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.

 

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of authors.