Plant-Growth-Promoting Rhizobacteria Consortia for Growth and Yield Improvement in Rice

High-yielding rice varieties are highly fertilizer responsive for high productivity. Plantgrowth- promoting rhizobacteria (PGPR) offers a valuable alternative to reducing the usage of chemical fertilizers. Field evaluation was carried out to evaluate the efficiency of three novel consortia of PGPR-on rice growth and yield in the Wayanad District of Kerala, India. These three consortia were produced using native PGPRs from the rice soil of Wayanad District, India, and each consortium consisted of two nitrogen fixers, one phosphate solubilizer, one potassium solubilizer, and one zinc solubilizer. Two novel PGPR-based consortia were selected from pot culture evaluation of rice growth and yield. These selected consortia were further evaluated with a commercially available PGPR-based consortium namely PGPR mix-1 under field conditions. Five treatments viz, T₁ : consortium 2 + 75 % recommended dosage of fertilizer (RDF), T₂ : consortium 3 + 75% RDF, T3 : PGPR mix^-1 (KAU consortium) + 75 % RDF, T₄: 100% RDF and T₅ : farmer’s practice (farm yard manure 5 t ha-1) were used. The results indicated that root colonization of total bacteria, N fixers, phosphate, K, and Zn solubilizers was higher in plants treated with PGPR consortia with 75 % inorganic fertilizer than 100 % RDF and farmer’s practice. Rice growth and yield parameters showed that new PGPR consortia 2 with 75% inorganic fertilizer was statistically on par with 100% RDF. Among the tested PGPR consortia, consortium 2 was able to colonize the rice rhizosphere successfully and, significantly increased nutrient availability in soil, nutrient content in plant tissues while producing a significantly higher yield that could reduce 25% of inorganic nitrogen, phosphorus, and potassium fertilizer.