Isolation and Characterization of Plant Growth Promoting Rhizobacteria for Growth Promotion of Rice (Oryza sativa L.) and Wheat (Triticum aestivum)

Abstract

The use of rhizobacteria for plant growth enhancement is decades old. Still, in this era of the 21st century, biofertilizers have become the need of the day due to the health and environmental concerns associated with chemical fertilizers and pesticides. Rhizobacteria strains were isolated from the rhizosphere of rice and wheat. The selected bacterial strains' nitrogen fixation, indole acetic acid (IAA) production, phosphorus solubilization, and antifungal activity were determined on morphological, biochemical, and molecular levels. Production of IAA ranged from 6 µg/ml to 29.33 µg/ml. Ethylene production (C₂H₄/hr) varied from 2 µmoles to 9.8 µmoles. Maximum Phosphorus Solubilization index (7), decrease in pH (4) and Solubilization % age (0.49) was observed in WM-2 (wheat microbe). Promising results were obtained concerning antifungal activity against Rhizoctonia solani and Fusarium sp. The effect of the potential PGPR strains on the germination of rice and wheat was significantly positive in Petri plates. In the case of rice, the highest shoot length (29.27 cm) was observed by inoculation with RPR-33 (Rice isolate), and the most increased root length (9.33 cm) was observed in the treatment inoculated with RPR-42. The highest shoot fresh weight (476.67 mg/plant) was recorded in the treatment inoculated with RPR-42. The maximum root weight was 170 mg/plant in the same treatment. For wheat, all recorded growth parameters were improved significantly by wheat microbe WM-5. All the PGPR isolates showed positive results for growth parameters of wheat and rice on inoculation. So, it is suggested that these PGPR isolates may be used in potential biofertilizers.