Maize Genetics Cooperation Newsletter vol 81 2007
During the growing season 2005/06, twenty single cross hybrids, generically termed CIG, and their parents were evaluated in a completely randomized blocks field trial design (three replicates) at the Instituto Fitot�cnico de Santa Catalina and CIGEN placed in the location of Llavallol province of Buenos Aires, Argentina (22 m.a.s., 34� 48�S; 58� 31�W). Genotypes were evaluated for minimun potential yield expressed in kilograms/hectare (Y), ear weight (EW), kernel weight per ear (KWE) and cob percentage (% C). All genotypes evaluated were developed within a maize quality breeding program initiated during the 90�s. Yield was calculated as follows:
Y= average kernels weight per ear x 71,500 plant per hectare
High parent heterosis (%) was determined for each trait mentioned according to the formula:
HP % = F1 - HP x 100
HP
(F1: single cross value; HP: high-parent value)
The single
crosses may be divided into three groups: 1) wx1, 2) o2 and 3) double
recessive (wx1 o2 hybrids). Minimum yield varies from 5,326 kg/ha to
8,701 kg/ha for the hybrids CIG133, CIG141, CIG144, CIG158, CIG159 and
CIG161. Significant HP heterosis values (%) were found for yield in these hybrids
(102.0% to 169.9%; Table 1). Two
hybrids (CIG109: 3,632 kg/ha and
Table 1. High
Parent heterosis (%) of single cross hybrids.
|
Genotype |
Hybrid |
EW |
KWE |
% C |
Yield |
|
wx1 |
CIG46 |
2.0 |
3.2 |
-39.9 |
3.2 |
|
CIG67 |
32.3 |
35.6 |
-23.3 |
35.5 |
|
|
CIG25 |
100.0 |
20.0 |
-39.4 |
20.1 |
|
|
CIG70 |
82.6 |
90.9 |
-18.2 |
90.9 |
|
|
CIG77 |
58.1 |
63.8 |
-14.6 |
64.0 |
|
|
CIG141 |
123.8 |
169.9 |
-37.1 |
169.9 |
|
|
o2 |
CIG186 |
35.4 |
39.8 |
-14.6 |
40.0 |
|
CIG8 |
18.8 |
13.3 |
-34.3 |
13.3 |
|
|
CIG10 |
45.8 |
40.4 |
-7.3 |
40.4 |
|
|
CIG187 |
-20.6 |
-19.8 |
-12.2 |
-19.8 |
|
|
CIG159 |
88.4 |
114.7 |
-32.6 |
114.7 |
|
|
CIG3 |
29.0 |
38.1 |
-47.7 |
38.1 |
|
|
CIG109 |
-41.9 |
-38.8 |
-20.0 |
-38.8 |
|
|
wx1 o2 |
CIG82 |
33.5 |
31.3 |
-17.1 |
44.5 |
|
CIG127 |
-3.4 |
2.8 |
-22.2 |
2.8 |
|
|
CIG133 |
74.2 |
109.0 |
-38.5 |
102.0 |
|
|
CIG144 |
104.4 |
151.1 |
-44.5 |
151.3 |
|
|
CIG158 |
112.8 |
167.8 |
-50.4 |
168.1 |
|
|
CIG161 |
135.7 |
148.9 |
-36.0 |
148.9 |
|
|
CIG164 |
4.1 |
8.6 |
-24.2 |
8.7 |
CIG187: 4,762 kg/ha), obtained by crossing very closely related inbreds, showed negative HP heterosis
values for all the traits as were.
All hybrids showed a negative HP heterosis
value for % C. This is due to the
fact that the hybrid ears are completely fertile whilst the inbreds
normally lack some kernels.
Correlation between yield and kernel weight per ear is highly
significant (r: 0.99; p: 0.01) and the regression equation between these
parameters is Y: 0.887 + 0.99(KWE).
In contrast, the correlation coefficient between yield
and ear weight (including cob weight), is significant; it is lower (r: 0.83; p:
0.01). As seen in Table 2, the
highest hetero-
Table 2. Average HP heterosis for
different groups of hybrids.
|
Genotype |
EW |
KWE |
% C |
Yield |
|
wx1 |
66.41 |
63.89 |
-28.74 |
63.94 |
|
o2 |
22.12 |
26.8 |
-24.1 |
26.84 |
|
wx1 o2 |
65.89 |
88.5 |
-33.26 |
90.46 |
sis values for Y and KWE were found in the double-recessive hybrids. Yields varied from 3,331 kg/ha for CIG109 to 9,404 kg/ha for the waxy hybrid CIG70. Considering that these single crosses carry one or two mutant genes usually associated with lower yield, the high HP heterosis values and minimum potential yield found in some makes them candidates for commercial release.
Please Note: Notes submitted to the Maize Genetics Cooperation
Newsletter may be cited only with consent of authors.