oats (Avena sativa L.) under salt stress. The pot experiment was carried out in controlled conditions. Oat plants were subject to sodium chloride (NaCl) at a concentration of 200 mM and applied to the soil. Three concentrations of Optysil (200 g∙L⁻¹ SiO₂) were used for foliar fertilization. Measurements were made of the relative chlorophyll content in the leaves, the selected chlorophyll fluorescence parameters, and the gas exchange parameters. In this study, methylation-sensitive amplification polymorphisms (MSAP) analysis was used to investigate the effect of Si application during salinity stress on the DNA methylation level in oat plants. The results of this study indicated that the exogenous application of silicon improved the tolerance of the oat plants to salinity. The doses of 0.1% and 0.2% Optysil had the greatest effect on alleviating the impact of salt stress on the oat plants. In this research, the epigenetic as well as the physiological response of plants to the applied experimental factors were analyzed, which is a broad coverage of the research topic on the effects of salinity and silicon on plants.

Soil salinity is considered a serious problem that limits agricultural productivity. Currently, solutions are being sought to mitigate the negative impact of salt on economically important crops. The aim of the study was to evaluate the effect of foliar application of silicon (Si) on the physiological and epigenetic responses of wheat grown under salt stress conditions. The experiment with wheat seedlings was established in pots with 200 mM NaCl added. After 7 days, foliar fertilizer (200 g L⁻¹ SiO₂) was used at concentrations of 0.05, 0.1 and 0.2%. Physiological parameters were measured three times. The addition of salt caused a significant decrease in the values of the measured parameters in plants of all variants. In plants sprayed with Si fertilizer under salinity conditions, a significant increase in CCI and selected gas exchange parameters (P_N, C_i, E, g_s) and chlorophyll fluorescence (PI, RC/ABS, F_V/F_m, Fv/F₀) was observed. Si doses of 0.1 and 0.2% showed a better mitigating effect compared to the dose of 0.05%. The observed effect was maintained over time. The results obtained indicate a positive role for foliar silicon fertilization in mitigating salinity stress in wheat. Epigenetic mechanisms play an important role in regulating gene expression in response to stress. Changes in the status of methylation of the 5′CCGG3′ sequence of the nuclear genome of wheat plants exposed to salinity and treated with Si at different doses were determined by the MSAP approach. The obtained results showed a clear alteration of DNA methylation in plants as a response to experimental factors. The methylation changes were silicon dose-dependent. These modifications may suggest a mechanism for plant adaptation under salt stress after silicon application.

Soil salinity is one of the most important environmental factors threatening agriculture on a global level. Plants show differences in resistance to salt stress, both in terms of species and variety. The aim of the study was to determine the effect of salt stress on photosynthetic efficiency and the activity of plants of two barley varietie—KWS Irina and RGT Planet. Plants grown in a pot experiment were subjected to soil treatment with sodium chloride (NaCl) at concentrations of 0, 50, 100, and 150 mmol∙(dm³)⁻¹. Measurements were made four times at intervals of 7, 14, 21, and 28 days after the application of NaCl. The relative chlorophyll content in leaves (CCl) and selected chlorophyll fluorescence parameters (F_v/F_m, F_v/F₀, and PI) and gas exchange parameters (P_N, E, g_s, and C_i) were assessed. In the final stage of the experiment, a visual assessment of the plants’ condition was carried out and the amount of fresh mass (FM) of the above-ground part was determined. The content of sodium and potassium in the vegetative parts of plants was also analysed. Salinity significantly influenced the values of the measured parameters in both of the tested barley genotypes. High salt concentrations in the soil at levels of 100 and 150 mmol NaCl (dm³)⁻¹ negatively affected the growth and development of plants by disturbing the process of photosynthesis and other plant gas exchange parameters. The antagonistic effect of sodium in relation to potassium resulted in a decrease in the K⁺ content in the plants, along with an increase in the salinity level.

Barley is an economically important plant cultivated primarily for animal feed and in the brewing industry for the production of barley malt. Climate changes and an increase in grain demand result in a constant need to improve the volume and stability of cereal species yields and better use the potential of cultivars. In cereal production, an important aspect is the use of microelements, especially by foliar spraying. Microelements, as components or enzyme activators, play a significant role in plant growth and metabolic processes occurring in the cell. As a consequence, their availability is a factor determining plant development. The aim of this study was to determine the effect of foliar fertilization with selected microelements on the yield of two-row malting barley cultivars. In 2019–2021, a two-factor field experiment with barley was conducted in south-eastern Poland. The experimental factors were three spring barley cultivars (Baryłka, KWS Irina, and RGT Planet) of the brewing type and four single-component micronutrient fertilizers containing copper (Cu), manganese (Mn), molybdenum (Mo), and zinc (Zn). The foliar application of microelements resulted in improvements in selected elements of the yield structure and an increase in grain yield, and the effect depended on the fertilization applied. The highest grain yield was obtained from plots where fertilizer with Mo or Zn was used. Barley plants sprayed with Mo fertilizer developed the longest spikes and were characterized by the highest number of productive tillers per plant. The foliar application of Zn resulted in the formation of the highest number of spikes per unit area and grain uniformity. The RGT Planet cultivar was characterized by higher values of the measured parameters compared to Baryłka and KWS Irina.