RA 00110.pdf - OAR@ICRISAT

Table 4b. Prediction equations, advantages, and disadvantages for intrapopulation improvement using half-sib selection.
Half-sib 1
Selection of selfed males based upon progeny tests
Advantages
Disadvantages
1.
2.
3.
1.
2.
3.
4.
Progeny tests can be as extensive as desired.
Good flexibility of the system because of choice among several types of testers.
Each selfed male is a potential new inbred line.
Takes three growing seasons.
Can be relatively costly, as in any system with yield trials.
Effective population size may be small.
Rate of gain may depend upon tester chosen.
Half-sib 2
Selection and recombinatiion of the half-sibs themselves.
Advantages
Disadvantages
1.
2.
3.
4.
1.
2.
Can test extensively because there is ample seed.
Less costly and easy to do.
Takes two growing seasons.
Can maintain large effective Ne.
Costly yield trials.
Do not have a start toward inbred line development.
Half-sib 3
Modified ear-to-row, 1 generation/cycle.
Advantages
Disadvantages
1.
2.
1.
2.
3.
1 season cycle length.
Can maintain large Ne.
Costly yield trials and detasselling labor.
Do not have a start toward inbred line development.
Large isolation needed.
Half-sib 4
Modified ear-to-row, 2 generations/cycle.
Advantages
Disadvantages
1.
2.
3.
4.
1.
2.
Smaller isolation than in 1 yr/cycle scheme.
Less costly in labor.
Can still maintain large Ne.
Yield trials only in alternative seasons so less costly.
Do not have a start toward inbred line development.
Gain per year slightly reduced over 1 generation/cycle scheme if one only grows 1 generation per year.
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