Studies on the induction of polyploid flower plants and their utilization. IX

Abstract

Since 1954 several original autotetraploid plants of deep-red Calabrian Soapwort, golden yellow Common California Poppy, slightly-double flowering late Cosmos and Rose Campion were produced by treating with the colchicine solution to the germinating seeds or the growing points of seedlings. The tetraploid progenies (2n=56) of Calabrian Soapwort grow more vigorously with distinctly enlarged flowerlets, thickened leaves and dickered stems, but somewhat later flowering and producing a quantity of larger seeds than the original diploids in the greenhouse. So it is expected they will surely become a new decorative strain in future. Although the tetraploids (2n=24) of Common California Poppy reveal a peculiar attractive form of enlarged flowers with wider petals as well as the description of Dalbro (1950), they hardly produce any seeds in the present growing place. Such an occurrence seems to be a typical example of showing characteristics of the general induced autotetraploids which are very unstable for the genetical constitutions and are easily affected by the environmental conditions for growing and seed production. The tetraploid Cosmos plants (2n=48), however, have almost the same sized flowers as those of diploids, even if their stems are so stiffer and leaves are longer and thickened enough. And the main characters of the tetraploid Rose Campion (n=48) are not yet unknown but for the distinctly thickened leaves, owing to unbolting in summer of 1956 caused by their slowly growing perennial habit.