Novel Strains of Pseudomonas fluorescens and Bacillus cereus and their Integrated use with Inorganic Fertilizers Enhancing P Availability, Crop Growth Parameters, and Sugarcane Yield in Subtropical India

Sugarcane is a commercial and bio-energy crop and being cultivated in more than 120 countries. Indiscriminate application of chemically synthesized fertilizers caused negative and unpredictable effects on soil, environment and human health. The applied fertilizers have poor nutrient use efficiency (30–40%), and almost 60–70% of fertilizers go waste, ultimately causing hazards in the ecosystem. Extensive research is needed to improve fertilizer use efficiency and sustain sugarcane yield at a higher level. Keeping the significant role of PGPRs in sugarcane crops, we isolated P solubilizing bacterial strains and characterized them under in-vitro conditions. Further, we rigorously validated them in field conditions with different P fertilizer levels. The field experiment was conducted during 2018–19 and 2019–2020 at low-level P content in soil (11 kg ha −1 ) by cultivating high yielding high sugar content variety—Co 0238 of the sub-tropical India. The inoculated P solubilizers improved soil enzyme activities, increased microbial population (2.3 × 10 7 cfu g −1 of soil), phosphorus (P 2 O 5 ) availability (50.02 kg ha −1 ), P uptake (53.80 kg ha −1 ), increased dry matter accumulation (44.20 tonnes ha −1 ), and photosynthetic rate (24.69 µmol m −2 s −1 ) over the recommended P fertilizers application. The inoculated plots with Pseudomonas fluorescens (PSB28) along with 45 kg P 2 O 5 ha −1 (75% of the recommended dose) improved sugarcane yield by 23.20% (98.09 tonnes ha −1 ) compared to 60 kg P 2 O 5 ha −1 (75.33 tonnes ha −1 ). The increased number of millable canes (99,930 ha −1 ) and single cane weight (986.3 g) were also recorded in inoculated plots with the PSB strain. The findings support the use of efficient PGPRs strains in sugarcane crops could result in increased P availability, enhanced crop production with the reduced application of P fertilizer, and improved nutrient use efficiency in sugarcane crop under sub-tropical conditions in India.