There was a concept of 'node count' promulgated on the old Gardenweb and Forumup forums that basically stated that a grafted scion/budwood, or a cutting, 'remembers' its maturity and will express sexual maturity depending on this node count. It's my understanding that a 'node' is essentially equivalent to a growth flush. Seems reasonable, but I think there's more going on.
It's clear that grafted citrus and branch cuttings flower sooner than their seedling brethren that are focused on vertical growth to capture sunlight and root growth to ensure survival. However:
(1) A farmer near me has an old seedling lime tree that was broken off near the soil line during a cyclone two years ago. The root suckers are now blooming in abundance. The root suckers should have a single digit node count, yet mature at 24 months.
(2) There is evidence that flowering can be accelerated by grafting a young seedling scion onto a mature tree, so the mature tree pushes the scion a lot. Thus it seems flowering is also influenced by the rootstock.
(3) I've had some 10 month old rough lemon seedlings bloom after being stressed to near death with lack of water, while the better-cared for seedlings did not.
Is it really node count, or is flowering a much more complex event?