Quote:
Originally Posted by bower
hi tpeltan, welcome to T'ville. 
Actually I saw your post in my inbox before you deleted it - and it made perfect sense. If you backcross to one of the parents, or to a sibling in the same line, you're still moving towards stability. indeed, more homozygous genes is bound to result. 
It does get a little tricky to reckon, just when will it be completely stable.  maybe seven generations is a good bet, whether you backcross or not. At least for us amateurs.  |
Hello and thanks for welcome.
I read the previous part of thread in wrong direction and if I understand it now correctly they intend to backcross to unstable line. Then my post made little sense (despite being correct for stable lines).
The original post:
This is not true. If you backcross (to stable (OP)) variety = homozygous genotype, you increase the share of this variety. If you backcross the F1 to one of parents, the result will have half genes homozygous (equal to parent) and half heterozygous. This is comparable to F2 (where half remains heterozygous, half homozygous (quarter and quarter equal to each parent).
e.g.
BC1: F1 x P = Aa x aa = Aa + aa
BC2: BC1 x P = (Aa + aa) x aa = Aa + 3 aa
If you practice backcrossing long enough, you result with the parent you backcross to (and hence stable).