There is no mention of Tabaluga's mother at any point of the cartoon, although it is confirmed in season 1 that there are female dragons. However, in season 3 second-to-last episode, when Tabaluga goes to Dragon World, he meets a dragon family that looks normal... until we realize that the baby, Sparky, is the only one from said world to have green skin (all other dragons are brown-ish, grey), and the second dragon in the whole series to be green... after Tabaluga.
There is a possibility of this not being a plot hole if we take a look into genetics: during the early development of a fetus, there is extremely rare chance that recessive genotype will mutate and turn into dominant one. Since none of Sparky's parents are green like their son, he's the proof that such mutation happened in him - in case of skin color.
Since all dragons from Greenland except Tabaluga were not green (The Flow of Time shows Tyrion's parents who are light grey), Tyrion's genes can be eliminated as the source for this mutation - it was DNA from mother which mutated and turned the skin green. Since the only known example of such mutation is Sparky - then his mother is also Tabaluga's mother, because Tyrion also received Dragon Pendant, which requires getting to the Dragon World. Comparing their season 3 appearances, their age difference was probably not that big.
The conclusion? Tyrion wasn't so good as the previous 76 episodes described him, and Tabaluga probably was not planned at all - bonus argument for that being that only Nessajja and Shouhu knew about Tabaluga's identity. This also makes Arktos' downfall in the series finale hilarious - it simply wouldn't happen if Tyrion would not fall in love.
