ABSTRACT
Adaptive potential of legume-rhizobia symbiosis under saline soil conditions: Comparative evaluation of native salt-tolerant rhizobial inoculants

Seda Harutyunyan1, Tamara Stepanyan1, Gayane Khachatryan1, Ruzanna Hovhannisyan1, Anna Zakoyan1, Vahagn Hakobyan1, and Vigen Goginyan1*
 
Soil salinization is a major global constraint to sustainable agriculture because it severely limits legume productivity by disrupting both plant growth and biological N fixation. This study aimed to evaluate the symbiotic efficiency and agronomic potential of native salt-tolerant rhizobial strains isolated from naturally saline soils of the Ararat Valley, Armenia, for improving legume performance under saline conditions. A two-layer soil-sand system was developed to simulate progressive root-zone salinity under field-relevant conditions, using a non-saline upper layer for seed establishment and a saline lower horizon (electrical conductivity 4.0-6.2 dS m¹) for stress exposure. Selected strains were tested on soybean (Glycine max (L.) Merr.), peanut (Arachis hypogaea L.), chickpea (Cicer arietinum L.), pea (Pisum sativum L.), lentil (Lens culinaris Medik.), fenugreek (Trigonella foenum-graecum L.), and common bean (Phaseolus vulgaris L.) by assessing nodulation, plant growth, biomass accumulation, seed productivity, and seed protein content. In soybean, inoculation with selected Bradyrhizobium japonicum strains increased yield by 37%-45% relative to the non-inoculated control (P < 0.05), with strain MDC 5789 showing the highest symbiotic efficiency. In peanut, strain MDC 5812 increased productivity by 125% (P < 0.05). Across all tested legumes, inoculation significantly improved nodulation and plant growth under salinity, although the magnitude of response was strongly host dependent. In common bean, strain MDC 5700 maintained effective nodulation under 6.2 dS m¹ and increased shoot biomass and seed protein content by 11.1% (P < 0.05). These results demonstrate that indigenous salt-tolerant rhizobia are promising candidates for development of region-specific biofertilizers and represent an effective biological strategy for improving legume productivity and sustainability in salt-affected agroecosystems.
Key words: Common bean, chickpea, fenugreek, legume-rhizobium symbiosis, lentil, microbial inoculants, pea, peanut, salt-tolerant rhizobia, soil salinity, soybean.
1Scientific and Production Center “Armbiotechnology” of the National Academy of Sciences, Yerevan, Armenia.
*Corresponding author (goginyan@gmail.com).
Received: 25 May 2026; Accepted: 7 September 2026, Available online: 29 October 2026.