Cross vs Reverse Cross

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kal9988
Posts: 69
Joined: Wed Nov 04, 2015 1:18 am
Location: Los Angeles, CA

Cross vs Reverse Cross

Post by kal9988 »

How different are hybrid plants likely to be when you cross two plants together? Like if you pollinate plant A as the mother and B as the father, and then do the reverse, how likely are the two groups of seedlings to be similar or different from each other?
george76904
Posts: 487
Joined: Thu Jan 15, 2015 2:01 am
Location: Americus GA

Re: Cross vs Reverse Cross

Post by george76904 »

Listen to the others I was wrong :oops: my bad.
Last edited by george76904 on Wed Dec 23, 2015 4:23 pm, edited 1 time in total.
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
Location: Nottingham, England/UK

Re: Cross vs Reverse Cross

Post by DaveW »

Very different probably, and not only each group but each seedling will be genetically different from the others even if they initially look like the parent due to recessive genes. To be able to produce predictable F1 hybrids as you get in commercially bought flower and vegetable seeds this is evidently what the commercial seed firms do:-

"For mass-production of F1 hybrids with uniform phenotype, the parent plants must have predictable genetic effects on the offspring. Inbreeding and selection for uniformity for multiple generations ensures that the parent lines are almost homozygous. The divergence between the (two) parent lines promotes improved growth and yield characteristics in offspring through the phenomenon of heterosis ("hybrid vigour" or "combining ability").

Two populations of breeding stock with desired characteristics are subjected to inbreeding until the homozygosity of the population exceeds a certain level, usually 90% or more. Typically this requires more than ten generations."

Amateur hybridisation of plants on a small scale is very hit and miss and it always makes me laugh when I see seed being offered of named hybrids by cactus seedsmen with the buyer expecting to obtain the named variety from it, since I am sure the seedsmen have not to gone to the above 10 generation trouble. The only safe way to propagate a named hybrid is through vegetative propagation since that cultivar name only attaches to that one original seedling. Even the same cross again will not produce genetically identical plants and should receive a new cultivar name.

Also to get anything worth keeping remember people like rose breeders raise seedlings by the thousands to flowering size then throw most of them away, only keeping the odd one that may result in something worthwhile or be used for recrossing again.

All the Hibotan grafted cactus "Red Lollypops" you see are vegatatively produced from the one original seedling.
iann
Posts: 17184
Joined: Mon Jul 24, 2006 11:10 pm
Location: England

Re: Cross vs Reverse Cross

Post by iann »

These two pots of Lithops are from crosses between the same two parents. One parent was L. otzeniana 'Aquamarine' and one was L. otzeniana 'Czesky Granat'. Neither cross has come true to either parent, although there is a single quite good 'Czesky Granat', perhaps from a selfed seed. Most interesting, as a whole they are quite different, one favouring the green parent more strongly and one just generally muddy.
otzeniana-0113.jpg
otzeniana-0113.jpg (81.25 KiB) Viewed 730 times
--ian
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