MNL306.DOC

 

LLAVALLOL, ARGENTINA

 

 

INSTITUTO FITOTECNICO DE SANTA CATALINA, FACULTAD DE CIENCIAS AGRARIAS Y FORESTALES, UNIVERSIDAD NACIONAL DE LA PLATA AND CIGEN (CONICET-CIC-UNLP)

 

HETEROSIS % OF YIELD TRAITS IN QUALITY MAIZE SINGLE-CROSS HYBRIDS DEVELOPED IN ARGENTINA

 

Corcuera VR1, BernatenŽ EB2, Poggio L2

 

1C.I.C.    2 CONICET

 

During the growing season 2005/06, at the Instituto FitotŽcnico 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) twenty single-cross hybrids, -generically termed CIG-, and their parents were evaluated in a completely randomized blocks field trial design (three replicates) by their minimun potential yield expressed in kilograms/hectare (Y), ear weight (EW), kernels weight per ear (KWE) and cob percentage (%C). All the 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 traits mentioned according to the formula:

 

                               HP %  =  F1  -  HP   x   100

                                                   HP

 

                                     (F1: single-cross value; HP: high-parent value)

 

 

According to their genotype, the single-crosses may be divided into three groups: 1. Waxy, 2. Opaque-2 and 3. Double recessive (wxo2 hybrids).    Minimun potential 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%) (see Table 1). Two hybrids (CIG109; 3,632 kg/ha) and (CIG187; 4,762 Kg/ha) showed negative HP-heterosis values for all the traits as were obtained by crossing very closely related inbreds.  All the hybrids show a negative HP-heterosis value for %C. This is due to the fact that the hybrid«s ears are completely fertile whilst the inbreds normally lack some kernels. Correlation between yield and kernels 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). Instead, the correlation coefficient between yield and ear weight (that includes cob«s weight), whether significant is lower (r: 0.83; p: 0.01). As may be seen in Table 2, the highest heterosis values for Y and KWE were found in the double-recessive hybrids. Yields ranked from 3,331 kg/ha (CIG109) to 9,404 kg/ha of the waxy hybrid termed CIG70.  Considering that these single-crosses carry one or two mutant genes, usually responsible of lower yieldings, the high HP-heterosis values and minimun potential yield  found in some of them in this field experiment let us think about the future posibility of commercially  releasing them to the market.

 

 

Table 1: High-Parent heterosis (%) of  single-cross hybrids.

 

 

 

 

 

 

TYPE

HYBRID

EW

KWE

%C

YIELD

Waxy

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

Opaque2

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

wxo2

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

 

 

 

 

Table 4: Average HP-heterosis for different groups of hybrids.

 

 

 

 

 

 

 

 

 

 

Tipo

PE

PG

%M

Rinde

WX

66,41

63,89

-28,74

63,94

o2

22,12

26,8

-24,1

26,84

DR

65,89

88,5

-33,26

90,46