Well, start by thoroughly researching chimeras & sports. Chimeras are common in the plant world. They occur when a cell undergoes some sort of mutation. The mutation may be spontaneous or it may be induced by an extraneous source, like irradiation or treatment with chemical mutagens. If the mutant cell is is found near what's called the crest of the apical dome, then all other cells which occur through division of that cell will be duplicates of the mutated cell. When this phenomenon occurs, there will be cells of 2 different genotypes growing side by side in a plant tissue - or a chimera. If the mutation occurs in a plant area where the likelihood of extensive further cell division is unlikely, then the probability of even detecting or noticing the mutation by cursory inspection of the plant as a whole is low.

Technically speaking, a sport is a plant or plant part come into being as the result of some mutation, chimeral rearrangement, or recombination that is usually genotypically different from the original plant. Chimeras are probably best described as sports (usually naturally occurring chimeral rearrangements) that have been vegetatively reproduced.

Al

Wow! Chimeras! This is reaching back into my college botany days, so bear with me.
The two most common ways of producing mutations (chimeras) in plants are by radiation and by the application of chemicals called mutagens. There are hundreds of these chemicals, but perhaps the one most commonly used in college classes is an alkyloid called colchicine. The names of some others can be found on the internet, or in any good college biology or botany text book. However, acquiring the chemicals themselves may prove to be more difficult, for obvious reasons.
The chances of creating a worthwhile mutation, and one that can be reproduced, is not very good; many of these mutations are actually fatal ends in themselves. Since these are not controlled chromosomal changes, they are really a mathematical crap shoot
Colchicine is sometimes used as a medicine to control inflammation, so it might be available, but I don't really know. I would urge extreme caution, and would suggest this type of thing is best done in a tightly controlled and well equipped laboratory.....Elder (Lou)

Thanks for the replies people. I have done some reading.

One method would entail making two precisely identical cut scions ready for bark grafting. One of species "a" and the other of species "b" of which the chimera is to be made. Then each prepared scion would be split lengthwise down the middle through the bud with a very sharp thin, instrument such as a razor blade. From these, two bark grafts could be made, one a + b the other b + a. These are then brought together so the bud halves are perfectly aligned and inserted as bark grafts. If one is extremely lucky, and the bud halves don't die and they heal together and grow you could get a chimera.

Apparently, a grad student at the University of MD tried to obtain graft induced chimeras in the early 90's by using in vitro techniques. She was trying to produce a "hand in glove" type apple chimera which would have the outer cell layer from a scab resistant apple variety and the inner cell layers from a high quality apple susceptible to scab.

Was the grad student successful? It's an interesting concept, designer chimeras with no mutation. Zoologists have created animal chimeras using eggs of closely related species. I know they have done it with goats and sheep, but don't know any of the details, or eventual outcomes. Hey, when I was studying biology they hadn't yet discovered DNA!!!
By the way, most of what I said in my first post refers to the mutation. Once the requirements spelled out by Al are met, then vegetative reproduction is almost always successful....Elder (Lou)

Elder, that was all I could dredge up on the grad student. I find it interesting however. I suppose if they were successful, we might be seeing the results of it by now, so maybe it wasnt too successful.

I do like the idea of grafting two scions together cut sagitally down the buds. Low tech has always been a kind of forte' with me!

I think to pull it off, one would first wrap the composite scion with parafilm to bring the halves closely together and seal in the moisture. Then carefully make the required grafting cuts and treat as normal.

I would appreciate any and all suggestions that would help in such an undertaking. Like maybe use something stronger than parafilm to bring the halves together.

Diameter of scions should be pretty much identical. Placement and shape of buds should also be close to identical. Not to mention the cutting technique. I am sure that should go without a hitch as well.

If I find some time to try this, I will post to this forum.