Response of New Yellow Lupin Varieties to Inoculation with Bradyrhizobium sp. Lupinus under Central European Conditions

The aim of a two-factorial field experiment was to determine how the inoculation of seeds/soil with preparations of Bradyrhizobium sp. Lupinus (Nitragina—seed inoculation, Nitroflora I—seed inoculation, Nitroflora II—soil inoculation, HiStick® Lupin—seed inoculation) affected plant development, seed chemical composition and yield of two yellow lupin varieties (Bursztyn, Puma). This experiment was carried out with four replications in 2018 and 2019 in Poland. Precipitation during both vegetation periods was similar to or lower than the long-term mean. Average seed yield of Puma was significantly greater than Bursztyn (by 0.22 t ha−1). According to the correlation coefficients, seed yield was mainly related to plant height, dry mass of nodules per plant and mass of 1000 seeds. Our results suggest that legumes, such as lupin, should always be inoculated with Bradyrhizobium, especially if they are cultivated for the first time in a field. For optimal results, the highest-quality preparations should be used. In our study, the best results were observed after HiStick® Lupin inoculation, which resulted in the highest protein content, seed yield and protein yield across all treatments.