Carrot root means the roots are a piece of shit right now. They look like a carrot having no fibrous roots. Nursing them back so that they might have fibrous roots again is the name of the game.
I put everything on northern pecan seedlings I purchase from Missouri's DNR. Northern pecan seedlings are cold-hardy thru zone 4a and will grow thru zone 8 I'm sure without a hiccup. Every now and then I have my own seedlings of Hark and I'll graft onto F2 Hark. It's nursery practice to graft hickory, hican, to pecan. A growing season on pecan roots is longer than on hickory roots and the hickory/hican nut will mature it's nut (kernels) and be larger overall.
The requirements of anything within the Genus Carya is pollen exchange when the pistillates are receptive and when the staminites are shedding. Therefore a hican could be pollinated from a pecan or hickory or any combination therof. The problem with this however is that hicans shed pollen when the vast majority of pecans are not shedding or receptive and vice versa. The best bet is hican along with other hicans or hickories with other hickories and pecans with pecans. Still, you need to know pollen shed dates and whether a tree is receptive first or shedding first. If you don't know what I'm saying look up the terms proandrous and protogynous.
I have other hicans and hickories, too. I was looking at them, yesterday. There are some in single #'s that I'll want to plant for stock plants though. I'll have a complete list ready next year. Those with carrot roots being in the same containers will require that I tug on them to see if they'll come out too easy (will need another year if the case) of if they rooted in enough to be sellable.
Hope this helps.