Two-locus theory in recurrent selection for general combining ability in maize

1982 ◽  
Vol 61 (3) ◽  
pp. 279-283 ◽  
Author(s):  
G. R. Johnson
Keyword(s):  
Combining Ability ◽  
Recurrent Selection ◽  
General Combining Ability ◽  
Selection For

scholarly journals Parent selection for cocoa resistance to witches'-broom

2010 ◽  
Vol 45 (7) ◽  
pp. 680-685 ◽  
Author(s):  
Stela Dalva Vieira Midlej Silva ◽  
Edna Dora Martins Newman Luz ◽  
José Luis Pires ◽  
Milton Macoto Yamada ◽  
Lindolfo Pereira dos Santos Filho
Keyword(s):  
North Carolina ◽  
Combining Ability ◽  
Recurrent Selection ◽  
General Combining Ability ◽  
Moniliophthora Perniciosa ◽  
Disease Symptoms ◽  
The North ◽  
Parent Selection ◽  
Selection For ◽  
Different Origins

The objective of this work was to identify genotypes with high general combining ability for resistance to witches'-broom (Moniliophthora perniciosa) in populations formed from a first cycle of recurrent selection. Highly productive and resistant clones from different origins were interbred using the North Carolina II design. The clones SCA 6, CSUL 7, RB 39, CEPEC 89, OC 67, BE 4, EEG 29 and ICS 98 were used as paternal parents, while the maternal ones were NA 33, CCN 10, IMC 67, P 4B, CCN 51, CEPEC 86, SGU 54 and ICS 9. Twenty days after germination, 56 seedlings of each cross (four replicates of 14 seedlings) received the inoculation of a 1-mL suspension with 7.5x10(4 ) basidiospores mL-1. Symptoms were evaluated 60 days after inoculation. Significant differences were observed among paternal and among maternal parents, for resistance to witches'-broom assessed according to the proportion of progeny seedlings with the disease symptoms. Differences were also observed between groups of mothers or fathers previously defined as resistant, and groups previously defined as susceptible. It is possible to obtain a combination of genes that can increase the level of resistance to witches'-broom directly from the first cycle of recurrent selection.

scholarly journals Diallelic analysis for lysine and oil contents in maize grains

2009 ◽  
Vol 66 (2) ◽  
pp. 204-209 ◽  
Author(s):  
Leonardo Oliveira Medici ◽  
Salete Aparecida Gaziola ◽  
Vanderlei Aparecido Varisi ◽  
José Antonio Carmezini de Paula ◽  
Renato Rodrigues Ferreira ◽  
...  
Keyword(s):  
Grain Yield ◽  
Combining Ability ◽  
Oil Content ◽  
General Combining Ability ◽  
Lysine Content ◽  
Nitrogen Levels ◽  
N Level ◽  
Complete Series ◽  
Selection For ◽  
Selection Of

Six S5 lines of maize, with differences for lysine and oil contents in grains, were used to carry out a complete series of diallelic crosses. The resulting 15 hybrids were grown in a field at two nitrogen levels (10 and 130 kg N ha-1). The general combining ability (GCA) and specific combining ability (SCA) were obtained by using the method 4, model I of Griffing for grain yield, and grain lysine and oil contents. Significant (p < 0.001) interaction was observed between GCA and N levels for grain yield, indicating the selection of different lines for each N level. This interaction was not significant for lysine content, but there were significant effects of GCA for this trait at both N levels (p < 0.1). Significant effects were not observed for GCA or SCA for oil content, however a positive correlation was observed between lysine and oil contents in the hybrids, in the lines and even in the control cultivars. The results indicate the effectiveness of selection for lysine content, irrespective of N level, in the studied non-opaque maize lines, and the possibility of achieving both high lysine and oil content in grains.

EFFICACY OF EARLY SELECTION FOR FIRE BLIGHT RESISTANCE AND THE ANALYSIS OF COMBINING ABILITY FOR FIRE BLIGHT RESISTANCE IN SEVERAL PEAR PROGENIES

1990 ◽  
Vol 70 (3) ◽  
pp. 905-913 ◽  
Author(s):  
H. A. QUAMME ◽  
F. KAPPEL ◽  
J. W. HALL
Keyword(s):  
Combining Ability ◽  
Fire Blight ◽  
General Combining Ability ◽  
Specific Combining Ability ◽  
Maximum Likelihood Estimates ◽  
Blight Resistance ◽  
Stages Of Growth ◽  
Greenhouse Test ◽  
Selection For ◽  
Made In

A set of progenies was tested for fire blight resistance by needle inoculation at 3 mo of age in the greenhouse and then 5 yr later in the orchard to determine if the measurements of fire blight resistance made in the greenhouse was correlated with those made in the field. The correlation of fire blight resistance at the two stages of growth was weak or absent on a single plant basis. This indicated a lack of precision in the greenhouse test but genetic gain based on the field measurements appeared to be possible if plants were selected in the greenhouse with less than 19% of blighted shoot length. In another set of progenies, the greenhouse test was observed to delay fruiting, but the delay was not greater than 1 yr. It is proposed that selection for fire blight be carried out at both stages of growth, in the greenhouse as single measurements on young plants and again in the field when repeated measurements can be made. Maximum likelihood estimates of the variance components determined on data that were transformed by arc sine of the square root and corrected for censoring more than 100% blighted shoot indicated a high general combining ability and a low specific combining ability for fire blight resistance. Genetic variance was, therefore, predominantly additive. Combining ability estimate indicated Kieffer was the superior female parent and HW 601 and Old Home were the superior male parents. If this sample of parents is representative, genetic advance for fire blight resistance should be obtained by selecting parents on the basis of phenotypic values.Key words: Pyrus, Erwinia amylovora, general combining ability, specific combining ability

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