Plant growth-promoting traits of biocontrol potential bacteria isolated from rice rhizosphere

PGP and biocontrol traits bacteria download paper

Subramaniam Gopalakrishnan, H D Upadhyaya, Srinivas Vadlamudi, Pagidi Humayun, Meesala Sree Vidya, Gottumukkala Alekhya, Amit Singh, Rajendran Vijayabharathi, Ratna Kumari Bhimineni, Murali Seema, Abhishek Rathore, and Om Rupela

Abstract

Seven isolates of bacter ia (SR I-156, SRI-158, SRI-178, SRI-211 , SRI-229, SRI-305 and SRI-360) were earlier reported by us as having poten tial for biocontrol of charcoal rot of sorghum and plant growth promotion (PGP) of the plant. In the present study, the seven isolates were ch aracterized for their physiological traits (tolerance to salinity , pH, temperature and resistance to antibioti cs and fungi cides) and further evaluate d i n the field for their PGP of rice. All the seven isolates were able to grow at pH values between 5 and 13, in NaCl concentrations of up to 8% (exc ept SRI-156 and SRI-360 ), temperatures between 20 and 40°C and were resistant to ampicillin (>100 ppm; except SRI-158 and SRI-178 ) but sensit ive (<10 ppm) to ch loramphenicol, kanamycin, nalidix ic aci d, streptomycin (except SRI-156 and SRI-211 ) and tetracycline. They were tolerant to fungicides benlate and captan, except SRI-158 and SRI-178, bavist in and sens itive to thiram (except SRI-156 and SRI-211 ) a t field application level. In the field, four of the seven isolates (SRI-158, SRI-211 , SRI-229 and SRI-360) significantly enhanc ed the tiller numbers, stover and grain yields, to tal dry matter, root length, volume and dry weight over the un-inocul ated control. In the rhizosphere soil at harvest, all the isolates signif icantly enhanced microb ial biomass carbon (except SRI-156 ), microbial biomass nitrogen and dehy drogenase activi ty (up to 33%, 36% and 39%, respectively) and total N, availabl e P and% organic carbon (up to 10%, 38% and 10%, respectivel y) compared to the control. This investigation further confirms that th e SRI isolates have PGP properties.