Grafting Kumquats to Incompatible sour orange rootstock

Sour orange rootstock produced the best tasting citrus trees of almost any variety.  Kumquat are incompatible with sour orange and die quickly if they even start growing.  I am grafting a poncirus trifoliata to sour orange roots and will later graft my kumquats to the poncirus trifoliata using the PT as a bridge between two incompatible trees. Below Are fresh grafts then the grafts unwrapped.  Last years PT grafted to sour orange  and last a Fukushu kumquat grafted to PT rootstock.

The Poncirus Trifoliata grafted to Seville sour orange has produced many trunks of which 2 are big enough to T-Bud graft a fukushu kumquat onto.  The Seville sour grows more vigorously and larger than the Poncirus trifoliata.  The growing of 2 trunks of Poncirus will balance out the Seville's faster growth.  The Poncirus and Fukushu trees' growth rates match each other closely.  The combination of all 3 should result in a balanced tree.  Once the Fukushu buds grow the tops of the Poncirus Trifoliata will be trimmed so the Fukushu become the fruiting tree.
T-Budding thread with pictures show step by step how to graft'
 https://permies.com/t/148795/Budding-citrus-trees-Seville-sour

Both Fukushu bud grafted buds are now growing.  I Have broken the stems above the grafted buds over to encourage the tree to push its new buds.Once the new growth has enough leaves to support the entire tree's food needs I will remove the original Flying dragon rootstock growth above the new grafts.

At this time it is probably safe to say that the grafts are successful.

There is enough growth on both of my new Fukushu kumquat shoots to cut all of my non kumquat twigs.  This leaves me with 2 clearly visible Fukushu kumquat trunks with leaves.

The 2 shoots have finished growing.  I will give the tree plenty of light but will not feed it until mid march.  It will be time for the tree to start growing and I can acclimate the tree to sunlight at the same time.
https://youtu.be/U9Ai8FvadQ0

Thank you for sharing this info but how did you find the information that told you what would or wouldn't graft?

I've a lime, nasty thorns n all. Can't kill it thankfully because I'm on my 4th meyer lemon, second kumquat.
Wanted to graft onto the lime since it surives all my abuses. I don't know where to find the information needed to know if that will work.

We are contemplating a big move, I could maybe take one tree so if I could graft onto the lime.

One more question,  what are the bucket lights for, could you explain a bit about them.

The bucket lights keep in humidity from plant and warmth from the light bulb.  The white buckets shine white so that the leaves that are shaded get light from the buckets walls.  It is warmer, more humid, and much brighter inside that 3 bulbs without the bucket.  Think mini personal grow tent.
https://crec.ifas.ufl.edu/extension/citrus_rootstock/rootstock-literature/1998%20Ferguson&Dasle,%20FSHS.%20Kumquat%20Calamondin%20Compatibility.pdf
I don't remember where I read 8 years ago that kumquats are incompatible to sour orange.  Meiwa kumquat trees are very hard to graft.  They grow well from seed.
The bucket light picture above is named inaccurately and is supposed to read.

Update on my Fukushu kumquats.  I plan an keeping these in containers.  The Fukushu grafted to the sour orange with the Poncirus Trifoliats stem separating the incompatible Fukushu to sour orange.  grew very well.

An update on new growth

Update on Fukushu kumquat tree on sour orange.  The smaller trunk has a second branch come out of it.

Its been about a year since the last post.  It is flowering now but is too young to hold onto fruit.
https://www.youtube.com/watch?v=3FSi2t83aPE.
The grafts all look good so far.  The grafting of Poncirus trifoliata to Seville sour orange would normally never be done so there is no data on compatibility between them.