Legume Research - An International Journal

The influence of rhizospheric properties on nodulation status and resident rhizobial population of pea and lentil grown at twenty three sites of Assam were assessed. Besides the plant infectivity of rhizobia isolated from pea and lentil nodules were tested for symbiotic effectiveness. The survey established significant variation of nodule number ((35.0–223.8/plant)), nodule dry weight (69.6 to 271.8 mg/plant) and most probable number count (9 to 14700/g soil) across the twenty three diverse sites. Rhizospheric properties viz pH, organic carbon, available P₂O₅ and K₂O could establish significant correlation with nodule number (r=0.892*, 0.771*, 0.753* and 0.669*) and most probable number(r=0.784*, 0.580*, 0.615* and 0.649*) counts, correspondingly. Microbial biomass carbon showed significant correlation with nodule number(r=0.672*). Dehydrogenase and phosphomonoesterase activities too showed significant correlation with nodule number(r=0.695* and 0.634*) and most probable number (r=0.575* and 0.534*) count, respectively. The symbiotic effectiveness of isolated rhizobia demonstrated significant variation of nodule score (1.33–3.67). Only 6 isolates could attain nodule score of ≥3.0, irrespective of resident rhizobial population.