(I was reading about Marula, and this post came up, in the search engine. I see that it's old.)
Mine are germinating under temperatures, which were uncommon, for us. The thermometer on the always-shady, North side of the house read 114F and led to a freak hail storm. (August, 2")
5g pot, filled with 50% loam and 50% leaf mold, well draining, consistently moist, no pre-treatment or cold stratification.
In my quirky, not-always-scientific point of view, mushrooms and sprouts seem to pop up, naturally, under low-pressure systems. It may be impractical to recreate this, experimentally, but the warmth can be provided somewhat more simply.