See link below.
Thank you Henry for posting this article. It was fun to gloss through it!
I was mainly interested in the parts about somatic embryos which have blunted radicles and do not want to root. This interests me, as I have noticed the same thing occur from time to time with a percentage of seed-derived mature rose embryos (irrespective of how I have tried to culture them so far).
I wonder what causes this to happen, and what remedies, if any, could be used in a simple “back yard / low-tech” operation.
Don, if you are reading this, I would love to also hear your views on this problem?
I have wondered whether visible sunlight (as well as UV radiation), might induce an inhibition in initiation of rooting out of the radicle, causing some embryos that are susceptible to this, to have this “radicle blunting”.
I guess one way to test this idea would be to try to germinate embryos in darkness, and see if there are any cases of “radicle blunting”.