internship report presented for the award of degree in soil microbiology at institute of soil and environmental science, University of agriculture, Faisalabad, Pakistan

2. Effect Of Rhizobium Species on
Growth Of Maize By Auxin
Biosynthesis
By
HASSAN SATTAR
2011-ag-3250

3. Introduction
 Legumes are very well known for their symbiotic
relationships with Rhizobium
 Rhizobium due to its great colonizing ability may be used
in non-legumes for improving crop growth
 One of its many positive effects on plant growth is auxin
biosynthesis.
 Several microorganisms including rhizobia have been
reported to synthesize auxins. Asghar et al., 2004; Zahir
et al., 2005).
 Auxin significantly improve vegetative growth of maize
crop

4. • Zahir et al . (2010) reported that Rhizobium inoculation
resulted in significant increase in various physical
parameters upto 17-80%, compared to control
Keeping in view these facts, pot study was conducted to
assess the effect of six isolates of rhizobia for their ability
to promote growth
and yield of maize

5. Materials And Methods
 Rhizobium species isolated from chickpea and
mungbean cultured on yeast extract mannitol
agar medium (YMA) were obtained from Soil
Bacteriology Section, Agri. Biotech.
Research Institute, AARI Faisalabad

6. Pot Experiment
 Pot study was conducted in summer using 5 Kg
soil capacity earthen pots filled with loamy soil mixed
with sufficient organic matter at Soil Bacteriology
Section, AARI, Faisalabad.
 The experiment was laid out in completely
randomized design(CRD) with three replications.
 Maize seeds were soaked in respective cultures
For 1 hour.
 The treatments were viz.
T1:cp1,T2:cp2,T3:cp3,T4:mb1,T5:mb2,T6:mb3,T7:
control

7.  Four seeds per pot was sown .
 The pots were arranged randomly at ambient light
and temperature and each treatment was
replicated thrice
 Daily irrigation ensured to meet the water
requirement in hot and dry weather
 No commercial fertilizer was applied.

8.  After 15 days of sowing , rhizosphere soil was taken
from two replicates to asses the auxin biosynthesis
by rhizobia.
 GPM broth prepared, autoclaved in test tubes filled
up to 10 mL and then 1 gram soil added aseptically
in laminar air flow cabinets.

9.  Test tubes were kept in incubator 28-30 °C for 1
week with daily shaking
 While measuring IAA-equivalents, 3.0 mL of filtrate
was taken in test tubes and 2.0 mL of Salkowski
reagent (2mL of 0.5M FeCl3 + 98mL of 35 %HClO4)was
added to it.
 The contents in the test tubes were allowed to stand
for half an hour for colour development. Similarly,
colour was also developed in standard solutions of
IAA.

10.  The intensity of colour was measured at 535nm by
using spectrophotometer as described by Sarwar
et al. (1992).
 Standard curve was used for comparison to
calculate auxins production by rhizobacteria.

11. Results
 Results revealed that bacterial inoculation
enhanced the maize growth significantly
 Results also prove that IAA produced in
rhizosphere by rhizobia affect growth
 Presence of auxin in rhizosphere soil confirms
it as a growth enhancer of maize plants
 The best response was from mungbean 1 and
mungbean 2

12. Rhizobium species affected the maize
growth and development significantly and
variable response was observed with the
isolates
Some isolates also show non significant or
even negative response , this is due to the
unability of rhizobia to colonize or some other
environmental conditions.

13. Host legumes isolates
IAA equivalents
(μg mL-1)
Chickpea
CP1 4.77
CP2 4.41
CP3 4.02
Mungbean
MB1 3.72
MB2 4.62
MB3 3.87
Control 3.68
Table 2. Influence of treatments on auxin production

14. Treatments
Root Length
(cm)
Shoot Length
(cm)
Fresh weight
(g)
Dry weight
(g)
CP1 20.33 31 2.94 0.6
CP2 21 32 3.18 0.65
CP3 24 33.34 3.1 0.86
MB1 20.66 33.83 2.97 0.55
MB2 21 32.66 2.53 0.45
MB3 20 29.34 2.89 0.48
Control 19.34 28.84 2.55 0.45
Table 1: Effect of inoculation with different isolates of rhizobia
on plant height, fresh biomass, straw yield and root length at
the time of harvest of maize plants grown in pots

15. 0
5
10
15
20
25
30
35
40
CP1 CP2 CP3 MB1 MB2 MB3 Control
Effect of chickpea and mungbean rhizobia on growth
parameters of maize
Root Length (cm) Shoot Length (cm)

16. 0
0.5
1
1.5
2
2.5
3
3.5
CP1 CP2 CP3 MB1 MB2 MB3 Control
Effect of chickpea and mungbean rhizobia on growth
parameters of maize
Fresh weight (g) Dry weight (g)

17. References
Asghar, H. N., Z. A. Zahir, M. Arshad and A. Khaliq
(2002). Relationship between in vitro production
of auxins by rhizobacteria and their growthpromoting
activities in Brassica juncea L. Biol.
Fertil. Soils, 35, 231-237.
Khalid, M., M. Arshad and Z.A. Zahir. 2006.
Phytohormones: Microbial production and application.
p. 207-220. In: Biological Approaches to Sustainable
Soil Systems. N. Uphoff, A.S. Ball, C. Palm, E.
Fernandes, J. Pretty, H. Herren, P. Sanchez, O. Husson,
N. Sanginga, M. Laing and J. Thies (eds.) CRC Press,
Taylor & Francis, Boca Raton, New York, USA
.

18. Khalid, A., M. Arshad and Z.A. Zahir (2004).
Screening
plant growth promoting rhizobacteria for
improving growth and yield of wheat. J. Appl.
Microbiol., 96: 473-480.