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Triticeae Genomics and Genetics 2013, Vol.4, No.2, 3
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5
The performance of the hybrid generations compared
to the parents is presented in Table 2, where a high
magnitude and positive sign was found for the
characters GY P
-1
and PP in all crosses. The maximum
expression of vigor was observed for CR1 (120.96%
and 82.68%, for GY P
-1
and PP, respectively),
revealing a large decrease when comparing the F2 and
F
1
generation means. Regarding the character NP P
-1
,
a reduced heterosis expression was observed, except
for CR1, which showed positive values. Based on the
genetic parameters of each population, a high and
distinct phenotypic variance (σ
P
2
) was observed for
each of the different crosses analyzed and for the three
target characters (Table 2). When compared the values
of σ
G
2
and σ
E
2
, it can be observed a lower contribution
of the environment (σ
E
2
) for the total phenotypic
variance (σ
P
2
). The additive variance (σ
A
2
) was, in
general, the major genetic effect on the genetic
variance (σ
G
2
). Regarding the character GY P
-1
, the
crosses presented a distinct behavior for σ
P
2
and σ
G
2
values, however, the variance attributed to the genetic
effects (σ
G
2
) expressed higher magnitude when
compared to σ
E
2
for all crosses. The most significant
contribution of σ
D
2
(60%) to σ
G
2
for the character GY
P
-1
, was found in CR3. In this case, the σ
A
2
(40%)
resulted in the highest value found for the broad sense
heritability (h
a
2
), reaching 73.18%. Regarding σ
A
2
, the
major contribution of this component was found in
CR1, reaching 83% of σ
G
2
, therefore overcoming the
dominance variance (σ
D
2
), leading to a higher h
r
2
(53.08%). The higher values for σ
G
2
found for the
character NP P
-1
were obtained in CR1, where a large
contribution from σ
D
2
was also detected. The cross
CR5 (UPF 18/UFRGS 17), revealed that 76% of σ
G
2
was due to σ
D
2
, showing a reduced h
r
2 (13.90%). Only
the crosses CR3 and CR4 (UPF 18/UFRGS 7), reveal-
ed a superior effect of σ
A
2
over σ
D
2
, and consequently
higher h
r
2
. The character PP in cross CR5 was the only
case to show negative σ
D
2
values. Its values were
recalculated in order to eliminate the error estimates
caused by super estimating the additivity. The same
character showed, in crosses CR4 and CR5, the higher
σ
A
2
values.
Table 2 Phenotypic (σ
P
2
), genetic (σ
G
2
) and environment (σ
E
2
) variance, additive (σ
A
2
), dominance (σ
D
2
), broad (
h
a 2
) and strict (
h
r
2
)
sense heritability and heterosis (H) and loss of vigor (LV) estimates for three characters in five oat crosses (CR)
Note: CR1 (UPF 16/UPF 18); CR2 (UPF 16/UFRGS 7); CR3 (UPF 16/URPEL 15); CR4 (UPF 18/UFRGS 7); CR5 (UPF 18/UFRGS 17)
σ
P
2
σ
G
2
σ
E
2
σ
A
2
σ
D
2
h
a 2
h
r
2
H
LV
Cross
Grain yield per plant (GY P
-1
)
CR1
14.16
9.00
5.15
7.51
1.48
63.58
53.08
120.96
34.73
CR2
12.27
6.61
5.65
3.04
3.57
53.90
24.78
42.52
22.54
CR3
17.16
12.56
4.60
5.08
7.47
73.18
29.64
15.89
8.27
CR4
10.58
5.45
5.13
3.73
1.72
51.52
35.28
11.78
10.90
CR5
9.40
4.79
4.60
3.99
0.79
50.99
42.49
17.73
5.82
Number of panicles per plant (NP P
-1
)
CR1
8.53
6.17
2.36
2.26
3.90
72.25
26.52
4.91
12.89
CR2
7.36
4.48
2.88
1.73
2.74
60.82
23.54
-22.75
10.09
CR3
5.24
3.60
1.64
2.56
1.03
68.62
48.92
-25.00
-0.45
CR4
5.10
3.20
1.90
2.01
1.18
62.78
39.50
-24.12
12.45
CR5
3.32
1.97
1.34
0.46
1.51
59.48
13.90
-7.80
-7.05
Panicle weight per plant (PP)
CR1
2.43
1.76
0.67
1.32
0.43
72.27
54.46
82.68
21.49
CR2
1.62
1.17
0.44
0.79
0.38
72.61
49.03
59.74
9.60
CR3
1.81
1.33
0.48
0.55
0.77
73.35
30.53
36.30
0
CR4
2.63
2.06
0.56
1.69
0.37
78.63
64.38
34.61
6.42
CR5
4.19
3.54
0.65
1.72
1.82
84.48
41.05
46.11
15.78