Dual inoculation of salt tolerant Bradyrhizobium and Glomus mosseae for improvement of Vigna radiata L. cultivation in saline areas of West Bengal, India

doi:10.4236/as.2011.24053

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Vol.2, No.4, 413-423 (2011)

doi:10.4236/as.2011.24053

Agricultural Scienc es

Dual inoculation of salt tolerant Bradyrhizobium and

Glomus mosseae for improvement of Vigna radiata L.

cultivation in saline areas of West Bengal, India

Nicky Singh*, Nirmalendu Samajpati, Amal Kanti Paul

Department of Botany, University of Calcutta, Kolkata, West Bengal, India; *Corresponding Author: nickysinghraj@gmail.com

Received 7 September 2011; revised 19 October 2011; accepted 27 October 2011.

ABSTRACT

This study is aimed as to evaluate the interac-

tion between salt tolerant Bradyrhizobium sp.

and Glomus mosseae in the rhizosphere of

legume crop Vigna radiata L. under pot culture

and field conditions in different saline zones of

West Bengal, India. Bradyrhizobium sp. when

inoculated alone showed marked increase in

number of nodules, root and shoot length, total

plant biomass, arbuscular mycorrhizal fungal

(AMF) colonization and population etc. when

compared with plants inoculated only with AMF.

However, when used in combination, the in-

oculants showed marked change in the above

mentioned parameters over single inoculation

of both salt tolerant AM fungi and Bradyrhizo-

bium. These results suggest that AMF along

with Bradyrhizobium can greatly help in estab-

lishment of V. radiata L. cultivation in the saline

soils of West Bengal, India. The increased pro-

duction of the legume crop could also lead to

further benefit of the poor farmers by up lifting

their socio-economic conditions with the net

profit achieved by cultivating this crop in saline

stress condition of West Bengal as a second

crop during rabi season.

Keywords: Vigna radiat a L.; Arbuscular

Mycorrhizal Fungi; Bradyrhizobium; Salinity;

Glomus m o sseae

1. INTRODUCTION

Salinization and nutrient depletion are serious and

growing problems of agricultural land in different parts

of the world [1,2]. Soil salinity inhibits plant growth by

reducing the ability of the plant water uptake and ion-

excess, which affects the cellular metabolism [3,4].

Moreover, it induces nutritional imbalance in plants and

thereby reduces the yield of many crops. This ranges

from a slight crop loss to complete crop failure de-

pending on the type of crop and severity of the salinity

problem. Though several treatments and management

practices are available to reduce salt levels in the soil,

there are situations where it is either impossible or too

costly to attain desirably low soil salinity levels. Recla-

mation and management of such saline soils are there-

fore essential to meet the surplus need of food for ever

increasing population of developing countries.

In India, coastal saline soils are spreaded over an area

of approximately 3.1 million hectare including eight

coastal states [5]. Among these, the state of West Bengal

has the highest area (820 × 103 hectare) of coastal saline

land encompassing five districts namely North 24-Par-

ganas, South 24-Parganas, Haora, East Medinipur and

West Medinipur.

The salinity response of legumes in general varies

greatly depending on factors like climatic conditions, soil

properties, salt tolerance and the stages of crop growth

[6-8]. Successful cultivation of legumes can be achieved

by the selection and/or development of a salt-tolerant

legume/Rhizobium combination although high salinities

are known to affect rhizobial activities. The legume-

Rhizobium symbioses and nodule formation in legumes

are more sensitive to salt or osmotic stress. Salinity is

reported to affect the infection process by inhibiting root

hair growth and decreasing the number of nodule per

plant and the amount of N2 fixed per unit weight of nod-

ules. These cause a decrease in the yield of leguminous

crops in saline soils due to the lack of the successful

symbiosis.

In addition, mutualistic association of arbuscular my-

corrhizal fungi (AMF) also improves plant salinity tol-

erance by virtue of the recognized role of mycorrhizae in

plant growth performance [9]. On the contrary, my-

corrhizal infection can be suppressed by high salinity

depending on the species or the origin of the fungus [10].

However, a synergistic association of arbuscular my-

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

414

corrhizal fungi and rhizobia with leguminous crops has

been found to cause an increase in nodulation, nitrogen

fixation as well as growth and yield of legumes. Such an

effective improvement of plant growth varies with the

host genotype. Therefore, the development of host spe-

cific, salinity tolerant rhizobia—AMF symbiosis could

be an effective approach for the successful cultivation of

legume crops in the rabi season as a second crop in the

saline tracts.

So far, the response of the pulse crop mung (Vigna ra-

diata L.) to dual inoculation of Rhizob ium—arbuscular

mycorrhizal fungus and their cultivation under salt

stressed conditions have not yet been evaluated under

the agro climatic conditions of West Bengal, India. The

present investigation is, therefore, an attempt to inocu-

late Vigna radiata L. with salinity-tolerant rhizobia and

AM fungi and to evaluate growth and yield performance

of the crop in saline belts of West Bengal which is char-

acterized by mono-crop aman rice cultivation during the

kharif season (June-November) only. Cultivation of V.

radiata L. in these fallow lands as a second crop during

the rabi season has also been attempted to improve the

socio-economic status of the cultivators of saline zones

of West Bengal, India.

2. MATERIALS AND METHODS

2.1. Source of Legume Cultivar and

Microbial Culture

Vigna radiata L., cultivar B-1, the salt tolerant legume

was selected during the course of screening of pulse crops

for tolerance to salt stress. Seeds of this salt tolerant cul-

tivar were obtained from the Oil and Pulse Seed Re-

search Station, Department of Agriculture, Government

of West Bengal, Behrampore, Murshidabad, India and

used throughout the present study.

Salt tolerant, streptomycin resistant Bradyrhizobium

CAN-11 was isolated from root nodules of salt tolerant

cultivar B-1 of V. radiata L. following the method of [11].

The strain was maintained by regular sub culturing on

slopes of yeast extract mannitol agar medium. Glomus

mosseae (BAS-I) tolerating NaCl was isolated from sa-

line tracts of West Bengal, India and multiplied in open

pot culture of Zea may s L. following the method.

2.2. Inoculum Development

The streptomycin resistant, salt tolerant Bradyrhizo-

bium sp. (CAN-11) was grown in yeast extract mannitol

agar medium containing 400 μg/ml of streptomycin 48 -

96 h and harvested by centrifugation at 10,000× g for 10

min. Inoculum of salt tolerant mycorrhizal complex

Glomus mosseae (BAS-I) was prepared in an open-pot

culture of Zea mays L. The soil of the pot was inoculated

with spores, mycelia of G. mosseae (BAS-I) and pieces

of infected Zea mays roots. After 50 days of growth of

Zea mays, the soil of the pots was taken out, properly

dried in an open air and stored in polypackets for future

use.

2.3. Cultivation in Earthen Pots

The earthen ware pots (15 cm dia.) filled with 2 kg sa-

line soils of respective saline zones of West Bengal and

autoclaved twice at 121˚C for 1 h. Seeds of V. radiata L.

cultivar B-1 were surface sterilized in ethanol: H2O2 (1:1)

for 3 min, washed with sterile distilled water and germi-

nated. Five healthy germinated seeds per pot were sown

during March/April and the pots were covered with cel-

lophane topped paper cylinder. After two weeks, the tops

were removed and the plants were transferred to glass

house maintained with a day/night temperature of ap-

proximately 28˚C/20˚C, 75% - 85% relative humidity

(RH) and a photoperiod of 12 - 13 h. After 7 days, each

pot was inoculated with 1 mL of bacterial suspension

(108 cells mL–1) [12] and/or with 10 g of mycorrhizal

inoculum (50 propagules g–1 of soil) [13].

Four combinations of inoculation were used: 1) Bra-

dyrhizobium (CAN-11), 2) Glomus mosseae (BAS-I), 3)

Bradyrhizobium (CAN-11) + Glomus mosseae (BAS-I)

and 4) uninoculated pots served as control. Five replica-

tions per inoculation treatment were prepared. The plants

were watered at a regular interval of 2 days. Pot soils

were also supplemented with a basal nutrient solution

containing (in mol·m–3):CaCl2, 0.25; KCl, 0.15; K2HPO4,

0.06; MgSO4, 0.25; FeEDTA. 0.12; and (in mol·m–3):

H3BO4, 11.5; MgSO4, 0.9; ZnSO4, 0.2; CuSO4, 0.07; and

H2MoO4, 0.3. During experiments with AM fungi, P was

omitted. Plants were harvested during May/June and the

growth parameters were evaluated.

2.4. Cultivation in Field Plots

Field experiments were conducted in random block

design (RBD) with three replications. The plot size was

5 m × 4 m with spacing of 30 cm × 10 cm between rows

and crop. Seeds were inoculated with salt tolerant Bra-

dyrhizobium (CAN-11) and Glomus mosseae (BAS-I)

inoculants by mixing thoroughly with the slurry of in-

oculants. Prior to sowing of seeds, field soil was pro-

vided with fresh culture of mixed inoculants on the sur-

face layer (2 - 3 cm deep) and mixed thoroughly with

ladder ploughing. The fertilizer was added at the rate of

N:K:P at 20:60:20 kg/ha, but during AMF experiments P

was omitted.

Seeds were sown in March/April by broadcasting at

the rate of 15 kg/ha. Three irrigations were given: first at

pre-sowing, second at flowering/ pod initiations and the

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

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third one during grain setting stage. Weeding was done

regularly as and when required and the crop was har-

vested during May/June.

2.5. Estimation of Plat Growth

Plants were harvested after 90 days of growth. The

growth of V. radiata L. was estimated by measuring the

length of the plant aerial part and the biomass produced

by shoots and roots. Shoots and roots were dried sepa-

rately at 80˚C for 48h and their dry weights were re-

corded.

Relative growth rate (RGR) for total plant (RGRt),

shoot (RGRs), and root (RGRr) were calculated on the

basis of days of growth and expressed as dry weight of

plants using the following formula:



In In

itot

RGRWtWtt t o



where i = variable used (total plant shoot or root dry wt)

to measure RGR (day–1); tt = is the total period of growth

(day) from germination; to = is the initial period of

growth of 45 days from germination; Wtt = is plant dry

weight (total shoot or root) at the end of the experiment-

tal period (90 day); Wto = is plant dry weight at the be-

ginning of the experimental period (45 day).

2.6. Root Colonization and Spore Count of

AM Fungi

Root colonization by AM fungi was studied following

the method as described by [14] Colonization of AM

fungi was determined by evaluating percentage of root

segments containing arbuscules and Vesicles using grid-

line intercept method of [15].

AM fungal spores were recovered from rhizospheric

soil by wet sieving followed by sucrose gradient cen-

trifugation method of [16]. Spores were counted under

×35 magnification in a dissecting microscope and the

density (SD) was expressed as the number of spore’s g–1

dry soil.

2.7. Socioeconomic Study

A door to door survey on social stratification, popula-

tion size and annual income of families in some selected

villages of Kakdwip areas of South 24-Parganas were

conducted.

2.8. Statistical Analysis

All data were subjected to analysis of variance (ANOVA)

followed by Duncan’s multiple range list [17]. Percent-

age data were arcsine—transformed before a statistical

analysis.

3. RESULTS

In pot culture experiments with saline soils from

South and North 24-Parganas and East Medinipur dis-

tricts of West Bengal growth of inoculated V. radiata L.

cultivar B-1 was in general higher than the non-inocu-

lated ones. When applied as single inoculum, perform-

ance of Bradyrhizobium CAN-11 was much better than

G. mosseae BAS-I. At the same time, a significant im-

provement of growth was noticed for the dual inocula-

tion of CAN-11 and BAS-I (Table 1). All the growth

parameters studied i.e. plant height, shoot and root

length, shoot and root dry/fresh weight and shoot/root

ratio showed noticeable improvement due to dual inocu-

lation. In general, growth of the crop was better in South

24-Parganas compared to North 24-Parganas and East

Medinipur districts of West Bengal, India.

The relative growth rate (RGR) for total plant (RGRt),

shoot (RGRs) and root (RGRr) were determined within a

period of 90 days and it was found maximum in North

24-Parganas during double inoculation of Bradyrhizo-

bium CAN-11 and G. mosseae BAS-I (Figure 1).

The number of nodules per plant after three months of

inoculation depended on the microsymbionts utilized.

The no. of nodules per plant varied between 29 (treat-

ment with CAN-11), 25 (treatment with BAS-I) and 34

(treatment with BAS-I + CAN-11) in North 24-Pargana

soil. In South 24-pargana soil it was maximum with 33

nodules plant–1 with treatment of BAS-I and CAN-11; E.

Medinipur has the lowest i.e. 29 nodules plant–1 with

treatment of BAS-I and CAN-11 (Figure 2) Fresh and

dry weights of nodules were in relevance with number of

nodules.

The level of mycorrhizal infection in roots of V. ra -

diata L. cultivar B-I appeared to be less sensitive to

NaCl and the mycorrhizal infection was maximum in all

three districts of West Bengal with double inoculation

(BAS-I + CAN-11) when compared to single inoculation

by BAS-I or CAN-11 (Figure 3(a)). Similarly, the AM

spore population in soil of all three districts was maxi-

mum during dual inoculation experiments. However,

highest spore population was recorded in North 24-Par-

ganas of West Bengal (Figure 3(b)).

Field trial of V. radiata L. was made under random

block design using dual inoculation of Bradyrhizobium

CAN-11 and G. mosseae BAS-I. Cultivations were con-

ducted in three different districts viz. North 24-Parganas

(Deuli, Kharampur and Saimalpur), South 24-Parganas

(Basanti, Canning and Kakdwip) and East Medinipur

(Kanthi and Tamluk) during 2005 and 2006. Growth

performance of the legume was in general superior in

South 24-Parganas than in North 24-Parganas and E.

Medinipur. In South 24-Parganas alone performance was

best in Basanti was followed by Canning and Kakdwip

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

416

Table 1. Effect of salt tolerant Bradyrhizobium CAN-11 and G. mosseae BAS-1 on the growth of Vigna radiata cv. B-1 in pot culture.

Soil inoculants

Source of soil Control (uninoculated soil)

CAN-11 BAS-I CAN-11 + BAS-I

South 24-ParganasA

Plant height (cm) 55.90 ± 0.35e 59.40 ± 0.34e 58.90 ± 0.32ab 62.04 ± 0.30e

Plant biomass, dry (g) 3.20 ± 0.12b 3.46 ± 0.10bc 3.40 ± 0.12d 3.54 ± 0.14d

Shoot length (cm) 44.80 ± 0.24d 46.80 ± 0.12c 46.20 ± 0.36e 49.80 ± 0.42f

Shoot weight, dry (g) 2.44 ± 0.10a 2.88 ± 0.10d 2.81 ± 0.12c 2.98 ± 0.16b

Root length (cm) 11.10 ± 0.12d 12.60 ± 0.20e 12.42 ± 0.14d 13.10 ± 0.20d

Root weight, dry (g) 0.76 ± 0.06f 0.86 ± 0.04b 0.82 ± 0.04a 0.94 ± 0.08c

Shoot/Root ratio (length) 4.03 ± 0.14c 3.71 ± 0.08d 3.72 ± 0.12b 3.80 ± 0.12b

Yield of grains (g) 1.84 ± 0.14e 2.89 ± 0.30d 2.71 ± 0.22a 3.70 ± 0.24c

North 24-ParganasB

Plant height (cm) 58.00 ± 0.34d 60.60 ± 0.36a 59.04 ± 0.28a 63.26 ± 0.40b

Plant biomass, dry (g) 3.58 ± 0.08c 3.77 ± 0.12d 3.64 ± 0.12d 4.14 ± 0.06c

Shoot length (cm) 46.60 ± 0.42bc 47.40 ± 0.40b 47.20 ± 0.48c 49.40 ± 0.42e

Shoot weight, dry (g) 2.64 ± 0.08d 2.67 ± 0.14d 2.66 ± 0.12e 2.86 ± 0.12a

Root length (cm) 11.40 ± 0.12ef 13.20 ± 0.24ef 12.84 ± 0.18d 13.86 ± 0.30b

Root weight, dry (g) 0.94 ± 0.04d 1.10 ± 0.04c 0.98 ± 0.02b 1.28 ± 0.08cd

Shoot/Root ratio (length) 4.88 ± 0.14c 3.59 ± 0.10d 3.67 ± 0.06c 3.56 ± 0.12d

Yield of grains (g) 2.24 ± 0.06d 3.89 ± 0.08a 3.09 ± 0.06d 4.50 ± 0.10a

East MedinipurC

Plant height (cm) 68.30 ± 0.48e 71.60 ± 0.52a 70.50 ± 0.48a 75.00 ± 0.54c

Plant biomass, dry (g) 2.10 ± 0.12b 2.54 ± 0.12d 2.28 ± 0.14c 2.86 ± 0.16e

Shoot length (cm) 53.60 ± 0.34d 55.10 ± 0.32f 54.40 ± 0.36e 57.20 ± 0.32b

Shoot weight, dry (g) 1.78 ± 0.18b 2.10 ± 0.16a 1.82 ± 0.14d 2.34 ± 0.16a

Root length (cm) 14.70 ± 0.22d 16.50 ± 0.28b 16.10 ± 0.24b 17.80 ± 0.28d

Root weight, dry (g) 0.42 ± 0.06f 0.49 ± 0.08c 0.46 ± 0.06c 0.52 ± 0.08c

Shoot/Root ratio (length) 3.64 ± 0.12c 3.64 ± 0.14d 3.37 ± 0.10a 3.21 ± 0.14d

Yield of grains (g) 3.16 ± 0.32d 4.44 ± 0.32d 3.61 ± 0.36c 5.21 ± 0.34b

Soils of experimental sites were thoroughly mixed in equal proportion and used in pots. Soil salinity: A = 7.5 (dSm−1), B = 6.5 (dSm−1) and C = 7.2 (dSm−1).

a,b,c,d,e,fMean data in each vertical row followed by different letters are significantly different (P ≤ 0.05) as per Duncan's Multiple Range Test (n = 5). Values

indicate mean of five replicates ± S E.

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

S 24-PN 24-PE. Med.

Source of soil

RGR

(day

-1

)

Control CAN 11

BAS ICAN 11 + BAS I

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

S 24-PN 24-PE. Med.

Source of soil

RGR

(day

-1

)

Control CAN 11

BAS ICAN 11 + BAS I

(a) (b)

Openly accessible at

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

417417

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

S 24-PN 24-PE. Med.

Source of soil

RGR

(day

-1

)

Control CAN 11

BAS ICAN 11 + BAS I

(c)

Figure 1. Relative growth rate of total plant RGRt (a), total shoot RGRs (b) and total root RGRr (c) of V. radiata cv. B-1 inoculated

with Bradyrhizobium CAN-11 and or G. mosseae BAS- I in pot culture. S 24-P = South 24-Parganas, N 24-P = North 24-Parganas

and E. Med = East Medinipur.

S 24-PN 24-PE. Med.

Source of soil

No of nodules plant

-1

Control CAN 11

BAS ICAN 11 + BAS I

S 24-PN 24-PE. Med.

Source of soil

Wt. of nodules, (g) fresh plant

-1

Control CAN 11

BAS ICAN 11 + BAS I

(a) (b)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

S 24-PN 24-PE. Med.

Source of soil

Wt. of nodules, (g) dry plant

-1

Control CAN 11

BAS ICAN 11 + BAS I

(c)

Figure 2. Effect of salt tolerant Bradyrhizobium CAN-11 and G. mosseae BAS-I inoculation on number of nodules plant–1 (a), fresh

wt. of nodules plant–1 (b) and dry wt of nodules plant–1 (c) of V. radiata cv. B-1 in pot culture. S 24-P = South 24-Parganas, N 24-P =

North 24-Parganas and E. Med = East Medinipur.

(Table 2). In Table 3 we find that growth was maximum

in Kharampur followed by Deuli and Saimalpur in North

24-Parganas. Similarly in Table 4 Tamluk was better than

Kanthi of East Medinipur districts.

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

418

S 24-PN 24-PE. Med.

Source of soil

Mycorrhizal infection, %

Control CAN 11

BAS ICAN 11 + BAS I

(a)

100

120

S 24-PN 24-PE. Med.

Source of soil

AMF spores 100 g

soil

Control CAN 11

BAS ICAN 11 + BAS I

(b)

Figure 3. Incidence of mycorrhizal infection and population of AMF spores during growth of V. radiata cv. B-1 inoculated with

Bradyrhizobium CAN-11 and or G. mosseae BAS-I in pot culture of S 24-P = South 24-Parganas, N 24-P = North 24-Parganas and E.

Med = East Medinipur.

Table 2. Effect of inoculation of salt tolerant Bradyrhizobium CAN -11 and salt tolernt G. mosseae BAS-I on the growth of V. radiata

cv. B-1 in different experimental fields of South 24-Parganas during 2005 and 2006.

Experimental fields of South 24-Parganas

Basanti Canning Kakdwip

Growth characteristics/plant−1

2005 2006 2005 2006 2005 2006

Plant height (cm) 69.00 ± 4.50a70.50 ± 4.52c68.60 ± 4.98a69.40 ± 4.46a64.00 ± 4.42d 64.80 ± 4.44a

Total plant biomass (g), fresh 20.80 ± 2.36c21.20 ± 2.34b19.80 ± 2.32b20.90 ± 2.36c20.10 ± 2.32e 20.40 ± 2.28b

Total plant biomass (g), dry 4.30 ± 0.24d 4.20 ± 0.26e 4.16 ± 0.18c 4.32 ± 0.16d 4.14 ± 0.20f 4.18 ± 0.22c

Shoot length (cm) 56.20 ± 3.48e56.80 ± 3.46d55.40 ± 3.50d56.30 ± 3.54f52.10 ± 3.44b 52.40 ± 3.46d

Shoot weight (g), fresh 16.12 ± 2.20b16.30 ± 2.22a15.90 ± 2.18f16.10 ± 2.16b15.60 ± 2.20e 15.62 ± 2.28e

Shoot weight (g), dry 3.28 ± 0.12a 3.31 ± 0.10b 3.10 ± 0.14a 3.12 ± 0.12c 3.06 ± 0.14d 3.07 ± 0.16b

Root length (cm) 12.80 ± 1.26c13.70 ± 1.28e13.20 ± 1.24b13.10 ± 1.24d11.90 ± 1.22e 12.40 ± 1.20d

Root weight (g), fresh 4.68 ± 0.10d 4.90 ± 0.18f 3.90 ± 0.16d 4.80 ± 0.18e 4.50 ± 0.20b 4.78 ± 0.22a

Root weight (g), dry 1.02 ± 0.08a 0.89 ± 0.06b 1.06 ± 0.08e 1.20 ± 0.10a 1.08 ± 0.08cd 1.11 ± 0.14c

Shoot/Root ratio (length) 4.39 ± 2.76b 4.14 ± 2.70c 4.19 ± 2.82c 4.29 ± 2.85c 4.37 ± 2.81d 4.22 ± 2.88b

No. of branches 4.92 ± 0.80c 4.96 ± 1.22d 4.84 ± 1.24d 4.90 ± 1.24b 4.70 ± 1.18de 4.74 ± 1.22d

No. of pods 17.60 ± 2.32d18.60 ± 2.32e16.80 ± 2.34b17.40 ± 2.36d16.60 ± 2.38ef 17.00 ± 2.32e

No. of seeds pod–1 8.40 ± 1.24e 8.50 ± 1.26a 6.80 ± 1.20a 7.20 ± 1.18c 6.60 ± 1.20a 7.40 ± 1.18b

Weight of seeds (100 nos.) 3.18 ± 0.12a 3.20 ± 0.12b 3.10 ± 0.14cd 3.12 ± 0.16a 3.12 ± 0.12bc 3.12 ± 0.14c

No. of nodule 34.20 ± 4.42bc 35.10 ± 3.42c32.20 ± 3.44d33.40 ± 3.46b31.80 ± 3.38d 32.60 ± 3.34d

Weight of nodules (g), fresh 7.10 ± 1.24c 7.12 ± 1.22d 6.98 ± 1.32ef 6.98 ± 1.34c 6.60 ± 1.20b 6.70 ± 1.28e

Weight of nodules (g), dry 0.34 ± 0.06cd 0.34 ± 0.60f 0.30 ± 0.08f 0.30 ± 0.08d 0.28 ± 0.08c 0.29 ± 0.06a

Population of AMF (spores100 g–1 soil) 106 ± 4.2e 108 ± 2.12a 98 ± 4.46d 98 ± 1.22e 96 ± 4.18a 98 ± 4.14b

Colonization of roots (%) 82 ± 3.8b 82 ± 3.62c 68 ± 2.86cd 70 ± 4.54f 66 ± 3.1d 70 ± 4.26c

Days of maturity 74 ± 5d 73 ± 4b 76 ± 4d 73 ± 5a 78 ± 4b 77 ± 5d

Yield of grain (kg·ha–1) 560 ± 21c 568 ± 20d 570 ± 25a 575 ± 18b 540 ± 14e 548 ± 18e

RGRt (day–1) 0.076 ± 0.002d0.078 ± 0.002e0.066 ± 0.002c0.068 ± 0.002c 0.066 ± 0.002a 0.067 ± 0.003c

RGRs (day–1) 0.074 ± 0.002b0.076 ± 0.002c0.066 ± 0.002e0.068 ± 0.002e 0.066 ± 0.002d 0.068 ± 0.002b

RGRr (day–1) 0.074 ± 0.003a0.075 ± 0.002d0.066 ± 0.002d0.068 ± 0.002d 0.064 ± 0.002c 0.068 ± 0.002a

Values indicate mean of five replicates ± SE. a,b,c,d,e,fMean data in each vertical row followed by different letters are significantly different (P ≤ 0.05) as per

Duncan’s Multiple Range Test (n = 5). RGRt, RGRs and RGRr are Relative growth rate of total plant, shoot and root respectively determined within a period of

growth of 45 days.

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

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Table 3 . Effect of inoculation of salt tolerant Bradyrhizobium CAN-11 and G. mosseae BAS-I on the growth of V. radiata cv. B-1 in

different experimental fields of North 24-Parganas during 2005 and 2006.

Experimental fields of North 24-Parganas

Deuli Kharampur Saimalpur

Growth characteristics/plant−1

2005 2006 2005 2006 2005 2006

Plant height (cm) 66.80 ± 4.62a 67.20 ± 4.58c68.10 ± 4.48c68.70 ± 4.52c64.40 ± 4.60a 66.10 ± 4.64a

Total plant biomass (g), fresh 23.20 ± 2.28b23.60 ± 2.26d24.50 ± 2.30d24.90 ± 2.32d22.60 ± 0.30b 23.00 ± 2.34b

Total plant biomass (g), dry 4.42 ± 0.18c 4.43 ± 0.16a 4.50 ± 0.26f 4.52 ± 0.22a 3.92 ± 0.18d 4.24 ± 0.24d

Shoot length (cm) 52.80 ± 3.60d53.10 ± 3.58b53.70 ± 3.62e54.10 ± 3.56b51.10 ± 3.60c 52.40 ± 3.62e

Shoot weight (g), fresh 16.70 ± 2.28e 16.90 ± 2.36c17.00 ± 2.34a17.50 ± 2.28c15.60 ± 2.30e 15.80 ± 2.32a

Shoot weight (g), dry 3.10 ± 0.16bc 3.12 ± 0.18d 3.14 ± 0.18b 3.28 ± 0.16d 2.90 ± 0.18a 2.92 ± 0.20b

Root length (cm) 14.00 ± 1.38c 14.10 ± 1.32f14.40 ± 2.34c14.60 ± 1.36b13.30 ± 1.32b 13.70 ± 1.38c

Root weight (g), fresh 6.80 ± 0.68d 6.70 ± 0.64e 7.50 ± 0.60d 7.40 ± 0.64a 7.00 ± 0.66d 7.20 ± 0.68d

Root weight (g), dry 1.32 ± 0.28ef 1.31 ± 0.30d 1.36 ± 0.32e 1.24 ± 0.34e 1.02 ± 0.18b 1.32 ± 0.18e

Shoot/Root ratio (length) 3.77 ± 2.60bf 3.76 ± 2.71b 3.72 ± 1.54a 3.70 ± 2.61b 3.84 ± 2.72c 3.82 ± 2.62b

No. of branches 5.40 ± 1.18a 5.60 ± 0.96c 5.70 ± 0.88b 5.80 ± 1.40c 4.90 ± 1.34b 5.10 ± 1.42c

No. of pods 16.00 ± 2.10c 18.50 ± 2.24a19.00 ± 2.78c19.80 ± 3.10d15.60 ± 2.36d 15.90 ± 2.40d

No. of seeds pod–1 8.10 ± 1.42d 8.30 ± 1.46e 8.50 ± 1.46d 8.70 ± 1.38ae 6.80 ± 1.32a 6.90 ± 1.40a

Weight of seeds (100 nos.) 4.10 ± 0.24e 4.20 ± 0.26d 4.40 ± 0.28e 4.70 ± 0.26e 3.70 ± 0.20b 3.90 ± 0.32b

No. of nodule 37.20 ± 3.62b38.40 ± 4.12c39.80 ± 3.24a40.40 ± 4.50bc 35.40 ± 3.62c 35.90 ± 3.72d

Weight of nodules (g), fresh 7.10 ± 1.50d 7.12 ± 1.62b 7.22 ± 1.58b 7.24 ± 1.38c 6.84 ± 1.48d 6.87 ± 1.54e

Weight of nodules (g), dry 0.36 ± 0.02a 0.38 ± 0.04ac 0.39 ± 0.03c 0.40 ± 0.04cd 0.30 ± 0.02e 0.32 ± 0.04f

Population of AMF (spores100 g–1 soil) 92 ± 5.4c 94 ± 5.2c 95 ± 4.8d 95 ± 4.2ef 86 ± 5.4b 88 ± 5.2c

Colonization of roots (%) 68 ± 4.4b 70 ± 4.5d 75 ± 4.4e 77 ± 4.6f 66 ± 3.8c 68 ± 4d

Days of maturity 69 ± 4.4c 72 ± 4.5e 73 ± 4.8a 75 ± 4.2a 68 ± 3.4d 68 ± 4a

Yield of grain (kg·ha–1) 580 ± 18d 588 ± 20f 594 ± 14b 598 ± 20b 612 ± 22e 622 ± 24b

RGRt (day–-1) 0.076 ± 0.002e0.078 ± 0.002c0.072 ± 0.002c0.074 ± 0.002c0.066 ± 0.002d 0.068 ± 0.002c

RGRs (day–1) 0.076 ± 0.002b0.078 ± 0.002d0.072 ± 0.003e0.074 ± 0.002e0.064 ± 0.002a 0.068 ± 0.002d

RGRr (day–1) 0.074 ± 0.002a0.076 ± 0.002a0.072 ± 0.002d0.074 ± 0.002d0.066 ± 0.002c 0.068 ± 0.002a

Values indicate mean of five replicates ± SE. a,b,c,d,e,fMean data in each vertical row followed by different letters are significantly different (P ≤ 0.05) as per

Duncan’s Multiple Range Test (n = 5). RGRt, RGRs and RGRr are Relative growth rate of total plant, shoot and root respectively determined within a period of

growth of 45 days.

Parallel to this grain yield was maximum in Basanti

followed by Canning and Kakdwip of South 24-Parga-

nas (Table 2). Further it also revealed that maximum

amount of grain (Table 3 ) was recovered in Saimalpur

on North 24-Parganas whereas Kanthi had more yield

(Table 4) than in Tamluk of East Medinipur districts.

Nodulation characteristics of V. radiata L. including

the no. of nodules dry and fresh weight per plant after

dual inoculation increases in all three districts i.e. South

and North 24-Parganas and East Medinipur. Moreover,

such improved features were better expressed in 2006

than in 2005 (Tables 2-4).

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

420

Table 4. Effect of inoculation of salt tolerant Bradyrhizobium CAN-11 and G. mosseae BAS-I on the growth of V. radiata cv. B-1 in

different experimental fields of East Medinipur during 2005 and 2006.

Experimental fields of East Medinipur

Kanthi Tamluk

Growth characteristics/plant−1

2005 2006 2005 2006

Plant height (cm) 64.2 ± 5.2a 65.6 ± 5.18b 66.4 ± 5.30c 67.4 ± 5.42a

Total plant biomass (g), fresh 19.8 ± 2.16c 20.2 ± 2.42c 20.8 ± 2.14d 21.4 ± 2.32d

Total plant biomass (g) Dry 3.60 ± 0.62d 3.61 ± 0.50d 3.94 ± 0.56a 3.92 ± 0.58b

Shoot length (cm) 49.8 ± 3.60a 51.0 ± 4.24e 52.1 ± 3.84b 52.8 ± 4.10c

Shoot weight (g), fresh 16.6 ± 1.82b 16.9 ± 1.28a 17.1 ± 1.64c 17.6 ± 1.84d

Shoot weight (g), dry 2.99 ± 0.42c 3.1 ± 0.48b 3.3 ± 0.52d 3.2 ± 0.59e

Root length (cm) 14.4 ± 1.64d 14.6 ± 1.62d 14.7 ± 1.84e 14.9 ± 1.82f

Root weight (g), fresh 3.20 ± 0.48a 3.3 ± 0.54c 3.7 ± 0.56c 3.8 ± 0.48b

Root weight (g), dry 0.61 ± 0.06b 0.63 ± 0.04a 0.64 ± 0.04d 0.72 ± 0.06c

Shoot/Root ratio (length) 3.45 ± 2.19c 3.49 ± 2.61b 3.64 ± 2.08a 3.61 ± 2.25d

No. of branches 4.84 ± 0.68d 4.86 ± 0.64d 4.92 ± 0.48b 4.98 ± 0.42e

No. of pods 21.2 ± 2.18e 22.4 ± 2.42e 22.8 ± 2.42c 23.1 ± 2.46f

No. of seeds pod–1 7.00 ± 0.86a 7.1 ± 0.82d 6.8 ± 0.90d 6.9 ± 0.86d

Weight of seeds (100 nos.) 4.22 ± 0.58b 4.23 ± 0.46b 4.24 ± 0.38a 4.24 ± 0.44e

No. of nodule 34.4 ± 3.20c 35.2 ± 3.84c 33.8 ± 3.68b 34.1 ± 3.54c

Weight of nodules (g), fresh 6.88 ± 0.86d 6.91 ± 0.82d 6.94 ± 0.92c 6.98 ± 0.94d

Weight of nodules (g), dry 0.28 ± 0.02e 0.29 ± 0.04de 0.30 ± 0.06d 0.31 ± 0.06a

Population of AMF (spores 100g–1 soil) 88 ± 6.12b 92 ± 6.28ef 90 ± 6.40e 94 ± 6.48b

Colonization of roots (%) 72 ± 4.80a 76 ± 5.26b 74 ± 5.24d 78 ± 5.84c

Days of maturity 78 ± 4cd 79 ± 3.9c 69 ± 5e 70 ± 5.0d

Yield of grain (kg·ha–1) 590 ± 20d 598 ± 12d 586 ± 22d 594 ± 24a

RGRt (day–1) 0.076 ± 0.002e 0.078 ± 0.002e 0.076 ± 0.002a 0.078 ± 0.004e

RGRs (day–1) 0.076 ± 0.002c 0.076 ± 0.002c 0.074 ± 0.004b 0.078 ± 0.002f

RGRr (day–-1) 0.074 ± 0.002b 0.076 ± 0.002a 0.076 ± 0.003c 0.078 ± 0.003c

Values indicate mean of five replicates ± SE. a,b,c,d,e,fMean data in each vertical row followed by different letters are significantly different (P ≤ 0.05) as per

Duncan’s Multiple Range Test (n = 5). RGRt, RGRs and RGRr are Relative growth rate of total plant, shoot and root respectively determined within a period of

growth of 45 days.

Table 5. Distribution of household according to annual income from present monocrop farming systems and introduced legume cul-

tivation as second crop.

Monocrop farming systems Legume cultivation as second crop

Village

No. of household Annual income % per householdNo. of householdAnnual income % per household

Gabbani 168 ≤15,000 80.00 - ≥15,000 Nil

31 15,000 to 50,000 14.76 190 15,000 to 50,000 90.48

11 50,000 to100,000 5.23 20 50,000 to 100,000 9.52

Barbari 131 ≤15,000 77.05 - ≥15,000 Nil

33 15,000 to 50,000 19.41 160 15,000 to 50,000 94.12

6 50,000 to 100,000 3.52 10 50,000 to 100,000 5.82

Villages: Gabbani and Barbari are from Canning district of South 24-Parganas, West Bengal.

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

421421

Table 6. The cost benefit ratio of cultivation of mung (V. radiata cv.B-1) in the farmers field.

V. radiata cv.B-1

Non-inoculated Inoculated

Particulars

(Rs.) (Rs.)

Land preparation 2100 2100

Sowing of seeds 700 700

Seed treatment 750 625

Cost of AM + Rhizobia inoculum Nil 250

Intercultural practices 1400 1400

Fertilizer (Basal dose N:P:K) 1400 1400

Plant protection chemicals 980 980

Harvesting 700 700

Threshing & Cleaning 980 980

Total cost 9010 9135

Yield/hectare 750 Kg 825 Kg

Total sell @ 25/Kg (grain) 18750 20625

Net profit 9740 11490

The level of mycorrhizal infection and density of AM

spores in soil were better represented in the 2nd year ir-

respective of the localities. However, it was maximum in

East Medinipur district when compared to South and

North 24-Parganas of West Bengal, India.

During the course of socio-economic study, a door to

door survey was conducted over 210 and 170 families of

Gabbani and Barbari villages of South 24-Parganas with

a total population of 1695 and 1500 respectively. As the

area is mono crop rice area, 77% - 80% of household

showed an average earning of Rs. 15,000 per annum,

while only 3% - 5% could have earned Rs. 50,000 -

100,000 per annum (Table 5).

In an attempt to introduce mung cultivation the cost

benefit ratio was calculated considering the inoculation

of AM fungus and rhizobial strains. Total cost of the

inoculated crop was more than the non-inoculated one,

but as the yield of inoculated crop was much more, it

showed a net profit of >10% over that of the uninocu-

lated one (Table 6).

When this cropping system of pulse cultivation was

introduced with salt tolerant inoculants, (rhizobium

CAN-11 and AMF BAS-1) the socio-economic condi-

tion of the household farmers changed drastically. In

both Gabbani and Barbari villages 90% - 94% household

earned up to Rs. 50,000 per annum while 5.8% - 9.5%

household could have earned up to Rs. 100,000 per an-

num (Table 5).

4. DISCUSSION

Salt salinity is known to affect drastically the growth

and yield of various crop plants including the legumes

[4]. However, improvements of legume crops by inocu-

lation of rhizobia or AMF alone or in combination have

been reported by several authors [18-23] under salt stress

conditions. In this study, the best salt tolerant streptomy-

cin resistant strain of Bradyrhizobium CAN-11 (specific

for V. radiata L.) and Glomus mosseae BAS-1 were util-

ized for cultivation of V. radiata in pot culture and under

field conditions.

The experimental data (Table 1 and Figures 1-3) re-

vealed that combined inoculation of Bradyrhizobium

CAN-11 and G. mosseae BAS-I increased the yield of

V.radiata cv. B-I followed by single inoculation of Bra-

dyrhizobium CAN-11 and G. mosseae BAS-I than the

control uninoculated set. All the growth characteristics

of V. radiata cv B-I were also improved simultaneously.

Moreover, in V. radiata cv B-I the relative growth rate of

total plant, shoot and root was also best in combined

inoculation than the single inoculation. [24] reported that

Rhizobium and Glomus sp. significantly increased the

shoot and root fresh and dry weight, number of nodules

in faba bean under saline condition. [25] reported that

alleviation of salt stress in Lactuca sativa could be

achieved by inoculation with Glomus sp. Similar benefi-

cial effects of dual inoculation of Rhizobium/Bradyr-

hizobium and AMF were reported on the growth charac-

teristics and yield of Medicago sativa [26], tomato [27],

soybean [28], maize [29], cotton [22] and Lotus glaber

[20].

Field experiments conducted in the saline soils of

Basanti, Canning and Kakdwip of South 24-Parganas;

Deuli, Kharampur and saimalpur of North 24-Parganas

and Kanthi and Tamluk of East Medinipur districts using

single and dual inoculation of Bradyrhizobium CAN-11

and G. mosseae BAS-I to V. radiata cv. B-I (Tables 2-4).

It was revealed that the crop grew well and produced

yields appreciably. The growth parameters like height of

the plants shoot and root-fresh and dry weights, number

of seeds per pods were increased under normal condi-

N. Singh et al. / Agricultural Sciences 2 (2011) 413-423

422

tions. Similar observations have been reported in soy-

bean [30], Sesbania aegyptiaca and S. grandiflora [21],

Vigna radiata [31] and on Pisum sativum [32].

The beneficial effects of dual inoculation on the

growth of V. radiata L. might be due to reduction in Na

uptake and increased uptake of P, N and Mg and high

content of chlorophyll in the inoculated plants which

have played important roles in salinity alleviating me-

chanism of plants [21].

Further it was revealed that when the pulse cultivation

was introduced in villages, namely Gabbani and Barbari

of South 24-Parganas as a second crop utilizing salt tol-

erant Bradyrhizobium CAN-11 and G. mosseae BAS-I as

the dual inoculation practices, the socio-economic con-

ditions of the household farmers changed dramatically

(Table 5). Similar beneficial report was reported by [33]

have corroborated our findings with V. radiata and could

find application in saline areas of West Bengal, India.

5. ACKNOWLEDGEMENTS

Authors are thankful to Prof. P. Bhattacherjee, Officer-in-Charge,

Nodule Research Laboratory, Bidhan Chandra Krishi Viswavidyalaya,

Mohanpur, Nadia, West Bengal, India for providing necessary facili-

ties.

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