Baby Tuberising TPS

Finally got some time yesterday to look at the seed tray my TPS were sown in, back on 3rd of March. About a week or 10 days after sowing,  I pricked out tiny seedlings from half the tray, about 20 or so, some into square tomato seedling pots, and some into some disposable cell trays. They were planted deep, only half filling the pot, leaving space to 'hill up' the plants, which is supposed to encourage tuberising.  This is important - to get these little plants through the winter is probably going to be a bit of a struggle, even in the greenhouse. The tubers can be stored until next spring, when i can plant them into the garden. It will also allow me to assess colours and form to some exent, prior to growout.
A quick look over the tray didn't reveal any stand out foliage differences - I was thinking that 'Pinkeye' might not have much diversity in the line. A more considered inspection did reveal differences in stem colour - some were green, some with a tinge of red at the base, and others with more substantial colouring up the stem.
The stem colour was not really apparent in the early ones I had pricked out. I haven't done a count, but it looks like the early germinators are mostly pale stemed. This might just be coincidence.

I was a bit surprised when i started excavating the seedling tray to find the plants tuberising. Some reports on potato forums suggest this can be a bit difficult to initiate. I was even more chuffed to find one tuber with colour.

Another point of interest was that some plants were stolonising - sending out above ground runners. Not having grown TPS seedlings before, I don't know if this is usual or not.

 Interestingly, the potted up seedlings seem not to have developed tubers. I only unpotted one plant to look, but couldn't see any tuberisation. Things are looking good for next spring.