Determining gamma radiation dose......Leonard

DETERMINING GAMMA RADIATION
DOSE FOR INDUCED MUTATION IN
MAIZE(ZEA MAYS)
By Chilembo Leonard
Comp: 11004517
SUPERVISORS : DR. K. MUNYINDA
DR. L. TEMBO

INTRODUCTION
Maize (Zea mays L.) Maize is the most
significant cereal crop and staple food for more
than 1.2 billion people in Sub-Saharan Africa
(SSA) and Latin America (Vivek et al., 2005)
However, maize yield is low due to biotic and
abiotic stresses on the crop
Creation of genetic variation through induced
mutation from which desired mutants can be
selected proves to provide great success in
plant breeding programmes (Ahloowalia,
2004).

STATEMENT OF THE PROBLEM
Low maize yield is an increasing challenge in
ensuring food security. This calls for breeding
methods such as induced mutation to generate
maize genotypes with desired traits such as
drought, low soil fertility, disease and pest
resistance (Parr et al., 2005).

JUSTIFICATION OF THE STUDY
Induced mutation is a significant tool for
creating genetic variations among the maize
genotypes (Wani and Anis, 2008).
Variations enables the selection of desired
traits such as drought and low fertility
tolerance to solve the problem of low maize
yields (Ashraf, 2009).

OBJECTIVE
To determine the optimum gamma radiation
dose for induced mutation in maize for
producing desirable traits.

RESEARCH HYPOTHESIS
 Gamma irradiation produces mutation
derived maize lines with desirable traits
(drought, high nutrient use efficiencies)

MATERIALS AND METHODS
The materials used in the study were five
genotypes:
GV 635,
ZARICZH 122,
ZARICZH 1021,
ZARICZH 131002 and
ZARICZH 131008
Got from Zambia Agricultural Research Institute
(ZARI) provided by the department of plant
science.

MATERIALS AND METHODS CONT’D
The genotypes were irradiated at four
different doses (0, 150, 300, 450 and 600 Gy)
Irradiated seeds were then planted in pots in
the greenhouse

MATERIALS AND METHODS CONT’D
Planting was done on 23rd January 2016 and
The experiment was carried out for a period of
30 days.

Parameters measured
Plant germination was recorded 7 days after
planting
Plant height,
Leaf length,
leaf width and
chlorophyll content were all measured 30
days after planting
Leaf area (L × W × A ); A=0.75 (Pearce, 1975)

EXPERIMENTAL DESIGN
• Complete Randomized Design (CRD)
• Two factors:
– Gamma radiation dose (Gy)
– maize genotypes
• 5 treatments which are gamma radiation
doses (0, 150, 300, 450 and 600 Gy).
• 4 replications of radiation dose.
• Data analyzed by GenSat18

Genotypic Mean Squares for measured
Parameters evaluated across Gamma ray
doses (Gy)
Source of D.f Germ Plant height Leaf length leaf Area Chlorophyll
Variation MS MS MS MS MS
Genotype 4 7.534 ** 370.163 *** 144.940*** 669.3*** 59.91ns
Dose 4 9.403** 221.828 *** 180.174*** 1246.0*** 37.14ns
Genotype×Dose 16 8.851*** 139.4ns 0.11 29ns 28.638ns 42.19ns
Residual 70 2.208 3.231 6.730 106.3 25.51
CV% 16.5 4.5 4.2 16.3 15.6
KEY
*,**,***, Significant at P=0.1, P=0.05 & P=0.001 respectively , ns=Non significant, MS=Mean
Square, DF=Degree of Freedom.

Fig 1: Effects of gamma radiation dose
on plant height
0
10
20
30
40
50
60 0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH 131002 ZARICZH 131008
Plantgrowth(cm)
GENOTYPE AND RADIATION DOSE

Fig 2: % Reduction in plant height
0
5
10
15
20
25
30
150 Gy 300 Gy 450 Gy 600 Gy
Plantheight(cm)
Gamma radiation dose
% Reduction

on leaf length
0
5
10
15
20
25
30
35
40
45
50
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH
131002
ZARICZH
131008
Leaflength(cm

Fig 4: % Reduction in leaf length
0
5
10
15
20
25
30
35
150 Gy 300 Gy 450 Gy 600 Gy
Leaflength(cm)
% Reduction

on leaf area
0
10
20
30
40
50
60
70
80
90
100
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
0
150
300
450
600
GV 635 ZARICZH 1021 ZARICZH 122 ZARICZH 131002 ZARICZH 131008
leafarea(cm²)

Fig 6: % Reduction in leaf area
0
10
20
30
40
50
60
150 Gy 300 Gy 450 Gy 600 Gy
Averageleafarea(cm²)
% Reduction

DISCUSSION
At 0 Gy all the genotypes showed normal growth
but had some stimulating growth at 150 Gy
This is because the stimulatory effect is attributed
to the production of growth hormone, kinetin,
which forms hormonal balance
Hormonal balance is formed due to increasing
number of cells to overcome stress factors such as
frequency of chromosomal damage with increasing
fluctuations of light intensity and temperature
because of gamma radiation (Chung and J.S. Kim,
2007).

CONCLUSION
The optimum gamma radiation dose found for
irradiating maize genotypes was 450 Gy
This is because radiation dose of 450 Gy
caused a percentage reduction growth in the
parameters measured of more than 20%
A dose causing percentage reduction of 20
and above is considered optimum, where
maximum mutation is produced with minimal
damage to the plant (Kangarasu S, 2014).

RECOMENDATION
Since the optimal gamma irradiation dose was
determined, growing maize plants irradiated
at 450 Gy to maturity to observe yield and
other characteristics should be done.

References
• Ahloowalia (2004). Global impact of mutation-derived varieties. Euphytica 135:187-204.
• Ashraf M (2009). Changes in antioxidant enzymes and some key metabolites in some genetically
diverse cultivars of radish (Raphanus sativus L.). Environ. Exp. Bot., 67: 395-402
• Chung and J.S. Kim, 2007. Effects of markers. African Journal of Biotechnology, gamma irradiation on
morphological changes and 8(19): 4824-4829. biological responses in plants. Micron, 38: 553-564
• Kangarasu S (2014). Determination of Lethal Dose for Gamma Rays and Ethyl Methane Sulphonate
Induced Mutagenesis In Cassava (Manihot Esculenta Crantz). Department of Plant Genetic Resources,
Centre for Plant Breeding and Genetics, Tamil Nadua Agricultural University, Coimbatore.
• Parry et al., (2007). Prospects for increasing photosynthesis by overcoming the limitations of Rubisco.
Journal of Agricultural Science 145, 31–43.
• Pearce et al., (1975). Maize plant physiology. Iowa State University Press, Ames, IA. USA
• Vivek et al., (2005). Characterization of maize germplasm grown in eastern and southern Africa:
Results of the 2004 regional trials coordinated by CIMMYT. Harare, Zimbabwe. CIMMYT. 68pp.

Determining gamma radiation dose......Leonard

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