**3.2 Assessment of plant growth promoting determinants**

Three plant growth promoting determinants viz. siderophore and IAA production as well as phosphate solubilization capability were assessed. The results revealed that the development of yellow-orange halo zone around the bacterial growth on chrome azurol S agar plates was considered as positive (+) for siderophore production, formation of pink color by the culture supernatant of the bacterial isolates in presence of Salkowski's reagent confirmed IAA production which was indicated by '+" sign and observation of clear halo zone in National Botanical Research Institute's phosphate (NBRIP) agar plates indicated the bacterial *Potential Role of Rice Plant Growth Promoting Phylloplane and Rhizospheric Bacteria… DOI: http://dx.doi.org/10.5772/intechopen.99854*

#### **Figure 3.**

*PCR confirmation of the antagonistic bacterial isolates by amplification of 16S rDNA using primers 27F and 1518R obtained from plant samples collected in irrigated and rainfed seasons. These PCR products were then used for sequencing. Bacterial isolates obtained from (A) irrigated: BDISOB04P, BDISOB05P, BDISOB16P, BDISOB98P, BDISOB241P, BDISOB242P, BDISOB219R, BDISOB220R, BDISOB221R, BDISOB222R, BDISOB258R, BDISOB272R, BDISOB275R, BDISOB186R, BDISOB283R, BDISOB306R, BDISOB53R and BDISOB61R. (B) Rainfed: BDISO04P, BDISO45P, BDISO53P, BDISO356P, BDISO198P, BDISO135P, BDISO148P, BDISO92P, BDISO237P, BDISO12P, BDISO196P, BDISO145P, BDISO09P, BDISO21R, BDISO154P, BDISO147P, BDISO158R, BDISO0R, (C) irrigated: BDISOB37R, BDISOB16R, BDISOB91R, BDISOB17R, BDISOB15R, BDISOB86R, BDISOB30R, BDISOB92R, BDISOB178R, BDISOB11R, BDISOB21R, BDISOB24R, BDISOB23R and BDISOB14R: a rhizosphere isolate, Cumilla and (D) rainfed: BDISOB70R, BDISOB54R, BDISOB08R, BDISOB31R*, *BDISOB06R, BDISOB171R, BDISOB46R, BDISOB09R, BDISOB33R, BDISOB11R, BDISOB36R, BDISOB07R, BDISOB172R and BDISOB12R.*

isolates are capable of phosphate solubilization which was denoted by "+" sign (**Figure 3**). Out of these bacterial species, Out of these bacterial species, 48 bacterial species were found as positive for IAA production, all 63 bacterial species were found positive for siderophore production and 48 were found capable to solubilize insoluble phosphate. In case of Indole Acetic Acid (IAA), BDISOB92FarR (*Pseudomonas fluorescens),* BDISOB172ThaR (*B. aerophilus*), BDISOB45PanP (*Bacillus paramycoides),* BDISOB01MymR (*Bacillus amyloliquefacience)* showed highest IAA production. Whereas, BDISOB186KusR (*Bacillus paramycoides)* showed lowest IAA production. BDISOB54KhuR (*B. gladioli) and* BDISOB21ChaR (*S. maltophilia)* indicataed moderate IAA production. BDISOB198HabP (*Seratiaplymuthica),* BDISOB148JoyP (*Seratia marcescens),* BDISOB145JoyP (*Seratia marcescens),* BDISOB07FarR (*Seratianematodiphilia),* BDISOB12FarR (*Seratia marcescens),* BDISOB31MagR (*Seratia marcescens),* BDISOB46GopR (*Seratia marcescens)* and BDISOB70KusR (*Seratia marcescens)* were statistically similar. The bacterial isolatesBDISOB222GaiR (*P. plecoglossicida),* BDISOB45PanP (*Bacillus paramycoides)* BDISOB01MymR (*B. amyloliquefaciens)* BDISOB04KhaP (*P. putida),* BDISOB05MymP (*P. putida*), BDISOB221GaiR (*Pseudomonas sp.)* showed highest siderophore production. Whereas, BDISOB135SerP (*Bacillus sp.),* BDISOB145JoyP (*Seratia marcescens) and* BDISOB21ChaR (*Stenotrophomonas maltophilia)* showed


#### **Table 2.**

*List of antagonistic bacterial isolates identified by homology search ofsequences of 16SrDNA by BLAST program obtained from plant samples collected in aman season 2018.*

lowest siderophore production. The Sierophore production found in BDISOB219GaiR (*P. taiwanensis)*, BDISOB186KusR (*Pseudomonas sp.),* BDISOB283KisR (*Pseudomonas fluorescens),* BDISOB198HabP (*Seratiaplymuthic),* BDISOB54KhuR (*B. gladioli)* and BDISOB21ChaR (*S. maltophilia)* BDISOB198HabP (*Seratia plymuthica),* BDISOB148JoyP (*Seratia marcescens),* BDISOB158ChaR (*Seratia marcescens)* BDISOB148JoyP (*Seratia marcescens),* BDISOB145JoyP (*Seratia marcescens),* BDISOB07FarR (*Seratia nematodiphilia),* BDISOB12FarR (*Seratia marcescens),* BDISOB31MagR (*Seratia marcescens),* BDISOB46GopR (*Seratia marcescens)* and BDISOB70KusR (*Seratia marcescens)* were statistically similar. The bacterial isolates BDISOB05MymP (*P. putida*), BDISOB45PanP (*Bacillus paramycoides)* and BDISOB01MymR (*B. amyloliquefaciens)* showed highest siderophore production. Whereas, BDISOB186KusR (*Pseudomonas sp.),* BDISOB258GaiR (*P. putida) and* BDISOB70KusR (*Seratia marcescens)* showed lowest phosphate solubilization activity. The others bacteria in case of phosphate solubilization were statistically similar.
