Barley (Hordeum vulgare) grain stands out among other cereals due to its high nutritional value. It results mainly from the high content of fiber and antioxidants, such as phenolic compounds. Barley grains can also be an important source of unsaturated fatty acids and carotenoids that are beneficial to health. This study assessed the effect of the foliar application of an amino-acid biostimulant on the content of phenolic compounds, carotenoids, and the composition of fatty acids in the grain of alternative, black-grain barley genotypes, and the commonly used ‘Soldo’ cultivar, grown in conventional and organic farming systems. The dark-pigmented grains contained significantly more phenolic acids and flavonoids than the yellow seed of the traditional cultivar and were characterized by a significantly higher proportion of unsaturated fatty acids. The application of the biostimulant significantly increased the concentration of phenolic compounds in grains, especially of alternative genotypes.

The need for foods with high nutritional value has led to the rediscovery of ancient wheat species Triticum sphaerococcum and T. persicum as raw materials with valuable consumption properties, but their reintroduction requires assessment of their productivity under different agricultural practices. The field experiments were carried out for three years (2018–2020) to test the hypothesis that the sowing density of T. sphaerococcum and T. persicum (400, 500 and 600 no m⁻²) will affect their agronomic traits, yield and occurrence of diseases, but the response will depend on the hydrothermal conditions of the growing seasons. In this study, a significant correlation of the grain yield with the amount of precipitation in tillering, and from booting to the beginning of fruit development was demonstrated. The sowing density of T. sphaerococcum had an impact on the grain yield only under moderate drought stress during the growing season (2019), when the highest yield was obtained at a sowing density of 600 m⁻². In 2019, the most favorable sowing density was also the highest for T. persicum. In the year with the lowest amount of rainfall during the growing season (2018), the yield of T. persicum was the highest in the lowest sowing density. At the shooting stage, a greater intensity of powdery mildew was observed on T. persicum, especially with higher sowing densities. Increasing the sowing density also increased the occurrence of root rot symptoms in both wheat species in the year that favored the occurrence of this disease (2018). It can be concluded that in the integrated low-input cultivation of T. sphaerococcum and T. persicum, it is justified to use a sowing density of 600 pcs. m⁻², in an agroclimatic zone with moderate droughts during the growing season.

Beneficial dietary and pro-health values, have resulted in the increasing consumption importance of barley. Therefore, genotypes and cultivation methods are sought that guarantee high functional value of grain. The aim of the study was to assess the content of phenolic acids, flavonoids, chlorophylls, anthocyanidins, phytomelanin and antioxidant activity of grain of three barley genotypes depending on agricultural technology. Two of them are primary genotypes with dark grain pigmentation Hordeum vulgare L. var nigricans and H. vulgare L. var. rimpaui, the third is a modern cultivar ’Soldo’ H. vulgare with yellow grain, which is the control sample. Evaluated the effect of foliar application of a amino-acids biostimulant on the functional properties of grain under the conditions of organically and conventionally cultivations. The results indicated a higher antioxidant activity and the concentration of phenolic acids, flavonoids and phytomelanin in the black-grain genotypes. Organic cultivation and application of amino acids had increased the content of phenolic compounds in grain. The antioxidant activity was correlated with the content of syringic acid, naringenin, quercetin, luteolin and phytomelanin. Organically cultivation and the foliar application of an amino acid biostimulant improved the functional properties of barley grain, in particular the original, black-grained genotypes.

Alternative barley genotypes can be a source of genetic variability for breeding and raw material for functional food production. The reaction of these genotypes to diverse sowing densities is unknown. The study aimed to assess the response in physiological characteristics of alternative barley genotypes Hordeum vulgare var. rimpaui and H. v. var. nigricans to increasing sowing density. In a strict field experiment, two barley genotypes and five sowing densities were tested: 250, 300, 350, 400, and 450 grains m^-2. Chlorophyll fluorescence indices, relative chlorophyll content (SPAD), and leaf area index (LAI) were assessed. The interaction of the study year, genotype, and sowing density significantly shaped the physiological indices of the canopy. When rainfall was deficient, the plants reduced their leaf area but had higher SPAD and PI_abs of the flag leaf. In the year with optimal rainfall, LAI increased with increasing sowing density. In the dry year, PI_abs of the flag leaf in H. v. var. rimpaui was the highest at 250 grains m^-2 and decreased with increasing density, and in H. v. var. nigricans, it only reduced at 450 grains m^-2 A strong negative relationship was observed between LAI and SPAD, as well as between LAI and PI_abs. Sowing density had a significant effect on grain yield per plant, which was related to the physiological response. However, the genotypes tested responded differently to this factor. The results may by prove for agricultural practice and scientific research, particularly in relation to the optimal sowing density of alternative barley genotypes and the identification of density-tolerant genotypes in response to varying environmental conditions.

Nitrogen fertilization may affect the functioning of photosynthesis as well as the chemical composition and antioxidant potential of cereal grains. Little is known about the relationship between the efficiency of photosynthesis and the content of phenolic compounds in barley grain, especially in conditions of varying nitrogen availability. In this regard, a field experiment was conducted to examine the responses of two primary barley genotypes with elevated phenolic compound content (TPC) in grain and an intensive modern cultivar H. v. vulgare with high protein content to increasing nitrogen fertilization (rates of 0, 30, 60 and 90 kg N ha⁻¹) during the study years, which differed in terms of hydrothermal conditions. The leaf greenness index (SPAD) and chlorophyll fluorescence parameters were evaluated on three occasions throughout the growing season. Following the harvest, the chemical composition of the grains, including phenolic acids, flavonoids and antioxidant potential, was evaluated. The antioxidant potential and chemical composition of the grain, including TPC and protein content, depended to the greatest extent on genetic and environmental factors, and only then on nitrogen fertilization. Nitrogen increased the TPC content and antioxidant capacity ABTS⁺ of the grains of all studied genotypes and the protein content in H. v. vulgare grain. Rates of 60 and 90 kg N ha⁻¹ resulted in a significant increase in the SPAD, PI_abs and F_v/F_m in BBCH 34 and 57. A positive correlation was confirmed between the SPAD and PI_abs and the content of TPC and ABTS⁺ in the grain. The dependence of qualitative characteristics on the F_v/F_m was also demonstrated. The primary genotypes are characterized by a greater genetic potential for the synthesis of phenolic compounds than the modern cultivar H. v. vulgare. The synthesis of phenolic compounds, and thus their accumulation in the grain, is clearly stimulated by unfavorable environmental factors and moderate nitrogen rates and depends on the chlorophyll content in the leaves and the efficiency of photosynthesis. N fertilization has a beneficial effect on the content of phenolic compounds in grain resulting from the improvement in the SPAD and PI_abs. The chemical composition of grain and the increase in antioxidant potential are determined by the F_v/F_m, which is low under hydrothermal stress conditions.

Black-seeded barley can be a valuable raw material for functional food. However, its restoration to cropping should be preceded by the identification of the characteristics determining productivity. The field study was conducted to identify specific parameters of the black-seeded barley genotypes (Hordeum vulgare var. nigricans and H. v. var. rimpaui) and compare them with common barley (H. vulgare) under the different hydrothermal conditions of the two growing seasons of 2021 and 2022. Our research has shown that each genotype has a set of specific characteristics that best describe it at a given developmental stage. H. v. rimpaui was well characterized by chlorophyll fluorescence parameters such as F_V/F_M, F_V/F₀, and PI_ABS at the seedling stage and H. v. nigricans by F_V/F_M and F_V/F₀ at the flag leaf stage. Moreover, H. v. var. rimpaui was distinguished by a high biomass of shoot (726 g m⁻²) and straw yield (5.04 t ha⁻¹) but H. v. var. nigricans by a high number of sterile generative tillers (103 m⁻² in the dry year 2022). Further research should focus on the response of black-seeded barley genotypes to abiotic stresses, while in agronomic practice, efforts should be made to increase the number of grains per ear and 1000-grain weight.