I started three cacao seeds that were passed on to me from a cacao tree in the San Francisco Conservatory of Flowers. The first seedling was the control and potted only with Fox Farm's Ocean soil, the second seedling also with this soil, but I added beneficial mycorrhizae in powder form. The last seedling received and will continue to be fed "Native Nutrients 100% Mushroom Compost" alongside it's Fox Farm Ocean mix. All 3 plants will be kept on an East facing window with morning light exposure at around 50/50 light to shade until about 11a and then on until sundown they will have bright shade. Indoor temperatures average around 72 degrees (f) with between 62-78% humidity in it's placement within the kitchen. With cacao plants growing so well under shade it is quite obvious that their relationship with beneficial bacteria and fungi is essential for it's basic survival and growth.

There are only a two variables that can interfere with results like depth of the pots (not likely, but easily visible if it becomes a factor) and the fact that one of the cacao seedlings (in mushroom compost mix) after removing its dried out, outer brown skin looks to be a pale green bean versus the reddish brown undercover pigmentation of the other two beans.
We shall see. I've read, "The Chocolate Tree - A Natural History of Cacao" by Allen M. Young and if you're interested in chocolate like I am then you should at least read this through once along with "The Chocolate Tree: A Natural History of Cacao" (Smithsonian Nature Books), which seems to be a different book by the same author.

Control Bean "A"

Bean "B" w/ Mushroom compost

Bean "B" picture 2

Bean "C" w/ Mycorrhizae

Bean "C" picture 2

Control Bean "A" picture 2