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Livestock production in Afghanistan highly relies on grazing and clover feed, which is a key component of pastures and forage crops. This study elucidated the genetic diversity of clover-nodulating rhizobia in different ecological regions and their effects on clover growth. A total of 57 rhizobia were isolated and their genetic diversities were studied through 16S rRNA and nifD genes. The isolates were inoculated to clover (Afghan local variety), to investigate the potential of nitrogen fixation and influences of clover growth. The 16S rRNA gene analysis showed two distinct groups of Rhizobium (94.7%) and Ensifer (5.3%) species. The nifD phylogenetic relationship revealed a high similarity to Rhizobium and a novel lineage group close to Rhizobium leguminosarum species. In the plant test, different genotypes significantly (p < 0.01) exhibited an increase in plant biomass production, compared to the un-inoculated plants. Among genotypes, the highest plant biomass was recorded in PC8 (1769.0 mg/plant) and PC9 (1409.2 mg/plant) isolates as compared to un-inoculated plants (144.0 mg/plant). Moreover, these isolates showed maximum nitrogen fixation rates of 8.2 and 6.5 µM/plant, respectively. These isolates were identified as the most promising rhizobial strains for developing biofertilizers in the context of Afghanistan. [ABSTRACT FROM AUTHOR]

Developing multi-functional, environmentally friendly biofertilizers can help reduce chemical fertilizer usage. This study examined single and combined application effects of four plant growth-promoting rhizobacteria (PGPR) strains: AF124 (Rhizobium daejeonense), AF74 (Enterobacter cloacae), AF96 (Pseudomonas putida), and AF42 (Enterobacter cloacae), isolated from alkaline salt-stressed soils from Afghanistan. Physiological features such as nitrogen (N2) fixation, indole-3-acetic acid (IAA), organic acid production, and P and K solubilization of bacteria in single or combined cultures in vitro were examined. A single application of AF124 and AF74 showed significantly higher IAA production than the combined application of dual, triple, and quadruple PGPR treatments. Regarding acetylene reduction activity, an N2-fixation activity indicator, a single application of AF124 showed the highest value, followed by a triple application of AF124 + AF96 + AF42. The P-solubilization activity and organic acid production were lower in the single application of AF124 but higher with other strains in the combined applications, which resulted in the secretion of multiple organic acids into the medium. The highest solubilized K value was obtained from the quadruple application compared to other treatments. In the rice inoculation test, all single and combined PGPR treatments increased its growth parameters, such as root length and root and shoot dry biomass. The present results indicate that these four PGPR strains can potentially contribute to developing multi-functional bio-fertilizer formulations. [ABSTRACT FROM AUTHOR]