ORIGINAL PAPER

Rhizosphere competent Pantoea agglomerans enhancesmaize (Zea mays) and chickpea (Cicer arietinum L.) growth,without altering the rhizosphere functional diversity

Aradhana Mishra • Puneet Singh Chauhan •

Vasvi Chaudhry • Manisha Tripathi •

Chandra Shekhar Nautiyal

Received: 6 May 2011 / Accepted: 24 May 2011 / Published online: 3 June 2011

� Springer Science+Business Media B.V. 2011

Abstract Plant growth promoting Pantoea agglom-

erans NBRISRM (NBRISRM) was able to produce

60.4 lg/ml indole acetic acid and solubilize 77.5 lg/

ml tri-calcium phosphate under in vitro conditions.

Addition of 2% NaCl (w/v) in the media induced the

IAA production and phosphate solubilization by 11%

and 7%, respectively. For evaluating the plant growth

promotory effect of NBRISRM inoculation a micro

plot trial was conducted using maize and chickpea as

host plants. The results revealed significant increase

in all growth parameters tested in NBRISRM inoc-

ulated maize and chickpea plants, which were further

confirmed by higher macronutrients (N, P and K)

accumulation as compared to un-inoculated controls.

Throughout the growing season of maize and chick-

pea, rhizosphere population of NBRISRM were in the

range 107–108 CFU/g soil and competing with 107–

109 CFU/g soil with heterogeneous bacterial popula-

tion. Functional richness, diversity, and evenness

were found significantly higher in maize rhizosphere

as compared to chickpea, whereas NBRISRM inoc-

ulation were not able to change it, in both crops as

compared to their un-inoculated control. To the best

of our knowledge this is first report where we

demonstrated the effect of P. agglomerans strain for

improving maize and chickpea growth without alter-

ing the functional diversity.

Keywords Chickpea (Cicer arietinum L.) � Maize

(Zea mays) � Pantoea agglomerans � Functional

diversity � Nutrient uptake

Introduction

The use of beneficial soil plant growth promoting

rhizobacteria (PGPR) for improving crop production

requires the selection of rhizosphere-competent bac-

terial strains with multiple plant growth promoting

attributes (Nautiyal et al. 2008; Hynes et al. 2008).

The group of these beneficial PGPR belongs to

various genera e.g. Acetobacter, Acinetobacter, Alca-

ligenes, Arthrobacter, Azospirillum, Azotobacter,

Bacillus, Burkholderia, Enterobacter, Gluconacetob-

acter, Herbaspirillum, Klebsiella, Methylobacterium,

Ochrobactrum, Pantoea, Pseudomonas, Rhodococ-

cus, Serratia, and Stenotrophomonas (Babalola

2010). Among the above mentioned beneficial PGPR,

Pantoea agglomerans is a member of Enterobacteri-

aceae found everywhere in nature and inhabiting

plants, soil, water, animals and humans (Wright et al.

2001; Chauhan and Nautiyal 2010). Several isolates

of P. agglomerans are known to improve the plant

growth promotion by various mechanisms which

A. Mishra � P. S. Chauhan � V. Chaudhry �M. Tripathi � C. S. Nautiyal (&)

Division of Plant Microbe Interactions, National

Botanical Research Institute, Rana Pratap Marg,

Lucknow 226001, India

e-mail: nautiyalnbri@lycos.com

123

Antonie van Leeuwenhoek (2011) 100:405–413

DOI 10.1007/s10482-011-9596-8

mainly includes solubilization of inorganic phosphate

(Son et al. 2006), phytohormone production (Dastag-

er et al. 2009), nitrogen fixation (Loiret et al. 2004),

reduction of ethylene level by the enzyme 1-amino-

cyclopropane-1-carboxylate (ACC) deaminase (Long

et al. 2008) and biological control activity (Braun-

Kiewnick et al. 2000; Canamas et al. 2009) etc.

In many cases PGPR fail to induce the desired

effects when inoculated under the field conditions

because of poor colonization of the rhizosphere of

host plants, which is the most important requirement

for any PGPR for exhibiting all beneficial effects for

crop production (Lugtenberg et al. 2001; Nautiyal

et al. 2008). In fact, any exogenous strain has to

compete with a well-established rhizosphere micro-

flora in order to colonize in the rhizosphere of host

plant effectively. Different biotic and abiotic factors

influence plant development and bacterial diversity

associated with them (Andreote et al. 2010).

The bacterial diversity associated with different

plants in the same soil differ (Salles et al. 2004) and

inoculated efficient PGPR may survive, proliferate

and sometimes even alter the microbial diversity of

the host’s rhizosphere depending on their interactions

with the indigenous rhizosphere microflora (Andreote

et al. 2010; Nautiyal et al. 2010a). However, the

effects of bacterial inoculation on bacterial commu-

nity composition in different host plants are rarely

studied. Functional diversity based on sole carbon

source utilization pattern is a rapid, community level

approach for assessing the changes in the patterns of

host plant rhizosphere microbial diversity due to

inoculation of plant growth promoting microbes

(Nautiyal et al. 2010a, b, c).

In the present study, we aimed to evaluate the

effect of P. agglomerans NBRISRM inoculation in

promoting the chickpea (Cicer arietinum L.) and

maize (Zea mays) plant growth, macronutrient uptake

and followed by evaluating the changes in the

rhizosphere functional diversity of the two crops.

Materials and methods

Bacterial strain and growth conditions

Chickpea rhizosphere-competent Pantoea agglomer-

ans NBRISRM (NBRISRM) was isolated from the

roots of field-grown chickpea (C. arietinum L.) as

described earlier by Nautiyal (1997). Pure culture of

NBRISRM was grown and maintained on nutrient

broth (NB) or nutrient agar (NA) (HI-MEDIA Labo-

ratories, Bombay, India) and in 30% glycerol stocks

stored at -80�C. Identification of P. agglomerans

SRM was based on 95 carbon source utilization

pattern, using Biolog GN2 microtitre panels by fully

automated Biolog Bacteria Identification system (Bio-

log Inc., Hayward, CA, USA) as described earlier by

Nautiyal et al. (2007). Biolog microlog GN release

6.01 Database used for identification of the P. agglom-

erans SRM showed closest homology with P. agglom-

erans with 99% probability. Further identification of

SRM was based on 16S rDNA sequence analysis.

A PCR product of 1465 base pairs 16S rDNA was

sequenced, and data were analysed as described earlier

(Dastager et al. 2009). Sequence data of SRM have

been deposited in the GenBank, nucleotide sequence

database under the accession number GQ225111.

Sequence analysis of the isolate was compared with

16S rRNA sequences using BLAST search in the

NCBI, GenBank database (http://www.ncbi.nlm.

nih.gov). Multiple sequence alignments were per-

formed using CLUSTAL-X (Thompson et al. 1997).

The method of Jukes and Cantor (1969) was used to

calculate evolutionary distances. Phylogenetic den-

drogram was constructed by the neighbour-joining

method (Felsenstein 1985) and tree topologies were

evaluated by performing bootstrap analysis of 1,000

datasets using MEGA 4 (Molecular Evolutionary

Genetic Analysis).

IAA production and phosphate solubilization

by P. agglomerans NBRISRM

IAA production was detected by the modified method

as described by Brick et al. (1991). Bacterial cultures

were grown for 72 h in NB media containing trypto-

phan (100 lg/ml) at 30 ± 2�C. Fully grown cultures

were centrifuged at 3,000 rpm for 30 min. The super-

natant (1 ml) was mixed with 100 ll of orthophos-

phoric acid and 4 ml of the Salkowski reagent (50 ml,

35% of perchloric acid, 1 ml 0.5 M FeCl3 solution).

Development of pink color indicated IAA production.

Optical density was taken at 530 nm using Spectronic

20 D? spectrophotometer (Milton Roy Company,

USA). The concentration of IAA produced by cultures

was compared to standard curves of known IAA

(Hi-media) concentrations from the range of 10–100 lg/

406 Antonie van Leeuwenhoek (2011) 100:405–413

123

ml. National Botanical Research Institute’s phosphate

growth medium (NBRIP) which contained (l-1): glu-

cose, 10 g; Ca3(PO4)2, 5 g; MgCl2�6H2O, 5 g;

MgSO4�7H2O, 0.25 g; KCl, 0.2 g, and (NH4)2SO4,

0.1 g, was used to check the phosphate solubilization

by NBRISRM (Nautiyal 1999). The amount of soluble

phosphate was determined using the Fiske and Subbarow

method (Fiske and Subbarow 1925). Blank samples were

prepared by omitting 1-amino-2-naphthol-4-sulfonic

acid from the assay system as described earlier (Mehta

and Nautiyal 2001). The effects of temperature, salt and

pH were evaluated on the IAA production and phosphate

solubilization ability of NBRISRM in 150 ml Erlen-

meyer flasks containing 50 ml NB with tryptophan

(100 lg/ml) and NBRIP, respectively. The following

conditions were tested: for salt tolerance experiments 2

and 4, % NaCl (w/v), for temperature tolerance flasks

were incubated at 30 and 37�C and for pH tolerance

experiments, pH 9 of medium maintained by adding

NaOH in the media.

Plant growth promotion assay

Micro plot trial was carried out in the field of the

National Botanical Research Institute, Lucknow in a

randomized block design with four replicates using

host plant maize (Zea mays cv. Arkil) and chickpea

(Cicer arietinum cv. Radhey) as described earlier

(Nautiyal et al. 2010a, b). Bacterial inoculum of SRM

for maize and chickpea seeds was prepared by

suspending a 48 h grown culture from NA plates at

28�C in 10 ml of 0.85% saline Milli-Q water (MQW),

containing about 8 log10 CFU/ml. Surface-sterilized

maize and chickpea seeds were soaked in the bacterial

suspension for 4 h at 28�C on a reciprocal shaker at

100 rpm. Control seeds (non-bacterized) were soaked

in 0.85% saline MQW washed from uninoculated NA

plates (Nautiyal et al. 2010a). Each treatment was

raised in eight rows, each of 8 m length 6 m width,

with an intra- and inter-row spacing 10 and 60 cm,

respectively. Harvesting of maize and chickpea was

done at 90 and 105 days after sowing (DAS), respec-

tively and data was recorded as described earlier

(Nautiyal et al. 2010a, b).

Nutrient uptake

Twelve plants chosen at random harvest were rinsed

with Milli-Q water and oven-dried at 75�C for 72 h.

The dried shoot tissues were ground and then

digested using concentrated HNO3 (Page et al.

1982) for the determination of K using an atomic

absorption spectrometer. Total N and P were

extracted by digesting shoot tissue with 3 ml con-

centrated H2SO4 and 1 ml H2O2, respectively, at

360�C, and determined by the Berthelot reaction and

molybdenum blue method, respectively (Page et al.

1982). The amount of NaHCO3-extractable P (avail-

able inorganic P) from the dried shoot tissues was

determined by extracting samples with 0.5 M

NaHCO3 (pH 8.5) at a solution/solid ratio of 20:1

for 30 min (Olsen and Sommers 1982).

Tracking of P. agglomerans NBRISRM

in the rhizosphere of maize and chickpea

In order to monitor the presence of NBRISRM on

plant roots grown in non-sterilized soils, a spontane-

ous rifampicin-resistant (Rifr) strain of NBRISRM

was isolated on NA plates, containing 250 lg rifam-

picin (from Sigma Chemical Co., St. Louis, MO,

USA) as described earlier (Nautiyal 1997). Hetero-

geneous rhizosphere bacterial population was recov-

ered by serial dilution plating of the homogenate on

NA plates and NA plates amended with 50 lg

rifampicin/ml for NBRISRM. Average rhizosphere

colonization of NBRISRM (log10 CFU/g root dry

weight) was determined from four plants at the time

of harvesting each at different time interval as

indicated.

Effect of P. agglomerans NBRISRM inoculation

on functional diversity of maize and chickpea

rhizosphere based on carbon source utilization

pattern

Biolog Eco plates (Biolog, Inc., Hayward, CA, USA)

were used to determine the carbon source utilization

pattern as described earlier Nautiyal et al. (2010a, b).

Four rhizosphere soil samples were collected from

maize and chickpea plants with and without

NBRISRM inoculation. For each soil samples 12

samples were collected and three composite samples

were made by mixing four samples together. Indi-

vidual rhizosphere soil samples (1.0 g) were shaken

in 9.0 ml of sterile saline (0.85% NaCl w/v in Milli-Q

Water) for 60 min and then make up to a final

dilution of 10-3. After incubation, 150 ll of sample

Antonie van Leeuwenhoek (2011) 100:405–413 407

123

was inoculated in each well of Biolog Eco plates and

incubated at 30�C. The rate of utilization is indicated

by the reduction of tetrazolium, a redox indicator dye,

which changes from colorless to purple. Data were

recorded for 7 days at 590 nm and the results

obtained at fourth day were used for statistical

analysis. Microbial activity in each microplate,

expressed as average well color development

(AWCD) was determined as described by Garland

(1996). Diversity, richness and evenness indices were

calculated as described by Nautiyal et al. (2010a, b).

Statistical analyses were performed using SPSS 16.0

and Statistica 7.0.

Results

Isolation and identification of P. agglomerans

NBRISRM

A potential bacterial strain showing IAA production

and phosphate solubilization under in vitro conditions

was isolated from chickpea rhizosphere soil. Identi-

fication of SRM was based on 95 carbon source

utilization pattern using Biolog GN2 microtitre

panels by fully automated Biolog bacteria identifica-

tion system (Biolog Inc., Hayward, CA, USA) as

described earlier by Nautiyal et al. (2007). Further

identification of SRM was based on 16S rRNA gene

sequence analysis. A PCR product of 1,465 base pairs

16S rRNA gene was sequenced, and data were

analyzed as described earlier (Dastager et al. 2009).

The phylogenetic tree was constructed using 16s

rRNA gene sequence showing closest phylogenetic

relationship with P. agglomerans DSM3493T with

99% homology. Sequence data of SRM have been

deposited in the GenBank, nucleotide sequence

database was under the accession number

GQ225111 (Fig. 1).

IAA production and phosphate solubilization

by P. agglomerans NBRISRM

IAA production and phosphate solubilization of

NBRISRM was evaluated under in vitro conditions.

Figure 2 shows that NBRISRM produced 60.4 lg/ml

IAA and solubilized 77.5 lg/ml tri-calcium phosphate

after 72 h incubation under optimum conditions (0%

NaCl, pH-7 and 30�C) in their respective medium. IAA

production and phosphate solubilization of the

Pantoea agglomerans NBRISRM (GQ225111)

Pantoea agglomerans DSM 3493T(AJ233423)

Pantoea conspicua LMG 24534T(EU216737)

Pantoea brenneri LMG 5343T(EU216735)

Pantoea eucalypti LMG 24198T(EF688009)

Pantoea ananatis ATCC 19321T(U80209)

Pantoea vagans LMG 24199T(EF688012)

Pantoea anthophila LMG 2558T(EF688010)

Pantoea deleyi LMG 24200T(EF688011)

Pantoea stewartii LMG 2715T(Z96080)

Pantoea gaviniae A18/07T(GQ367483)

Pantoea calida1400/07T(GQ367478)

Erwinia toletana A64(AF130963)

Erwinia amylovora ATCC 15580T(U80195)

Erwinia tasmaniensis Et1/99T(AM055716)

Erwinia billingiae Eb661(AM055711)

Erwinia persicina ATCC 35998T(U80205)

Erwinia rhapontici ATCC 29283T(U80206)

100

71

53

98

91

90

85

73

83

60

77

71

77

0.005

Fig. 1 Neighbor-joining phylogenetic dendrogram based on

16S rRNA sequences showing relationships between P. ag-glomerans NBRISRM and related taxa. The numbers represent

the confidence levels from 1000 replicate bootstrap sampling.

Only the bootstrap percentages higher than 50% are shown at

branching points. Bar 0.005 substitutions per nucleotide

position

408 Antonie van Leeuwenhoek (2011) 100:405–413

123

NBRISRM was increased by 11 and 7%, respectively,

in treatments containing 2% NaCl (w/v). The addition

of 4% NaCl did not significantly changed IAA

production by NBRISRM. However, significant reduc-

tion by 45% was observed at pH 9, whereas phosphate

solubilization by NBRISRM was significantly reduced

at 4% NaCl (w/v) and pH-9 by 38 and 28%,

respectively.

Colonization and plant growth promotion

of P. agglomerans NBRISRM in maize

and chickpea rhizosphere under micro plot

conditions

Colonization of NBRISRM and heterogeneous bac-

terial population in maize and chickpea rhizospheres

under micro plot conditions were monitored. Popu-

lation of NBRISRM increased in the rhizosphere of

maize from 2.3 9 107 CFU/g root at 7 DAS to

2.22 9 108 CFU/g root on 30 DAS in non-sterilized

soil. Population of NBRISRM in chickpea rhizo-

sphere increased from 2.5 9 107 CFU/g root on 7

DAS to 2.3 9 108 CFU/g root on 30 DAS in non-

sterilized soil. After 30 DAS, colonization of

NBRISRM was 107 CFU/g rhizosphere soil, through-

out the growing season for both crops. Heterogeneous

bacterial populations during the same period were in

the range 107–109 CFU/g root in both maize and

chickpea rhizospheres. Under micro plot conditions,

NBRISRM inoculated maize and chickpea plants

showed significant increase in all plant growth

parameters as compared with un-inoculated control.

The treatment of maize with NBRISRM resulted in

significant increments by 11.2, 10.9, 11.2, 11.2, 12.1,

13.9, 11.8 and 12.5% in shoot length, shoot dry

weight, number of leaves plant-1, leaf area, inter-

nodal distance plant-1, number of cobs plant-1,

number of seeds cob-1 and weight of 100 seeds,

respectively, as compared to un-inoculated control.

NBRISRM inoculated chickpea plants have signifi-

cantly increase in shoot length, shoot dry weight,

number of pods and weight of 100 seeds by 13.5,

13.5, 12.9, 13.6%, respectively, as compared with un-

inoculated control. The plant-growth promotion abil-

ity of NBRISRM treatment in maize and chickpea

plants was also confirmed by significant increases in

macronutrients uptake. In NBRISRM treated maize

N, P and K accumulation increased by 34, 41, 19%,

respectively, whereas in chickpea by 45, 37, 33%,

respectively, compared to un-inoculated control.

Functional diversity analysis of maize

and chickpea rhizosphere

For assessing the effects of NBRISRM inoculation on

maize and chickpea rhizosphere functional diversity,

carbon source utilization patterns were used to

calculate the richness, diversity and evenness indices.

Overall substrate richness, diversity and evenness

were higher in the chickpea rhizosphere compared to

maize rhizosphere. Substrate richness were found

significantly (P = 0.05) higher in NBRISRM inocu-

lated maize and chickpea rhizosphere as compared to

their respective uninoculated control. Whereas, func-

tional diversity and evenness indices were also found

higher due to inoculation of NBRISRM compared to

uninoculated maize and chickpea rhizosphere, how-

ever, no significant differences (P = 0.05) were

observed using Waller–Duncan test (Fig. 3)

Discussion

Plant growth promoting P. agglomerans NBRISRM

was able to produce IAA and solubilize unavailable

phosphate up to some extent of high temperature,

salinity and alkalinity under in vitro conditions.

Similar to our results, earlier also many PGP strains

from Pantoea sp. were reported for phytohormone

production (Feng et al. 2006; Sergeeva et al. 2007,

Dastager et al. 2009) and phosphate solubilization

IAA

pro

duct

ion

/ P-s

olub

iliza

tion

(µg/

ml)

0

20

40

60

80

100IAA productionP-solbilization

30 0C 2% NaCl pH-937 0C 4% NaCl

Fig. 2 Indole acetic acid (IAA) production and phosphate

solubilization of P. agglomerans NBRISRM under in vitro

conditions. Error bars are the standard error of the means

(n = 3)

Antonie van Leeuwenhoek (2011) 100:405–413 409

123

(Son et al. 2006). Recently, we have reported the

exopolysacharide production and bio-film formation

in the same strain under in vitro conditions (Chauhan

and Nautiyal 2010) which clearly demonstrated that

this PGP strain has potential to perform under

different abiotically stressed environment.

Under micro-plot conditions, NBRISRM colo-

nized the rhizosphere of maize and chickpea plants

with 107–108 (CFU g-1 soil) population and com-

peted with the same titer of native heterotrophic

bacterial population throughout the growing season.

Similar to these results, earlier also we have reported

the colonization ability of P. agglomerans NBRISRM

in chickpea rhizosphere under pot culture conditions

(Chauhan and Nautiyal 2010). Inoculation of

NBRISRM has significantly improved the overall

growth of maize and chickpea. Plant growth promot-

ing abilities of Pantoea sp. has been already reported

for different crops such as rice (Feng et al. 2006;

Verma et al. 2001), wheat (Ruppel et al. 1992;

Amellal et al. 1998; Egamberdiyeva and Hoflich

2001) and cotton (Egamberdiyeva and Hoflich 2001).

Enhanced macronutrients (N, P and K) uptake was

also observed in the NBRISRM treated maize and

chickpea plants as compared to uninoculated plants.

Egamberdiyeva and Hoflich (2001) has reported

earlier that inoculation of Rhizobium trifolii R39

and P. agglomerans PF76/4 isolated from the mod-

erate German climate increased the root and shoot

growth of cotton and wheat in loamy sand soil and

resulted in significantly higher N, P and K contents of

plant (Table 1).

Carbon source utilization pattern-based functional

diversity indices were found lower in maize as

compared to chickpea rhizosphere resident micro-

flora. However, no significant differences (P = 0.5)

were observed in NBRISRM inoculated maize and

chickpea rhizosphere as compared to their respective

uninoculated controls (Table 2). Earlier also Mars-

chner et al. (2001) has reported the bacterial

community composition in the rhizosphere is affected

by a complex interaction between soil type and plant

species. One important factor for PGPR survival is

compatibility between the host plant root exudate

composition and the ability of the PGPR to utilize

those compounds (Strigul and Kravchenko 2006).

Carbon source utilization patterns by environmental

samples using Biolog Eco plate offer a relatively

faster and sensitive means of assessing the changes in

microbial functional diversity as compared to other

regular cultivable methods (Nautiyal 2009). In spite

of the various criticisms, the method remains to be

widely used to a large extent due to the ease and

speed of performance (Winding and Hendriksen

2007, Mishra and Nautiyal 2009; Nautiyal et al.

2010a, b, c). Information based on rhizosphere

microbial communities structure and their diversity

which are related to other essential processes within

the same system such as complexity, natural selec-

tion, symbiosis, parasitism, mutualism, competence,

succession or the effect of disturbances is a better

way to understand the system and for maximum

exploitation of PGPR.

Overall results conclude that the enhancement in

the maize and chickpea growth, nutrient uptake was

recorded under microplot conditions due to inocula-

tion of rhizosphere competent plant growth promot-

ing P. agglomerans NBRISRM. Moreover, functional

4

5

6

7

8

9

10

HeterotrophsNBRISRM

Time (days)0 20 40 60 80 100

Lo

g 1

0 C

FU

/g r

oo

t

4

5

6

7

8

9

A

B

Fig. 3 Survival and competence in the rhizosphere of a Zeamays and b Cicer arietinum L. by P. agglomerans NBRISRM.

Error bars are the standard error of the means (n = 6)

410 Antonie van Leeuwenhoek (2011) 100:405–413

123

diversity in maize and chickpea rhizosphere was

remained the same. Large scale multilocational field

trials are required to establish this stain as beneficial

bioinoculant application package for its further

exploitation.

Acknowledgments CSN acknowledges financial support of

the work from Task Force Council of Scientific and Industrial

Research (CSIR) grant NWP-006 is duly acknowledged. VC

would like to thank CSIR for providing her Senior Research

Fellowship.

Table 1 Effect of P. agglomerans NBRISRM on plant growth promotion and macronutrients uptake of maize and chickpea under

microplot conditions

Un-inoculated control NBRISRM treated LSD* at 5%

Maize

Shoot length (cm) 178.00 ± 13.11 199.67 ± 11.23 14.04

Dry weight shoot (g) 149.67 ± 6.02 163.17 ± 5.29 8.53

No. of leaves/plant 132.67 ± 3.92 146.00 ± 4.90 8.21

Leaf area (cm2) 11.77 ± 0.79 13.12 ± 0.62 0.98

Inter-nodal distance/plant (cm) 14.67 ± 0.68 16.77 ± 0.88 1.11

No. of cobs/plant 1.43 ± 0.22 1.99 ± 0.21 0.47

No. of seeds/cob 465.92 ± 13.87 549.17 ± 18.17 32.23

Weight of 100 seeds (g) 20.37 ± 0.45 25.50 ± 0.65 1.68

N uptake (mg/g tissue) 14.44 ± 1.22 19.32 ± 1.71 3.77

P uptake (mg/g tissue) 1.76 ± 0.11 2.48 ± 0.13 1.07

K uptake (mg/g tissue) 1.65 ± 0.09 1.96 ± 0.10 0.96

Chickpea

Shoot length (cm) 19.44 ± 1.11 26.22 ± 1.23 6.4

Dry weight shoot (g) 1.32 ± 0.02 1.79 ± 0.05 0.33

No. of pods/plant 23.48 ± 1.80 30.44 ± 2.11 4.66

Weight of 100 seeds (g) 12.22 ± 0.90 16.66 ± 1.22 3.55

N uptake (mg/g tissue) 103.20 ± 11.2 149.50 ± 13.4 10.93

P uptake (mg/g tissue) 0.24 ± 0.05 0.33 ± 0.08 0.69

K uptake (mg/g tissue) 0.21 ± 0.04 0.28 ± 0.05 0.54

Data were recorded after 90 days of sowing and results are shown as mean ± standard error (n = 12)

Table 2 Substrate richness, diversity and evenness indices of maize and chickpea rhizosphere treated P. agglomerans NBRISRM

based on substrate utilization pattern Biolog Eco plates containing 31 different carbon sources

Treatment Substrate

richness

McIntosh diversity

index

McIntosh

evenness

Shannon diversity

index

Shannon

evenness

Simpson diversity

index

Maize

Un-

inoculated

24.17 ± 1.13ab 0.928 ± 0.001a 0.945 ± 0.038a 3.013 ± 0.015a 0.881 ± 0.001a 0.974 ± 0.004a

Inoculated 28.67 ± 1.33a 0.931 ± 0.001a 0.949 ± 0.001a 3.019 ± 0.002a 0.884 ± 0.001a 0.980 ± 0.002a

Chickpea

Un-

inoculated

25.48 ± 1.67b 0.946 ± 0.001b 0.956 ± 0.001b 3.215 ± 0.004b 0.924 ± 0.001b 0.989 ± 0.001b

Inoculated 29.44 ± 1.20a 0.952 ± 0.004b 0.958 ± 0.001b 3.220 ± 0.032b 0.928 ± 0.002b 0.993 ± 0.001b

Plants were harvested after 90 days of sowing. Results are shown as mean ± standard error (n = 3)

Different letters showing significant difference at P = 0.05 using Waller–Duncan test

Antonie van Leeuwenhoek (2011) 100:405–413 411

123

Conflict of interest The authors have declared no conflict of

interest.

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