Mine appear to have their cotyledon grow, green, thicken and then dry out (though I can’t be sure) while the radicle turns brown. Some have brown edges on the cotyledon. I wonder if the heat from the sun does this? They are taped on the window
The first ones it happened to, I planted them in soil to see if that’d help. Still awaiting results
Not unusal. It’s possible you nicked the radicals when removing the testae or the tip of the radicals just popped off and stayed with the testae but its also possible that there was a genetic problem preventing the roots from developing. I often see roots fail to develop in a way that resembles the first one. It usually affects many embryos of the same cross and I have termed it the ‘blind root’ trait.
No way to overcome this problem except with sheer numbers (and more careful dissection in some cases).
I wonder if the heat from the sun does this? They are taped on the window
Not in this case. Heat damage causes the cotyledons to turn brown or sometimes the color of cooked greenbeans where they lose the brightness of the chlorophyll due to conformation deformation that causes the central magnesium ion to pop out of place.
Apple embryos are typically larger than rose embryos so need more soaking to leach abscissic acid out of them. Where you see only one cotyledon turn green it is usually the one in contact with the wetted towel because abscissic acid could continue to diffuse into the towel.
I would not complain about even a single embryo out of five (or 10, or 20) germinating. There is so much genetic misalignment in rose hybrids that we are lucky when a cross works at all. The wider the cross the less likely it is to succeed.
