Impact of Rhizobial and Mycorrhizal Inoculation on Alfalfa Cultivars Productivity under Different Liming Levels

Alfalfa (Medicago sativa L.) is a highly valuable crop in agriculture, particularly due to its high biomass yield, rich protein content, and excellent digestibility, making it essential for livestock farming. However, its sensitivity to acidic soils presents a significant challenge for establishing and cultivating alfalfa in degraded soils. The current study aim was to investigate how selected inoculants affect alfalfa production when applied to acidic soils with different levels of liming. In this study, the effects of pre-sowing seed inoculation treatments of rhizobia - Sinorhizobium (Ensifer) meliloti (R), mycorrhizal fungi (MF), co-inoculation of rhizobia and mycorrhizal fungi (RMF), and control-no inoculation (C) -were assessed in three alfalfa cultivars (K-28, Zuzana, and Nijagara). The experiment was conducted under semi-controlled conditions in a completely randomized block design. The number of nodules, mycorrhizal colonization, dry matter yield of shoots and roots, protein yield, and phosphorus content were assessed. Acidic soil (pHKCl 4.55) was used for sowing, no lime (L0), alongside treatments on soils limed with 1 t ha-1 (L1) and 2.5 t ha-1 (L2) of Ca(OH)₂. The results indicated that rhizobia application increased the dry matter yield of shoots and roots. Protein yield at the L1 liming level ranged from 13.1 g/kg in the control treatment to 16.9 g/kg in the treatment with rhizobia, while at the L2 liming level, it ranged from 17.6 g/kg in the control treatment to 25.1 g/kg in the treatment with co-inoculation. Pre-sowing inoculation with mycorrhizal fungi and co-inoculation increased mycorrhizal colonization and phosphorus content. The results indicate the positive effects of both single and co-inoculation on alfalfa productivity. The impact of inoculation with the selected rhizobia strain was more pronounced in acidic soils than in limed soils and was cultivar-dependent. Therefore, the key to increasing alfalfa output in acidic soils is matching the strain with the cultivar.