Don't know about mango, but I always wondered about grafting on to a inverted bark graft to promote flowers
basically graft onto a tree , and take a piece of bark on that tree and graft it back on , but upside down .
Supposed to prevent the flow of sugars, and force the tree to flower earlier or something like that.
Why do you ask trying to breed or just want fruit fast?
With other trees if your looking to breed them super fast,
and do not care for fruit yield but want flowers for the pollen could restrict the roots in pots just to get pollen to breed with.
I do not know about mango, but Saw a persimmon flower first year in pots in nursery, and hold fruit, but doesn't always happen.
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