Maize Genetics Cooperation Newsletter vol 81 2007
SIMNIC-CRAIOVA, ROMANIA
University of Craiova
Studies concerning the heredity of some characteristics of the corncob
--Bonea, D; Urechean, V
The great productivity of corn relies heavily on heterosis. In this paper we explore heterosis with the potential to contribute to the creation of valuable new corn hybrids. We performed direct diallel hybridization of five corn inbred lines and analyzed certain characteristics of the corncob in the simple hybrids. We evaluated heterosis using capacity relation ( CR) calculated using the formula of M. Jost (1976):
CR=F1-Max.P where Max P is maximum parental value.
1(P2-P1)
2
We found (Table) strong heterosis for all the characteristics of the corncob most notably the weight of the corncob for Lc406x Lc407 (222g) and Lc402xLc406 (215.7g) hybrids; the length of the corncob for Lc402xLc 406 (8.35 cm) and Lc402xLc407 (6.5 cm) hybrids; and the number of grains/corncob for Lc402xLc406 (524) and Lc406xW153R (444.5). Our data shows that there is no heterosis effect in the number of grains per corncob for Lc403xLc407 (-77.5) and Lc407xW153R (-7.0) hybrids.
Table
1. The
difference between F1 and parent�s average and capacity relation of some simple
corn hybrids.
|
No. |
Hybrid |
Corncob
weight (g) |
Corncob
length (cm) |
Number
of grains per corncob |
|||
|
F1- |
CR |
F1- |
CR |
F1- |
CR |
||
|
1 |
Lc403xLc402 |
26.5 |
+0.74 |
5.05 |
-0.83 |
205 |
-0.68 |
|
2 |
Lc406xLc402 |
193 |
+26.57 |
5.75 |
-22.0 |
428 |
+1.56 |
|
3 |
Lc407xLc402 |
195 |
-194 |
5.7 |
-3.38 |
166.5 |
+29.2 |
|
4 |
W153RxLc402 |
138 |
-5.43 |
3.8 |
-1.11 |
147.5 |
+1.47 |
|
5 |
Lc402xLc403 |
86 |
-0.15 |
3.25 |
+0.18 |
167 |
+0.36 |
|
6 |
Lc406xLc403 |
137.5 |
+0.28 |
2.3 |
-0.08 |
252 |
-0.13 |
|
7 |
Lc407xLc403 |
68.8 |
-0.31 |
3.55 |
+1.46 |
48.5 |
-0.62 |
|
8 |
W153RxLc403 |
34.2 |
-0.46 |
1.06 |
+0.10 |
137.5 |
-0.24 |
|
9 |
Lc402xLc406 |
215.7 |
+27.8 |
8.35 |
+32.4 |
524 |
-2.43 |
|
10 |
Lc403xLc406 |
92.5 |
+0.14 |
3.6 |
-0.44 |
202 |
+0.30 |
|
11 |
Lc407xLc406 |
155.3 |
-18.4 |
2.05 |
-0.95 |
286.5 |
-0.77 |
|
12 |
W153RxLc406 |
135.4 |
-2.07 |
2.55 |
-0.64 |
391.5 |
-2.64 |
|
13 |
Lc402xLc407 |
207 |
+206 |
6.5 |
+4.0 |
283.5 |
-50.5 |
|
14 |
Lc403xLc407 |
74.5 |
+0.25 |
0.55 |
+0.62 |
-77.5 |
+1.60 |
|
15 |
Lc406xLc407 |
222 |
+26.75 |
4.95 |
+3.71 |
384.5 |
+1.38 |
|
16 |
W153RxLc407 |
158 |
-3.38 |
3.5 |
-6.0 |
231 |
+3.27 |
|
17 |
Lc402xW153R |
187.8 |
+4.07 |
5.8 |
+2.22 |
324.5 |
-4.45 |
|
18 |
Lc403xW153R |
64.5 |
-0.02 |
4.25 |
-3.47 |
98.5 |
+0.45 |
|
19 |
Lc406xW153R |
147 |
+2.34 |
5.95 |
+2.83 |
444.5 |
+3.13 |
|
20 |
Lc407xW153R |
129.5 |
+2.59 |
2.50 |
+4.0 |
-7.0 |
-1.12 |
In summary, we find that for corncob weight, eleven hybrids are positive for heterosis and nine are negative; for corncob length, ten hybrids are positive and ten are negative; for the number of grains per corncob, ten hybrids are positive and ten are negative. Positive hybrids are considered to be valuable and will be promoted through improvement programs.
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