If I have a liquid culture of developing embryos, which will include haploid, doubled-haploid (diploid) and a small amount of tetraploids, I'd ideally like to do something to kill off all the non diploids, or if that is not possible, develop a method to select out only the diploid plants, once the embryos have grown to the torpedo stage (around 2-3 mm in size). A stain which would produce a visible difference would be best.