Twenty B3 lines (families) eliminates most inbreeding after intercrossing, enhancing the chance that a population will not collapse.
Effect of Partial Diallel Size on Inbreeding
Chapters add genetic diversity
The effect of adding sets of 20 B3-F2 progeny from our chapters on inbreeding effective population size, for one source of blight resistance. Restoration ecologists estimate that effective population size needs to be 50 to avoid immediate collapse from inbreeding depression and 500 for mutation to offset long-term erosion of genetic diversity by drift.  Chapters also add adaptation to their local environment in addition to general genetic diversity.
248
0.0060
5
214
0.0070
4
176
0.0085
3
130
0.0115
2
72
0.0207
1
Inbreeding Effective Population Size
Inbreeding Coefficient
Number of Chapters