Natural cross-pollination and the identification of hybrids between botanical varieties of Brassica oleracea L.

Summary Five botanical varieties of Brassica oleracea were grown in isolated groups of three plants. The sets of three varieties were chosen in such a way that the male parents of single plant progenies could be identified. Identification of hybrids and selfs in the progenies proved to be easy and accurate.The mean levels of cross-pollination were: sprouting broccoli 95%, kohl-rabi 91%, kale 83%, cabbage 73% and Brussels sprout 72%. There was little relationship between the self-compatibility of plants and their degree of cross-fertilisation as any natural tendency towards self-pollination appeared to be swamped by the presence of abundant foreign pollen.