Curious about this thread ...
How is the taste and why some have fruits and others not ?

My one year old graft of prague citsuma (near Bordeaux, SW France).

Great !

You must have green HANDS !

Oh, there are 2 leafes on the left side, who try to be trifoliat .. looks funny !
Maybe it is even a bud sport mutation ...

No. Citsuma Prague tends to have bi- and trifoliate leaves. New vigorous growth bears often trifoliate foliage.
/Robert

Aha !

Still funny to have different leafes on some branches ...

It is quiet normal, also my thomasville citrangequat has same kind of leaves.

ok

Here they are not variegated, are they ... ???

Sanguinello, you don't understand anything. Prague chimeras are not variegated.
Because as I tried several times to explain to you, you need an albinos cells lineage to be part of the chimera to make a variegated plant.
But as you don't want to listen, you will not hear.

... at least I can read what you wrote :

These photos are all Prague "hybrids".
I have two in ground one turned variegated the other not. One is a graft of the other. They are the same variety.
The variegation is only visible in November and December.

OK
I shall try a last time.
1) Chimeras are made of two different lineages of cells.
2) if both lineages are green the plant is green.
3) if one of the lineage is albinos the plant is variegated.

If my theory is right:
1) Prague plants are chimeras of two green plants (PT and Satsuma).
2) therefore Prague plants are green.
3) at a certain time of the year and in certain conditions the cells of one of the lineages get clearer. (I presume Poncirus).
4) that makes the typical pattern of the variegation appear on the leaves.
5) but this is not variegation because when the conditions return to normal the leaves revert to green.

I think this way it is very easy to understand (we could say "biology for morons" or "idiotproof lecture") but I bet you will not.

well, sure it is idiot proof to call it one time Variegation and then not ...

Sylvain that makes sense. In the fall poncirus changes color and drops it's leaves. If it is a true chimera that would be very interesting.