http://www.biology-online.org/biology-forum/about10736.html
Plants either osmotically absorb things or actively pump them using transporters - the second is more important if the thing being transported is already at a higher concentration in the cells than it is outside (since nothing goes uphill without being pushed).
One guy in this thread mentions that there are active sucrose transporters in the root. That may be true, but I know there are active transporters on the vacuoles within the cells and he may be thinking of those.
In osmosis, you have pores in the cell membrane that are the right size for the molecules to drift through. The cells will open and close them, or use energy to pump things through them. Most of those are for tiny things like water or salts. Sucrose is a big molecule compared to them.
If the plant took up sucrose by drift osmosis, for most plants that'd mean they lost sucrose to the soil with it leaking out the roots. If they actively take it up, that'd mean spending sucrose to get sucrose? And probably spending more than you're getting.
There are only two possibilities I can think of.
The cells pack sucrose into the vacuoles, allowing it to drift diffuse into the cells from the soil (but it's probably also be doing the same thing out of the phloem as well).
Or, the plant spends nutrients it has in abundance to actively pump sucrose in - that also sounds a bit suspect. Plants generally never do anything they don't need to, like taking up one nutrient on the off chance it might to use it to pump some sucrose later - while that nutrient is sitting inside the plant at higher than needed concentrations, it'll probably need energy to get it there or be interfering with other cell processes.
I've done quite a lot of biology about plants at degree level and never heard anything about sucrose uptake.
The only way this is getting proven for sure is with a bunch of separate side by sides.