Acetylene reductase activity and molecular characterization of plant growth promoting rhizobacteria to know efficacy in integrated nutrient management system

Abstract

<span style="font-size:11.0pt;font-family:" times="" new="" roman","serif";="" mso-fareast-font-family:"times="" roman";mso-bidi-font-family:mangal;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:hi"="">Isolates from rhizosphere were screened and characterized for their plant growth promotion and biocontrol properties as per standard methods. Five isolates (MK₂, MK₄, MK₅, MK₇ & MK₉) showed the maximum plant growth promoting attributes like P-solubilization, N-fixation etc. Acetylene reduction assay (ARA) method was used to study N₂ fixing ability. The bacterial isolate MK₅ fixed the maximum nitrogen, <i>i.e.</i>, 437.26 ηmole C₂H₄ h^-1 mg^-1protein (109 mg of N₂ fixed/ha/d).<span style="mso-bidi-font-weight:bold"> The isolates MK₅ and MK₇ showed the maximum homology with <i style="mso-bidi-font-style:normal">Bacillus pumilus </i>and <i style="mso-bidi-font-style:normal">B. subtilis</i><span style="mso-bidi-font-style:italic">,<i style="mso-bidi-font-style:normal"> </i>respectively by 16S rRNA analysis. The bacterial isolate MK₅ in conjunction with 75% level of recommended dose of N and P fertilizers gave increase yield of cauliflower crop by 27.29% over recommended doses of NPK with a saving of 25% N and 25% P fertilizers.</span></span></span>