The influence of seed inoculation with a bio-preparation of nodule bacteria Rhizobium leguminosarum, fertilization of 0, 40, 80, 120 kg N/ha and molybdenum topdressing on the yield of green mass, dry ma�er, seed, average number of pods per plant, average number of seeds per pod, average nodule number per plant, nodule dry weight as well as plant and seed protein concentration were studied during the two years of investigations on two soils -Mollic Gleysols and Eutric Cambisols. The highest values of all investigated parameters were obtained in the inoculated seed variants with molybdenum application, except the average nodule number per plant where the highest values were achieved in variants without molybdenum. The effect of nitrogen fertilization depended on the soil type, i.e. its chemical properties. The largest number of the investigated parameters obtained the highest values as a result of fertilization with 40 kg N/ha on Mollic Gleysols (3.96% humus). Thus, seed yield was 4.02 t/ha, nodule dry ma�er 0.482 g per plant whereas seed protein concentration was 26.91%. The largest number of the investigated parameters on Eutric Cambisols (1.07% humus) obtained the highest values with fertilization of 80 kg N/ha where seed yield amounted to 3.65 t/ha, nodule dry ma�er 0.456 g per plant while seed protein concentration was 26.48%.

In an 18‐week treatment, the effect of linolenic acid on European catfish (Silurus glanis L.) growth indicators was investigated as to weight gain, feeding coefficient (FCR value), specific growth rate (SGR value), protein efficiency ratio (PER value), productive protein value (PPV) and survival rate. Concurrently, the fishmeat chemical composition was also investigated. The experiment was organized into four groups, each divided into three subgroups. Stocked in each of 12 cages were 30 × 1‐year‐old catfish, with individual weights ranging from 148.5 to 151.5 g/ind. All fish were given standard feed for European catfish which contained 45% protein. The first batch, control group (C), received no additional linolenic acid. Linolenic acid was added to the feed of the second (E1), third (E2) and fourth group (E3), at 0.5, 1.0 and 1.5%, respectively. Growth indicator improvement was best in the E2 group fed the 1% linolenic acid, whereby the fish weight gain was 12.6% higher and the feeding coefficient 12.9% lower, while SGR, PER and PPV values were 6.1, 12.0 and 15.8% better than the control group. Growth indicators were also significantly (P < 0.01) improved in the three groups receiving additional linolenic acid in comparison to the control group. Moreover, this addition positively affected fishmeat quality by increasing meat protein content from 18.04% (C) to 18.79% (E3). The total unsaturated fatty acid content also increased from 65.07% (C) to 69.82% (E3), and the total saturated fatty acid content decreased from 31.36% (C) to 26.50% (E3); consequently, the ratio of unsaturated to saturated fatty acids increased from 2.07% (C) to 2.63% (E3). It can be concluded that the addition of 1% linolenic acid to standard catfish feed has beneficial effects on fish growth indicators and meat quality.

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