RESUMO
Chickpea is a crucial leguminous crop and India is the leading producer, with an average yield of 1.18 tons/ha. It is renowned for its specific nodulation with rhizobia. Despite its significance, studies on chickpea-nodulating rhizobia often focused on small-scale investigations within restricted geographical areas. This study delves into the population, genetic diversity, and symbiotic efficiency of chickpea-nodulating rhizobia in the Indo-Gangetic Plains (IGP) of India. The study revealed a low population of chickpea rhizobia (ranging from 11 to 565 cells/g dry soil) across the examined area. Only three samples exhibited a population exceeding 300 cells/g, emphasizing the potential need for inoculation of rhizobia with efficient and competitive strains. Correlation analysis highlighted a significant positive correlation between rhizobial population and organic carbon content, among various soil parameters like pH, electrical conductivity, available nitrogen (N), phosphorus (P), potassium (K), and organic carbon content. Among the 79 presumptive rhizobia isolated from 24 IGP locations, 61 successfully nodulated chickpea cultivar Pusa 362. 16S rRNA gene sequencing categorized 54 isolates as Mesorhizobium, four as Rhizobium, and three as Ensifer. Genetic diversity assessed by BOX-PCR revealed sixteen distinct banding patterns, underscoring substantial variability among the strains. The strains exhibited plant growth-promoting activities, salt tolerance up to 3% NaCl, and pH tolerance between 4 and 10. Six symbiotically efficient strains were identified based on their positive impact on nodulation and dry biomass. This study provides crucial insights into the diversity, genetic makeup, and symbiotic efficiency of chickpea rhizobia in the IGP, supporting the potential use of indigenous rhizobia for sustainable chickpea productivity in the region.
RESUMO
In the present study, we studied the distribution of silicate mineral weathering bacteria (SWB) in stressed environments that release potassium from insoluble source of mineral. Out of 972 isolates, 340 isolates were positive and mineral weathering potential ranged from 5.55 to 180.05%. Maximum abundance of SWB occurred 44.71% in saline environment followed by 23.53% in low temperature and 12.35% each in high temperature and moisture deficit. Among isolates, silicate mineral weathering efficiency ranged from 1.9 to 72.8 µg mL-1 available K in liquid medium. The phylogenetic tree of SWB discriminated in three clusters viz. Firmicutes, Proteobacteria and Actinobacteria. This is the first report on SWB in stressed environments and identified 27 genera and 67 species which is not reported earlier. Among them Bacillus was the predominant genera (58.60%) distantly followed by Pseudomonas (6.37%), Staphylococcus (5.10%) and Paenibacillus (4.46%). These bacterial strains could be developed as inoculants for biological replenishment of K in stressed soils. Graphical abstract.