Developing tubers on the TPS seedlings

Yesterday I potted on some of the TPS seedlings from the cell trays. The cells are about 3 cm cubes, and the plants were getting 10 - 15 centimetres high. I was surprised at the size of the tubers that were developing in such a relatively small amount of soil. The seeds were sown on 3 March, so about two months ago.

Without really poking into the plants I couldn't really determine what the tubers were like, but one had enough showing to indicate that it had a purple end.

Most of the others from what I could see were just straight white spuds. Hoping I can get some of the tubers to grow a bit bigger. Looking good for next season.