Thought I would share an interesting observation of mine - one of our Yuzu seedlings formed a blossom with male and female parts (though the female may have been a little underdeveloped), making it precocious! However I have read that these precocious seedlings don't often form flowers again after the first year until maturity.
It is probably only 1-2 months old but it had a very weak root system that was rotting in equal conditions to our other Yuzu seedlings so I micro-grafted it onto a healthier root system. I have also done this with Thomasville seedlings and a unifoliate US-852 seedling. All the grafts have taken nicely!