combining ability of popcorn lines for seed quality and agronomic traits
TRANSCRIPT
Combining ability of popcorn lines for seed qualityand agronomic traits
Lia Mara Moterle • Alessandro de Lucca e Braccini • Carlos Alberto Scapim •
Ronald Jose Barth Pinto • Leandro Simoes Azeredo Goncalves •
Rosana Rodrigues • Antonio Teixeira do Amaral Junior
Received: 17 August 2010 / Accepted: 10 May 2011 / Published online: 22 May 2011
� Springer Science+Business Media B.V. 2011
Abstract Popcorn breeding programs in Brazil have
emerged but despite some advances there is still a lack
of material performance studies specially regard to
seed quality, in different agricultural seasons. This
research was carried out to estimate the popcorn
combining ability from biparental crosses between
eight tropical and one temperate lines in two agricul-
tural seasons (2008 and 2009) with regard to eight
traits related to seed quality, in addition to three
agronomic traits related to popping expansion.
Method 4, proposed by Griffing (Model 1), was used
to verifying the importance of the dominance effect in
the genetic control of the seed quality traits, favouring
the identification of superior hybrids through seed
tests in the laboratory with low cost. The lines from
Zelia and CMS42 were promising in obtaining
hybrids with superior seed quality and greater popping
expansion. The hybrids Zelia 9 IAC-112, CMS42 9
UEM M2-1, CMS43-1 9 IAC-112 and UEM M2-
2 9 Zaeli expressed superior SCA for grain yield,
popping expansion and at least two seed quality traits.
These hybrids are materials of interest for cultivation
in different planting seasons.
Keywords Zea mays L. � Diallel �Seed quality tests � Grain yield
Introduction
In Brazil, popcorn consumption has been increasing
over the years and because of that growing popcorn is
a very economic attractive activity to farmers all over
the country (Freitas Junior et al. 2009; Mendes de
Paula et al. 2010). Estimative from governmental
sectors pointed that the price obtained for one
popcorn grain package (60 kg) is about three times
the price paid for common corn grain (Agrianual
2010). However, several studies of the Ministry of
Agriculture have stated that the production is still
limited compared to the market potential of the crop
(Arnhold et al. 2009). The main restriction for the
crop is the lack cultivars options adapted to Brazilian
conditions, with favourable agronomic traits and a
high rate of popping expansion (Scapim et al. 2010).
The development of popcorn breeding programs
which aim obtaining improved populations and, or
hybrids adapted to Brazilian conditions are dramat-
ically important to diminish the dependence of
L. M. Moterle � A. de Lucca e Braccini �C. A. Scapim � R. J. B. Pinto
Department of Agronomy, Universidade Estadual de
Maringa (UEM), Avenida Colombo 5790, Maringa,
PR 87020-900, Brazil
L. S. A. Goncalves � R. Rodrigues �A. T. do Amaral Junior (&)
Plant Breeding Department, Universidade Estadual do
Norte Fluminense Darcy Ribeiro (UENF), Campos dos
Goytacazes, RJ 28013-602, Brazil
e-mail: [email protected]
123
Euphytica (2012) 185:337–347
DOI 10.1007/s10681-011-0458-2
foreign genotypes. Popcorn breeding programs in
Brazil have emerged with the use of intra and
interpopulational recurrent selection to increase pro-
ductivity and popping expansion (Daros et al. 2004;
Faria et al. 2008; Freitas Junior et al. 2009; Amaral
Junior et al. 2010); composite obtainment (Rangel
et al. 2008; Vieira et al. 2009a; Scapim et al. 2010);
evaluation and introduction of disease resistance in
commercial materials (Miranda et al. 2002; Vieira
et al. 2009b); evaluation of the genetic diversity for
agronomical traits and molecular markers (Dandolini
et al. 2008; Miranda et al. 2008; Munhoz et al. 2009;
Leal et al. 2010; Trindade et al. 2010); use of in vitro
culture (Ricci et al. 2007; Fernandes et al. 2008);
hybrids obtainment and its evaluation (Vieira et al.
2009c; Vieira et al. 2009a; Silva et al. 2010).
Despite these advances, comparing with common
corn, there is a lack of studies with regard to popcorn
seed quality, as well as studies of the inheritance of
these traits. Seed quality can be defined as the
summation of all genetic, physical, physiological and
sanitary attributes that affect its capacity to conduct
vital functions, characterised by its germination,
vigour and longevity (Goggi et al. 2008).
According to Delouche (1985), the use of traits
related to seed quality in breeding programs should
be more prominent, as they prevent seed deterioration
in the field and increase the longevity during storage,
as well as the germination capacity and emergence
under non-favourable conditions.
The maximum potential for seed quality is
controlled genetically, a complex character controlled
by many genes (Goggi et al. 2007). In this sense, the
diallel analysis can be used as one suitable tool for
supplying information on predominantly gene effects
on seed quality traits.
Gomes et al. (2000) evaluated the combining
ability of six common tropical corn and verified that
general combining ability (GCA), specific combining
ability (SCA) and reciprocal effects were significant
(P \ 0.01) and that the magnitude of the quadratic
components indicated the greater importance of the
dominance effects for the majority of the tests used
on the evaluation of seed quality.
On the other hand, Barla-Szabo et al. (1989)
studied the genetic control of seed vigour for six
common temperate corn and found evidence for an
additive effect in the genetic control. Antuna et al.
(2003) also verified that the additive effect was
predominant in seed quality expression of common
corn.
This study aimed to evaluate the combined ability
of nine inbred popcorn, eight from a tropical climate
and one from a temperate climate, for seed quality,
agronomical traits and popping expansion to evaluate
the potential of these lines and their hybrids to thrive
in two agricultural seasons.
Materials and methods
Genitors and hybrid attainment
Nine popcorn lines at the Breeding Popcorn Program
of the State University of Maringa were used
(Table 1). The crosses were carried out in a complete
diallel scheme, obtaining 36 F1 hybrids. To obtain
hybrids, seeds from the lines were cultivated at
0.90 m spacing between lines and 0.20 m between
plants in October of 2007. Kraft paper bags were used
to collect pollen grains during budding to accomplish
crossing between the lines.
Evaluation of the seed quality traits
Germination test (GER)
Performed with eight sub-samples of 50 seeds in
germination chamber and temperature of 25�C for
7 days, evaluating the percentage of normal
seedlings.
First count of germination test (IC)
Held in conjunction with the previous procedure,
using the same methodology, with assessment on the
fourth day after sowing.
Accelerated aging (ACC)
Led with 42 grams of seeds arranged on stainless
steel screen inside plastic boxes of ‘‘gerbox’’ type,
containing 40 mL of distilled water. Subsequently,
the boxes were transferred to a B.O.D.-type oven
with 42�C of temperature for 72 h. The evaluation
was carried out on the fourth day after sowing.
338 Euphytica (2012) 185:337–347
123
Modified cold test (COLD)
Performed with four subsamples of 50 seeds arranged
in rolls of germitest paper, surrounded by plastic bags
and sealed with adhesive tape. The rollers built in this
condition for 7 days in B.O.D-type oven, with the
temperature of 10�C. After this period the seeds were
transferred to a germination chamber with the
temperature of 25�C for 4 days. The evaluation was
carried out according to the criteria adopted for the
germination test.
Electrical conductivity (ECO)
It was conducted with four subsamples of 25 seeds.
Initially, the seeds were weighed in balance with an
accuracy of 0.001 g and placed in plastic cups with a
capacity for 200 ml. After weighing, were added
75 ml of deionized water in the plastic cups that
contained the seeds (‘‘bulk system’’). These were
then transferred to a B.O.D.-type oven with the
temperature of 25�C for 24 h. The reading of
electrical conductivity in the solution of imbibition
was performed using a benchtop microprocessor-
controlled digital bench, ACA model 150, Alpax
brand. The result was expressed in lS cm-1 g-1
seeds.
Seedlings emergence in sand seedbed (SE)
Conducted with four subsamples of 50 seeds in sand
packed in plastic trays. The test was performed in
greenhouse and moisture maintained with moderate
irrigation, once a day early in the morning. The
results were expressed as a percentage of seedling on
the fifteenth day after sowing. The speed of emer-
gence (ES) was conducted in conjunction with the
seedling emergence in sand seedbed. Counts of the
number of normal seedlings were held daily, resulting
in a cumulative value. This way, with the number of
normal seedlings for each reading, obtained at
greenhouse was calculated the speed of emergence
(ES) and the speed of emergence index (ESI)
employing the formulas proposed by Edmond and
Drapala (1958) and Maguire (1962), respectively.
The evaluation of seed quality was performed
using a completely randomized experimental design
with three replications for ACC, COLD, ECO, SE,
ES and ESI; and eight replications for IC and GER.
Evaluation of the agronomical traits
The assays were carried out in two cultivation
seasons, one sowed in September 2008 (normal
harvest, rainy season) and another in March 2009
(second crop, dry season), using 36 F1 hybrids
(Table 1). The experiments were performed using a
triple lattice design with 36 genotypes, in which the
experimental plot was formed by a 5.00 m length row
with 0.90 m spacing between lines and 0.20 m
between plants.
The agronomical traits evaluated were: i) plant
height (PH), in cm, obtained from the soil level at the
top of the three competitive plants in each plot; ii)
height of the first ear insertion (HFI), in cm,
expressed by the soil level measurement at the first
Table 1 Generation of self-pollination, genealogy, origin, grain colour and climate of the popcorn lines used
Strain Generation of
self-pollination
Parent Origin Grain colour Climate
Zelia S9 Tree-way hybrid Pioneer Orange Tropical
CMS 42-1 S9 Composite Embrapa Yellow Tropical
CMS 43-1 S9 Composite Embrapa White Tropical
CMS 43-2 S9 Composite Embrapa White Tropical
UEM-J1 S9 Variety UEM Orange Tropical
UEM M2-1 S9 Variety UEM Orange Tropical
UEM M2-2 S9 Variety UEM Orange Tropical
Zaeli S9 Tree-way hybrid UEM Orange Temperate
IAC-112 S6 Simple hybrid IAC Orange Tropical
Embrapa Empresa de Pesquisa Agropecuaria Brasileira (Brazilian Agricultural Research Corporation), UEM Universidade Estadual
de Maringa (Maringa State University) and IAC Instituto Agronomico de Campinas (Campinas Agronomic Institute)
Euphytica (2012) 185:337–347 339
123
ear insertion in the same three plants per plot; and iii)
grain yield (GY), expressed in kg ha-1, corrected for
13% humidity standard; and popping expansion (PE),
express in m Lg-1. Popping expansion was assessed
in a popcorn machine developed by Embrapa/Instru-
mentacao Agropecuaria, incorporating an electronic
resistor and thermostat. Two grain samples of 30 g
were obtained from each plot. After pre-heating the
machine to 270�C, each sample was cooked for
2.5 min. Expanded volume was measured in a
2,000 ml graded test tube. Popping expansion was
calculated as the ratio of expanded volume to 30 g
grain sample.
The agronomical traits evaluated in the field using
triple lattice design in two seasons (2008/09 and
2009) were processed through joint analyses.
Statistical analysis
The results obtained for seed quality and the agro-
nomical traits were evaluated by means of the
variance analysis by the F test. Based on the variance
analysis, the treatment squares were decomposed in
general (GCA) and specific (SCA) combining ability.
For the decomposition, Griffing’s method 4 was used
in the fixed model (Griffing 1956). All analyses were
completed using the software Genes (Cruz 2006).
Results and discussion
Seed quality traits
All seed quality traits were significant by the F test
(Tables 2), indicating that there is sufficient genetic
variability in the diallel (genitors and hybrids), which
is of fundamental importance for obtaining genetic
gains in hybrid combinations. The low coefficients of
variation values for the evaluated traits confirm the
greater confidence in the obtained results (Tables 2).
Unfolding the sum of the genotype squares to the
general (GCA) and specific (SCA) combining ability
revealed that all of the traits were significant by the
F test (Table 2). The significant mean squares reveal
the existence of variability resulting from additive and
dominant effects in the control of genetic expression.
The quadratic components associated with the
SCA effect were greater than those associated with
the GCA for all traits evaluated, which revealed the
greater importance of the dominance effects
(Table 2). These results agree with those obtained
by Gomes et al. (2000), who verified higher magni-
tudes for the dominance effect when studying the
combining ability of common tropical corn lines for
seed quality using the same tests as used in the
present study.
Table 2 Estimates of mean squares of 36 hybrids for general (GCA) and specific (SCA) combining abilities, residual effects and
quadratic components of GCA (U2g) and SCA (U2
s ) related to eight quality of seeds evaluated in diallel
Sources of variation DF Mean squares DF Mean squares
IC GER ACC COLD ECO SE ES ESI
Genotypes 35 314.31** 144.13** 35 102.31** 146.06** 26.04** 64.06** 0.11** 1.01**
GCA 8 512.64** 284.77** 8 164.50** 344.05** 63.84** 161.28** 0.19** 2.39**
SCA 27 255.58** 102.47** 27 83.88** 87.40** 14.83** 35.25** 0.09** 0.61**
Error 252 20.52 11.83 108 24.10 21.23 2.63 8.09 0.01 0.10
Quadratic components
U2g
8.79 4.87 5.01 11.53 2.19 5.47 0.006 0.08
U2s
29.38 11.33 14.94 16.54 3.05 6.79 0.020 0.13
U2g/U2
s0.30 0.43 0.33 0.70 0.72 0.81 0.30 0.61
CV2/ 5.42 3.68 5.69 5.38 11.78 2.98 2.19 3.60
IC first count of germination test, GER germination test, ACC accelerated aging (%), COLD modified cold (%), ECO electrical
conductivity (lS cm-1 g-1), SE seedling emergence in sand seedbed (%), ES speed of emergence (days); and ESI speed of
emergence index. CV coefficient of variation
** Significant by the F test at 1% probability
340 Euphytica (2012) 185:337–347
123
However, these results were discordant with those
obtained by Barla-Szabo et al. (1989) for common
corn, in the inheritance of seed vigour primarily
occurred due to the additive effect of genes. Antuna
et al. (2003) also verified that the additive effect was
proportionally of greater importance in the expression
of the seed quality in common corn.
Through the estimates of the general combining
effects (gi), the CMS43-1 and UEM-J1 lines revealed
positive gi effects for the first and final counts in the
germination test (IC and GER, respectively) (Table 3).
The UEM-J1 line was also highlighted by the ACC,
COLD and ECO tests as having greater ACC and
COLD test estimates and lower ECO estimates.
Therefore, it is noted that in the seed vigour evaluation
through the IC, GER, ACC and COLD tests, the UEM-
J1 line stood out. It had greater tolerance to adverse
temperature and humidity conditions, which is of
interest for cultivation in two different cultivation
seasons, one with rainy and other with dry conditions.
The lowest gi estimate observed for ECO indicates that
the line was superior to the rest as a function of the
lower degree of seed deterioration and, consequently,
through greater vigour.
The Zelia and CMS 42 lines revealed greater gis
estimates for the SE and ESI tests, while for the ES
test, the same lines stood out by expressing lower
estimates, thus contributing to a reduction in the
seedling emergence period. In relation to the UEM-J1
line, the gis values were lower in magnitude for SE,
ES and ESI (Table 3).
With regard to the specific combining ability, the
CMS 42-1 9 IAC-112, Zelia 9 Zaeli, Zelia 9 IAC-
112, UEM M2-1 9 Zaeli and CMS 43-2 9 UEM-J1
hybrids revealed the major positive sij effects for the
first and final counts in the germination tests (IC and
GER, respectively) (Table 4). In the ACC and COLD
tests, Zelia 9 CMS 43-2, Zelia 9 UEM M2-2, CMS
42-1 9 CMS 43-2, CMS42-1 9 UEM M2-1, UEM-
J1 9 UEM M2-2 and UEM-J1 9 Zaeli hybrids pre-
sented the greatest sij estimates, respectively.
The CMS 42-1 9 IAC-112, Zelia 9 UEM M2-2
and UEM-J1 9 Zaeli hybrids had the smallest ECO
sij. Regarding to the SE test, the best combinations
were CMS 42-1 9 IAC-112, UEM-J1 9 UEM M2-2
and UEM-J1 9 Zaeli (Table 4).
The ES test, translating for greater uniformity in
the establishment of the cultures based on the lower
sij estimates, revealed the UEM-J1 9 UEM M2-1,
CMS 42-1 9 CMS 43-1 and Zelia 9 IAC-112 com-
binations as the most promising to establish fast
production, avoiding costs and contaminations with
use of herbicides. The UEM-J1 9 UEM M2-1 hybrid
also stood out for the best ESI test estimate (Table 4).
Agronomical traits
There was significance by the F test for all the
evaluated agronomical traits (Table 5), showing the
variability between genotypes. There was also dif-
ferentiated behaviour of the evaluated genotype set
(G) in the two growing seasons (S) based on G 9 S
significance, revealing the opportunity to indicate the
superior hybrids for both seasons. This is particularly
important in relation to the atypical growing season
(second crop), because this allows expansion of the
popcorn cultivation in the same area, in seasons not
normally recommended for harvest, thus contributing
to enhanced productivity without harming land not
previously used for this production.
With regard to estimated variation of general and
specific combining ability, no significance was found
for the HFI and PE traits, revealing that there was no
resultant variability of the dominance and additive
effects, respectively, for these traits. The significance
of the other traits indicates that additive and domi-
nance effects control the genetic action. The mean
squares of GCA 9 S were significant for PH, GY and
PE, whereas, for SCA 9 S, there were significant
differences for PH, HDI and PE (Table 5). These
results indicate that the HFI trait uncovers a reduced
distinguishing behaviour of the parents in the 2008/09
and 2009 agricultural seasons, allowing for global
analysis of the estimates assumed by the estimator gi
in both the agricultural seasons. In relation to the GY
trait, this did not exhibit significance for the
SCA 9 S factor, which indicates the permitting
estimate of sij in both agricultural seasons.
The Zelia, CMS 43-2, UEM-M2-1 and UEM M2-2
lines expressed negative gi values for pH in both
agricultural seasons, indicating that these genotypes
contribute to reduced plant height. The UEM
M2-2 parent was distinguished by its lower gi effect
(-12.69 and -12.83, for the first and second growing
seasons, respectively).
The effect of GCA for HFI can be analysed
together for both growing seasons. Thus, the average
gi for HFI revealed that the UEM M2-2, UEM M2-1,
Euphytica (2012) 185:337–347 341
123
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342 Euphytica (2012) 185:337–347
123
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3.8
4-
8.5
50
.13
-0
.50
0.2
1-
0.3
8-
0.3
70
.14
0.6
40
.37
80
.77
4.2
12
.05
P1
9P
73
.05
1.0
04
.37
3.6
6-
2.8
70
.14
0.1
2-
0.1
6-
4.0
7-
4.8
30
.62
-4
.69
27
.61
-0
.14
-2
.52
P1
9P
89
.02
4.4
6-
2.1
22
.80
-0
.99
0.7
8-
0.1
40
.33
5.5
42
.00
3.6
01
.96
21
6.5
7-
1.1
10
.37
P1
9P
97
.73
5.6
82
.95
2.8
0-
0.9
72
.93
-0
.20
0.5
84
.68
0.1
41
0.7
1-
1.7
11
81
.35
0.9
31
.35
P2
9P
30
.09
-2
.18
-1
.91
-2
.05
0.9
7-
2.5
7-
0.2
80
.19
-5
.06
-1
1.5
5-
2.0
1-
3.8
91
07
.92
-2
.34
0.9
2
P2
9P
4-
1.8
41
.43
4.1
64
.37
0.0
53
.00
-0
.18
0.5
22
.14
-2
.12
1.4
9-
7.9
0-
18
1.9
6-
0.2
4-
1.0
5
P2
9P
53
.12
-1
.03
-2
.34
-2
.98
-0
.03
-0
.28
0.0
6-
0.1
15
.23
-5
.72
7.3
7-
0.0
6-
14
2.2
51
.68
0.8
4
P2
9P
6-
3.8
71
.93
7.5
22
.87
-1
.42
-0
.86
0.2
0-
0.4
4-
0.2
25
.10
-1
.70
4.7
42
85
.71
3.5
10
.20
P2
9P
7-
4.4
1-
1.7
1-
6.7
7-
3.9
10
.14
-0
.71
0.0
8-
0.1
03
.58
4.9
5-
1.0
65
.55
-1
22
.18
0.4
30
.69
P2
9P
80
.05
2.0
0-
0.7
74
.73
0.2
91
.43
0.0
70
.05
6.9
70
.46
7.1
4-
2.7
3-
20
.61
2.2
3-
0.8
1
P2
9P
91
1.0
24
.21
6.3
0-
0.2
6-
4.3
34
.57
0.0
10
.40
-3
.74
9.6
6-
1.1
96
.41
37
9.1
1-
1.5
5-
2.9
5
P3
9P
43
.12
2.3
6-
1.9
14
.16
-1
.56
1.8
6-
0.0
00
.13
-1
0.3
6-
16
.25
-7
.97
-1
3.4
6-
95
1.7
1-
0.8
7-
1.8
3
P3
9P
53
.34
-0
.61
8.0
9-
1.2
0-
1.5
5-
0.9
30
.17
-0
.33
-5
.95
5.4
76
.91
-5
.09
17
9.0
03
.08
-0
.61
P3
9P
6-
0.4
10
.36
-2
.05
0.1
6-
0.8
31
.50
-0
.10
0.3
19
.03
20
.69
7.9
61
3.6
87
03
.51
-0
.53
0.0
4
P3
9P
7-
2.9
7-
0.7
8-
7.3
4-
0.6
2-
1.1
5-
1.8
60
.06
-0
.25
3.6
02
.22
3.2
03
.59
-31
0.6
82
.58
2.9
6
P3
9P
80
.27
1.4
30
.66
-0
.48
0.2
01
.78
0.0
90
.03
6.0
83
.58
-1
.15
6.4
93
7.1
3-
3.3
70
.58
P3
9P
9-
1.5
23
.14
0.7
32
.02
0.8
00
.93
0.0
40
.03
-3
.29
-1
.68
-5
.95
-2
.50
26
3.5
10
.90
1.7
2
P4
9P
54
.41
3.2
5-
4.3
4-
3.2
70
.80
-2
.86
0.0
1-
0.2
7-
1.4
8-
5.3
60
.33
-3
.28
-6
32
.79
1.9
43
.36
P4
9P
6-
0.8
4-
3.5
3-
2.4
8-
4.9
1-
0.2
1-
4.4
3-
0.0
1-
0.3
61
.23
-2
.34
-2
.64
1.8
02
15
.47
-0
.39
3.2
8
P4
9P
7-
0.6
2-
0.4
34
.23
-5
.70
0.1
3-
1.2
8-
0.0
70
.00
2.8
22
2.3
70
.03
11
.95
15
3.1
31
.60
-0
.62
P4
9P
8-
7.4
1-
6.4
6-
0.7
7-
2.0
52
.08
-0
.64
0.0
7-
0.1
73
.23
-9.2
04
.36
-5
.54
43
3.3
7-
0.5
5-
1.4
6
P4
9P
90
.80
1.0
0-
3.7
04
.45
0.5
21
.50
0.2
4-
0.2
13
.23
1.0
6-
0.7
75
.69
78
9.4
9-
1.6
4-
0.5
4
P5
9P
60
.87
1.0
0-
0.9
85
.23
1.6
11
.78
-0
.33
0.6
7-
3.7
05
.60
-4
.22
3.4
6-
14
5.5
6-
2.8
00
.00
P5
9P
70
.59
2.6
14
.23
3.9
50
.31
3.9
30
.01
0.3
43
.18
-0
.52
1.4
31
.83
-1
33
.31
0.1
3-
0.9
6
Euphytica (2012) 185:337–347 343
123
Ta
ble
4co
nti
nu
ed
Hy
bri
ds
Ev
alu
ated
trai
ts
See
dq
ual
ity
Ag
ron
om
ical
ICG
ER
AC
CC
OL
DE
CO
SE
ES
ES
IP
HH
FI
GY
PE
20
08
/09
20
09
20
08
/09
20
09
Join
t2
00
8/0
92
00
9
P5
9P
81
.55
3.0
73
.23
6.0
9-
2.4
93
.57
-0
.03
0.3
9-
3.0
57
.64
-1
.56
10
.66
72
8.7
3-
1.3
8-
1.0
1
P5
9P
9-
6.7
3-
5.7
1-
4.2
0-
8.9
12
.31
-4
.28
0.1
0-
0.5
87
.77
-1
.10
-0
.56
-1
.82
49
3.0
8-
1.8
1-
3.1
5
P6
9P
73
.84
-0
.18
-1
.41
4.8
01
.54
-0
.14
0.1
0-
0.1
7-
13
.19
-3
1.6
7-
6.6
0-
17
.66
-2
44
.90
-4
.14
-5
.20
P6
9P
87
.55
2.5
32
.09
0.4
50
.26
1.5
00
.04
0.0
92
.70
-0
.14
1.5
1-
5.3
8-
28
9.9
0-
0.1
7-
0.7
6
P6
9P
91
.77
0.5
01
.16
-0
.05
-1
.08
1.1
4-
0.1
00
.28
4.5
22
.63
5.0
5-
1.0
1-
60
5.1
00
.31
0.3
8
P7
9P
81
.27
0.6
41
.80
-6
.84
-0
.10
-0
.86
-0
.15
0.0
6-
2.1
16
.92
-2
.12
-0
.48
51
3.2
40
.51
2.7
8
P7
9P
9-
0.7
7-
1.1
40
.87
4.6
61
.99
0.7
8-
0.1
50
.28
6.1
90
.56
4.5
0-
0.0
81
17
.09
-0
.98
2.8
7
P8
9P
9-
12
.30
-7
.68
-4
.12
-4
.70
0.7
5-
7.7
50
.06
-0
.79
-1
9.3
5-
11
.27
-1
1.8
0-
4.9
7-
16
18
.54
3.8
30
.31
SD
1.3
91
.05
2.1
31
.99
0.7
01
.23
0.0
40
.14
3.6
65
.15
3.7
03
.89
26
7.4
51
.13
1.3
2
ICin
itia
lco
un
t(%
),G
ER
fin
alg
erm
inat
ion
cou
nt
(%),
AC
Cac
cele
rate
dag
ing
(%),
CO
LD
mo
difi
edco
ld(%
)E
CO
elec
tric
alco
nd
uct
ivit
y(l
Scm
-1
g-
1),
SE
seed
lin
gem
erg
ence
insa
nd
seed
bed
(%),
ES
spee
do
fem
erg
ence
(day
s),
ES
Isp
eed
of
emer
gen
cein
dex
,P
Hp
lan
th
eig
ht
(cm
),H
FI
hei
gh
to
fth
efi
rst
ear
inse
rtio
n(c
m),
GY
gra
iny
ield
(kg
ha-
1),
and
PE
po
pp
ing
exp
ansi
on
(ml
g-
1).
P1
Zel
ia,
P2
CM
S4
2-1
,P
3C
MS
43
-1,
P4
CM
S4
3-2
,P
5U
EM
-J1
,P
6U
EM
M2
-1,
P7
UE
MM
2-2
,P
8Z
aeli
,an
dP
9IA
C-1
12
.S
Dst
and
ard
dev
iati
on
344 Euphytica (2012) 185:337–347
123
CMS 43-2 and CMS 43-1 parents tended to provide a
greater genetic accumulation for reduced ear height
in the two studied harvests. In the study by Ji et al.
(2006), the ear height insertion was one of the traits
of greatest importance in corn selection programs
because it was directly related to lodging, especially
of popcorn in relation to common corn, because it is
more fragile than common corn.
With regard to GY, the UEM-J1, CMS 42-1, IAC-
112 and CMS 43-1 parents had positive gi values in the
2008/09 and 2009 agricultural seasons, with the UEM-
J1 (1163.35) and CMS 42-1 (229.44) parents having
more elevated gis values in the 2008/09 harvest, and
UEM-J1 (664.90) followed by IAC-112 (228.36), in
the 2009 harvest, which indicates the increased genetic
contribution for grain yield in the participating crosses.
In relation to the PE, the estimated gi effects
showed that Zelia, CMS 42-1, UEM M2-2, Zaeli and
IAC-112 had the capacity to synthesise greater
hybrids in the two agricultural seasons, indicating
the greater frequency of favourable alleles for
popping expansion in relation to the other evaluated
lines. It is worth noting that the Zelia and CMS 42–1
lines, in addition to exceeding the PE, were also
favourable for popcorn seed quality, had elevated gi
positive for the GER, COLD, SE and ESI tests and
negatives for ES. This factor must be taken into
consideration, as the seed quality is fundamental in
the sowing process of any culture.
The joint analysis of the average SCA estimates for
the PH trait revealed that the UEM M2-1 9 UEM M2-
2, CMS 43-1 9 CMS 43-2 and Zelia 9 CMS 42-2
combinations had the greatest negative sij values in the
2008/09 cultivation season, and the UEM M2-
1 9 UEM M2-2, CMS 43-1 9 CMS 43-2, CMS
43-2 9 Zaeli and Zelia 9 UEM-J1 combinations
had the greatest negative sij values in the 2009
agricultural season. In the HFI trait, the CMS 43-1 9
CMS 43-2 and UEM M2-1 9 UEM M2-2 combina-
tions had a greater SCA in the 2008/09 harvest.
Furthermore, in the 2009 harvest, the CMS 43-1 9
CMS 43-2, UEM M2-1 9 UEM M2-2 and CMS
42-1 9 CMS 43-2 hybrids were highlighted (Table 4).
With regard to the GY trait, combinations whose
sij values were positive and elevated were identified.
This revealed hybrids that tended to contribute to
increased grain yield. Thus, as there was no interac-
tion between seasons, the SCA for GY can be
analysed together. Hierarchically, the best combina-
tions were CMS 43-2 9 IAC-112, UEM-J1 9 Zaeli,
CMS 43-1 9 UEM-M2-1, UEM-M2-2 9 Zaeli and
UEM-J1 9 IAC-112 (Table 4).
When comparing the obtained results with those
relative to the seed quality, one notices that the UEM-
J1 9 Zaeli combination, in addition to exceeding
GY, demonstrated good quality in the cold test. The
CMS 42-1 9 IAC-112 hybrid, despite not having the
greatest estimate, was highlighted for presenting high
Table 5 Mean squares estimates of the general (GCA) and
specific (SCA) combining abilities for 36 hybrids, as well
growing seasons (S) and interactions with genotypes of
popcorn (G) for four agronomical traits evaluated in a complete
diallel during the 2008/2009 and 2009 growing seasons
Source of variation GL Mean squares
PH HFI GY PE
Genotypes (G) 35 897.69* 535.76* 3371529.55* 114.26**
GCA 8 2699.70* 1733.61* 8945764.96* 428.99ns
SCA 27 363.76* 180.84ns 1719904.26* 21.00ns
Seasons (S) 1 78064.94 27517.35 709588490.12 3211.29
G 9 S 35 147.93* 90.66** 540274.38* 39.09*
GCA 9 S 8 181.18** 65.58ns 1154399.97* 132.40*
SCA 9 S 27 138.07** 98.10** 358311.23ns 11.44**
Error 110 79.95 57.61 286119.71 6.04
PH plant height (cm), HFI height of the first ear insertion (cm), GY grain yield (kg ha-1), and PE popping expansion (ml g-1)
ns not significant at the 0.05 level
**Significant at the 0.01 level
*Significant at the 0.05 level
Euphytica (2012) 185:337–347 345
123
sij estimates for GY and was also noted for presenting
the best estimates in the ECO and SE tests and for
good performance in the GER, ACC and ESI tests.
In the 2008/09 agricultural season, the Zelia 9
UEM M2-1, CMS 42-1 9 UEM-J1, CMS 42-1 9
UEM M2-1, CMS 42-1 9 Zaeli, CMS 43-1 9 UEM
M2-2 and Zaeli 9 IAC-112 combinations had the
greatest positive sij values for PE. In the 2009
agricultural season, the greatest values occurred in
the following hybrids: Zelia 9 CMS 42-1, Zelia 9
UEM M2-1, CMS 43-1 9 UEM M2-2, UEM M2-
2 9 Zaeli and UEM M2-2 9 IAC-112.
The Zelia 9 UEM M2-1, CMS 43-1 9 UEM M2-2
hybrids are of interest for cultivation in both environ-
ments, and are therefore of interest for tropical
environment (in the 2008/09 harvest season) and for
the second harvest agricultural season (2009), where
there is a mild winter at harvest time. These hybrids are
interesting for cultivation during rainy and dry seasons,
what makes possible to cultivate popcorn in different
climate conditions. The ideal recommendation is
Zelia 9 UEM M2-1 for rainy season (regular cultiva-
tion period) and Zelia 9 CMS 42-1 for the dry season
with cooler temperatures, which was represented by
the second harvest season, where winter occurs in the
final culture phase. Another viable alternative is the
handling crop rotation, using Zelia 9 CMS 42–1 in
the second harvest culture season.
To compile desirable traits in one hybrid, one could,
using restrictive logic, recommend the Zelia 9 IAC-
112, CMS 43-1 9 IAC-112 and UEM M2-2 9 Zaeli
combinations for their elevated GY estimates and
positive PE. However, for a more complete analysis,
one can note that the Zelia 9 UEM M2-1, CMS
42-1 9 UEM M2-1 and UEM M2-2 9 Zaeli con-
tained the greatest sij estimates for PE in at least one
harvest and did not reveal mean estimate values
undesirable for GY. It must be emphasised that the sij
estimates for the UEM M2-2 9 Zaeli pair for GY was
ranked as the fourth greatest.
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