I was looking into the literature surrounding the "runt" hypothesis that Roy has put forward. For reference he also is generally referencing looking through mericloned seedlings to find the polyploids arising from this cloning technique (in the context of his personal anecdote). This allows you to find one "type" of tetraploid as there is multiple mechanisms that result in a duplication of chromosomes. There is documentation that colchicine induced tetraploids in some plant types results in dwarfism and these plants have some disregulation with plant hormones because the doubling of the chromosome increases the amount of a regulatory mRNA which disrupts the signaling pathway. Additionally, runts may also be >4n which also results in other types of regulation of growth, so that precious tetraploid you think you have could just be a crazy chromosome mutant that will be cruddy its whole life.
Which is to say, all polyploids are not created equal and you are better off culling any weak plants, plants that lack characteristics of vigor, ect. than hoping for a rare tetraploid, which may or may not have anything good about it. This is why breeders have moved to oryzalin and colchicine treatment of protocorms because you can generate a lot of tetraploids with select plants and then select the best ones. This results in significantly more "useful" plants compared to the old needle and the haystack approach.
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