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In ternationa l
Scholars
Journa ls

  

African Journal of Agricultural Marketing ISSN: 2375-1061 Vol. 12 (5), pp. 001-006, May, 2024. Available online 
at www.internationalscholarsjournals.org © International Scholars Journals 

 

Author(s) retain the copyright of this article. 
 
 

Full Length Research Paper 

  

Graphical Analysis of Genetic Control of Diverse 
Traits in Maize Inbred Lines 

 
Zahra khodarahmpour 

 
Islamic Azad University, Shoushtar Branch, Shoushtar, Iran. E-mail: Zahra_khodarahm@yahoo.com. 

 
Accepted 12 January, 2024 

 
This study was carried out in order to investigate the genetic structure of the twenty-eight maize hybrids established 
from eight maize inbred lines. The seed of the F1 population along with their parents were planted in Iran in 2008, 
using RCBD with three replications. Estimation of gene effects and some of the genetic parameters and graphic plot 
drawing of Hayman-Jinks method were accomplished. Statistics a and b for all traits was significant. Considering the 
average degree of dominance, as well as the Hayman graphical plot, dominance effects were observed for grain yield 
and plant growth period traits over dominance, complete dominance for grain diameter and additive gene action with 
partial dominance for ASI, grain filling period, grain number in row, grain number in ear, grain row number in ear, ear 
diameter, grain depth, 1000 grain weight and hektolitr weight traits. 

 

Key words: Maize, genetic parameters, graphic plot. 

 
INTRODUCTION 

 
Maize (Zea mays L.) is one of the important cereal crops 
of Iran and the world after wheat and rice. Recent 
projections by the International Food Policy Research 
Institute indicate that by 2020, the demand for maize in 
developing countries will overtake that for wheat and rice 
(Gerpacio and Pingali, 2007). In Iran, the average grain 

yield ha
-1

 in 2007 was 7.6 t ha
-1

, whereas the soil and 
climatic conditions of Iran are suitable for maize 
production, but the yield is low when compared to the 

United States of America with 9.5 t ha
-1

 in 2007. Thus, it 
is prerequisite to select promising hybrids for different 
conditions in order to speed up economical crop 
production.  

Maize breeders have successfully exploited heterosis 
for grain yield by crossing inbred lines to develop 
desirable hybrids. However, the nature of gene action 
involved in expression of heterosis for the grain yield and 
other traits of elite maize hybrids remains unresolved.  

The choice of efficient breeding program depends on a 
large knowledge of the type of gene action involved in the 
expression of the character. Dominance gene action 
would favor the production of hybrids, whereas additive 
gene action indicates that standard selection procedures 
would be effective in breeding about changing the 
character (Edwards et al., 1976).  

Betran et al. (2003) reported that the gene action for 
yield, ear diameter, number of grain in row, grain depth 
and 1000 grain weight, is over dominance, while the gene 

 
 
 

 
action for number of grain rows is partial dominance. 
Barati et al. (2003) showed that gene action for yield, 
number of grain in row and 1000 grain weight is over 
dominance, but for number of grain rows, it is partial 
dominance. Also, Srdic et al. (2007) found that dominant 
gene effects were more significant in maize grain yield 
and number of grains per row, while additive gene effects 
were more important for grain row number and 1000 
grain weight. The mode of inheritance of grain row 
number was partial dominance, while over dominance 
was of greater importance for grain yield, number of 
grains per row and 1000 grain weight. Wattoo et al. 
(2009) revealed that the yield potential like number of 
days taken for tasselling and number of days taken for 
silking, plant height, number of ears per plant, number of 
grain rows per ear, number of grains per row, 100 grain 
weight and grain yield per plant were controlled by the 
over dominance type of gene action.  

Irshad-Ul-Haq et al. (2010) revealed that non-additive 
genetic effects were more pronounced in the inheritance 
of plant height, days to 50% tasseling, days to 50% 
silking, ear height and grain yield per plant. The graphic 
analysis showed that all the characters were under the 
genetic control of the over dominance type of gene 
action. Also, for grain yield, the parents (NYP-8 and 
NCQPM-2) were close to the point of origin and had an 
excess of dominant genes, whereas FR-37 being farthest 
from the origin was carrying a maximum number of 



2 

 

 
 
 

 
Table 1. Analysis of variance mean squares obtained from 8×8 diallel crosses and analysis of the mean squares of diallel crosses of eight maize inbred lines.  
 

 
Source df 

 Grain Grain Plant Grain Grain Ear Grain Grain 1000 Hektolitr 
Grain yield Grain yield  

 
ASI(day) filling filling growth number row diameter diameter depth grain weight  

 of  
(kg/hac) (kg/hac)  

   

period period period in ear number (cm) (cm) (cm) weight (gr/lit)  

 variance     
 

   

(day) (day) (day) 
 

in ear 
   

(gr) 
   

 

           
 

                 

 Block 2 5.08ns 53.19* 53.19* 8.58** 244832** 14* 3.88** 0.003ns 0.17ns 4946ns 5998ns 2317944* 2317944* 
 

 Genotype 35 4.16* 68.5** 68.5** 6.18** 135981** 9.57** 1.74** 0.05** 0.35** 10738** 5170* 1316319** 1316319** 
 

 Error 70 2.31 13.86 13.86 1.53 120742 6 0.49 0.02 0.18 3669 2608 584733 584733 
 

 a 7 7.87** 222.5** 222.5** 327.9** 76050.9* 6.53** 0.78** 0.03** 0.09** 46883** 11128** 1944439** 1944439** 
 

 b 28 7.71** 103.64** 103.64** 93.16** 59029.1** 6.11** 0.66** 0.02** 0.07** 13836.8** 5208.6** 2775917** 2775917** 
 

 b1 1 4.88ns 370.9** 370.9** 23.05ns 305419** 5.84* 0ns 0.02* 0.04ns 10108.7ns 49859.8** 10723930** 10723930** 
 

 b2 7 7.32** 123.78** 123.78** 116.4** 26550.7ns 13.75** 0.7** 0.01* 0.04ns 13110** 2430.6* 2488819** 2488819** 
 

 b3 20 8** 83.23** 83.23** 88.5** 77580** 3.45** 0.67** 0.02** 0.08** 14277.6** 3209.8** 2479001** 2479001** 
 

 Error 126 2.1 12.19 12.19 9.43 27638.8 1.20 0.11 0 0.02 3320 983 535380 535380 
 

 
ns, * and **: nonsignificant, significant at 5 and 1% probability level, respectively. 
 

 

recessive alleles.  
Hussain et al. (2009) reported that plant height, 

leaf area, grain yield per plant and harvest index, 
under normal and water stress conditions, 
indicated additive gene action with partial 
dominance. Also, over dominance type of gene 
action was recorded for grains per row and 100 
grain weight. Heritability estimates ranged from 
moderate to high (54 to 85%) for various traits.  

Rezaei et al. (2005) reported that high 
broadsence heritability estimates (0.85 to 0.95) 
were observed; but for most traits, the estimates 
for narrowsence heritability were relatively low, 
while the lowest values belonged to number of 
grain row and grain yield (0.23 and 0.38), 
respectively.  

Heritability degrees varied from low to moderate 
for grain yield (Singh et al., 2002; Kalla et al., 
2001).  

The diallel analysis study of the genetic traits 
would certainly be a valuable aid in the selection 
and breeding for better maize hybrids and 

 
 

 

synthetics. The information derived may be helpful 
in developing the selection criterion and selection 
of most promising inbred lines for further future 
breeding programs. 

 

MATERIALS AND METHODS 

 
The study was conducted at Shushtar City located in 
Khuzestan province, Iran (32°2 N and 48°50′ E, 150 m asl) 
in the year 2008. The type of soil found at this location is 
clay loam, and its pH = 7.6 with EC = 0.5 mmhos/cm.  

The experimental material comprised eight inbred lines of 
maize (A679, K3651/1, K3640/5, K47/2-2-1-21-2-1-1-1, K19, 
K18, K166A and K166B). The lines were crossed during 
spring, in 2008 in a partial diallel fashion to obtain grains of 

direct crosses. The F1 seed along with their parental inbred 

lines were sown in a triplicated randomized complete block 
design in 27 July (which was the planting date). Each plot 
contained 3 rows that are 75 cm apart and 9 m in length and 
they consisted of 45 hills, two seeds of which were sown and 
one seedling of which was removed at the 4 leaves stage. The 
experiment was irrigated every 5 days, while fertilizers were 

applied prior to sowing at a rate of 120 kg N ha
-1

 and 140 kg P 

ha
-1

, and an additional side 

 
 

 

dressing of 120 kg N ha
-1

 was applied at the six leaves 

stage of maize plants. Data pertaining to anthesis silking 
interval (ASI), grain filling period, plant growth period, grain 
row number in ear, grain number in row, grain number in 
ear, ear diameter, grain diameter, grain depth, 1000 grain 
weight, hektolitr weight and grain yield traits were analyzed 
using SPSS software. Genetic analysis was done 
according to the diallel technique as described by Hayman 
(1954) and Jinks (1954). The information on gene action 
and presence of dominant and recessive genes in the 
parents was also inferred by plotting the covariance (Wr) of 
each array against its variance (Vr). 
 

 

RESULTS AND DISCUSSION 

 
The analysis of variance (Table 1) showed that 
mean square due to inbred lines and hybrids for 
all traits was significant, indicating the existence of 
variability among genotypes for all traits and thus 
the use of Hayman-Jinks model was allowed for 
genetic analysis of these characters.  

The results of the analysis of variance of F1 data 
showed significant differences for a and b, 



3 

 

 
 
 

 
Table 2. Estimation of the statistical indices and genetics parameters for different traits in eight maize inbred lines of diallel crosses.  

 
  

Grain filling 
Plant Grain row Grain Grain Ear Grain Grain 

1000 grain 
Hektolitr Grain 

 

Trait ASI (day) growth number number number diameter diameter depth weight yield  

period (day) weight (gr)  

  
period (day) in ear in row in ear (cm) (cm) (cm) (gr/lit) (kg/hac)  

    
 

D 1.25
ns

 114.5* 39.7** 7.4** 133.4ns -22034ns 0.58** 0.01ns 0.05ns 9876.99* 4274.35* 275424
ns

 
 

H1 1.2** 88.8** 82.5** 6.42** 120.1* 20654.8** 0.52** 0.01* 0.04* 9458.5** 3162.03* 1982055** 
 

H
2
 1** 61.07** 55.9** 3.29** 127.6* 21214.8** 0.37** 0.01* 0.03** 7045.6** 2830.8* 1499272** 

 

F 2.11
ns

 24.88* 39.9** 6.1** -32.5ns -6340.4
ns

 0.27** 0.003
ns

 0.02* 3694.2* 653.02ns 646364
ns

 
 

h
2
 0.42

ns
 52.4** 2.07

ns
 0.689

ns
 231.08ns 40761.6** -0.01** 0.003

ns
 0.002

ns
 1020.25

ns
 7991.36** 1490713

ns
 

 

E 0.7** 4.08** 3.15** 0.396** 35.8** 9212.9** 0.04** 0.001** 0.008
ns

 1106.7** 327.6** 178460** 
   

H 1 
0.98 0.88 1.44 0.93 0.95 0.97 0.95 1 0.89 0.98 0.86 2.68 

 

 
 

D 
 

            
  

 H 2 
0.21 0.17 0.17 0.13 0.27 0.26 0.18 0.25 0.19 0.19 0.22 0.19 

 

  
 

 

4 H 1 
 

             
 

 h
2
b 0.63 0.86 0.90 0.72 0.56 0.44 0.77 0.70 0.58 0.76 0.78 0.71 

 

h
2
n 0.12 0.31 0.44 0.15 0.17 0.11 0.18 0.23 0.15 0.39 0.32 0.09 

 

 
ns, * and **: nonsignificant, significant at 5 and 1% probability level, respectively. 

 

 

suggesting the presence of both additive and 
dominance genetic effects in the expression of all 
traits (Table 1). The significant b1 item revealed 
the presence of directional dominant effects of 
genes. However, the b1 item for grain filling 
period, grain number in ear, grain row number in 
ear, grain number in row, hektolitr weight, grain 
diameter and grain yield traits was significant. 
Among inbred lines, asymmetrical gene 
distribution for ASI, grain filling period, plant 
growth period, grain row number, 1000 grain 
weight, hektolitr weight, ear diameter, grain 
diameter and grain yield were evident due to the 
significance of the b2 item. Also, among parents, 
specific gene effects for all traits were evident due 
to the significance of the b3 item. Irshad-Ul-Haq et 
al. (2010) reported that a, b, b1, b2 and b3 items 
for all traits were significant. 

 
 

 

In Table 2, the genetic component of variation 
and the significant value of D for grain filling 
period, plant growth period, grain row number in 
ear, ear diameter, 1000 grain weight and hektolitr 
weight indicated the importance of additive 

genetic effects. Significant H components (H1 and 

H2) revealed the importantce of dominant 
variation, while different distribution of dominant 

genes was displayed by an unequal value of H1 

and H2. 
The additive and dominance effects covariance  

(F) used as a criterion of dominance and additive 
allele frequency for grain filling period, grain row 
number in ear, 1000 grain weight, ear diameter 
and grain depth, resulted to a significant and 
positive value which indicated that the positive 
genes were more frequent.  

The  important  effect  of  heterozygous  loci  for 

 
 

 

plants, which was indicated by a significant value 

of h
2
 for grain filling period, plant growth period, 

grain number in ear, hektolitr weight and ear 
diameter traits was significant.  

The environmental variation (E) was significant 
for all traits, except for grain depth trait, indicating 
important environmental effects on traits. Degree  

of  dominance 
H 1 

indicated  over  dominance 
 

 
 

D 
 

  
  

gene action for grain yield and plant growth 
period, but for grain diameter, it showed complete 
dominance, while for other traits, it showed partial 
dominance gene action. Betran et al. (2003) 
reported that the gene action for yield, ear 
diameter, number of grain in row, grain depth and 
1000 grain weight traits is over dominance, but for 
number of grain rows, it is partial dominance. 



4 

 

  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Figure 1. Vr/Wr graph of (A) ASI (day), (B) grain filling period (day), (C) plant growth period (day),  
(D) grain row number in ear, (E) grain number in row, (F) grain number in ear, (G) ear diameter (cm),  
(H) grain depth (cm), (I) grain diameter (cm), (J) 1000 grain weight (gr), (K) hektolitr weight (gr/L) 
and (L) grain yield (kg/plot). 1: K18; 2: K3651/1; 3: A679; 4: K166A; 5: K166B; 6; K3640/5; 7: K47/2-
2-1-21-2-1-1-1 and 8: K19. 



5 

 

 
 
 

 

Hussain et al. (2009) reported that plant height, leaf area, 
grain yield, per plant and harvest index, under normal and 
water stress conditions, indicated additive gene action 
with partial dominance. Shiri et al. (2010) reported that 
the type of gene action for grain yield was additive and 
non additive. Also, over dominance type of gene action 
was recorded for grains per row and 100 grain weight. 
However, over dominance type of gene action in maize 
was reported by Prakash et al. (2004) and Ali et al. 
(2007) for grain yield and for all traits by Wattoo et al.  
(2009) and Irshad-Ul-Haq et al. (2010). 

The  proportion  of  genes  for  traits  with  positive  and 

negative effects 
H 2 

in the parents was found to be 
 

 
 

4 H 1 
 

  
  

higher than 0.25 for grain number in row and grain 
number in ear, while for grain diameter, it was 0.25 and 
for other traits, it was less than 0.25, denoting asymmetry 
at the loci showing dominance.  

Broad sense heritability varied from 0.44 for grain 
number in ear to 0.90 for plant growth period, while 
narrow sense heritability was of non-additive nature and 
displayed a lower percentage than 44% of the genetic 
variation transferred from the parents. Heritability degrees 
were reported from low to moderate for grain yield (Singh 
et al., 2002; Kalla et al., 2001). Rezaei et al. (2005) 
reported high broadsence heritability estimates (0.85 to 
0.95) for most traits, while the estimates for narrowsence 
heritability were relatively low, with the lowest values 
belonging to number of grain row and grain yield (0.23 
and 0.38), respectively. However, Hussain et al. (2009) 
reported that heritability estimates ranged from moderate 
to high (54 to 85%) for various traits.  

Graphical representation revealed that the regression 
line intercepted the Wr axis just below the point of origin 
which indicated the presence of over dominance type of 
gene action for plant growth period (Figure 1C) and grain 
yield (Figure 1L) traits and complete dominance for grain 
diameter (Figure 1F), while for ASI, grain filling period, 
grain number in row, grain number in ear, grain row 
number in ear, ear diameter, grain depth, 1000 grain 
weight and hektolitr weight (Figures 1A, B, D, E, G, H, I, J 
and K) traits, the regression line intercepted the Wr axis 
just above the point of origin which indicated the 
presence of partial dominance (additive) type of gene 
action. Nonetheless, these results were in agreement 
with the results received for the degree of dominance  

H 1 
D

 . 
 

Inbred line A679 for ASI trait (Figure 1A), being closer 
to the origin, possessed maximum dominant genes, while 
inbred line K3640/5 had mostly, recessive alleles. 
However, lines K3640/5 and A679 for grain filling period 
(Figure 1B), lines K19 and K166B for plant growth period 
(Figure 1C), lines K3651/1 and K47/2-2-1-21-2-1-1-1 for 
grain row number in ear (Figure 1D) trait, inbred lines 
A679 and K166A for grain number in row (Figure 1E) 
trait, inbred lines K3640/5 and K3651/1 fo r grain number 

 
 
 
 

 

in ear (Figure 1F) trait, lines K166B and K3640/5 for ear 
diameter (Figure 1G), lines K166B and K3640/5 for grain 
depth (Figure 1H), K18 and K166A for 1000 grain weight 
(Figure 1J), lines K166A and K166B for hektolitr weight 
trait (Figure 1K) and lines K166B and K18 for grain yield 
(Figure 1L) had respectively, maximum dominant and 
recessive genes. For grain diameter (Figure 1I) trait, lines 
K3651/1, K166A and K3640/5 had maximum dominant 
genes, while line K18 had maximum recessive genes. 
Saleem et al. (2007) indicated that inbred lines B-46 and 
line EX-285 possessed maximum dominant genes for 
100 grain weight and grain yield per plant, respectively. 
For number of days taken to tasseling, number of days 
taken to silking and number of grain row per ear, inbred 
line SYP-24 had maximum dominant genes. Irshad-Ul-
Haq et al. (2010) indicated that for grain yield, the parents 
(NYP-8 and NCQPM-2) were close to the point of origin 
and had an excess of dominant genes, whereas FR-37 
being farthest from the origin was carrying a maximum 
number of recessive alleles.  

In this study, all traits except grain yield, plant growth 
period and grain diameter were controlled by additive 
type of gene action. Prediction in the case of additive 
gene action would be expected to be more reliable as 
compared to the characters which are controlled by the 
non-additive type of gene action. A preponderance of 
non-additive effects would not favor mass selection in 
altering any traits, but pedigree test, sib test, progeny test 
or various combinations among them, will certainly be 
required to improve grain yield. However, inheritance of 
grain yield and plant growth period appeared in the over 
dominance type of gene action. Conclusively, grain yield 
and plant growth period are non-additively controlled and 
selection for these population must be practiced with 
great care to develop pure breeding line. 
 

 
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