Comparative analysis of pyrethrin content improvement by mass selection, family selection and polycross in pyrethrum [Tanacetum cinerariifolium (Trevir.) Sch.Bip.] populations

• Mass selection raised pyrethrin content from 1.37% to 1.69% in progeny population.
• Pyrethrin content of progeny population improved even more to 1.87% by polycross.
• Family selection did not improve pyrethrin content.
• Mass selection and polycross increased the frequency of desirable individuals in populations.
• Polycross is more effective for the rapid improvement of pyrethrum populations.

Pyrethrum [Tanacetum cinerariifolium (Trevir.) Sch.Bip.] is a well-known plant widely used for the production of natural pyrethrin insecticides. One of the main breeding goals is to increase pyrethrin content. Comparative analysis of three breeding methods for the improvement of pyrethrin content by mass selection, family selection and polycross was carried out based on an unselected heterogeneous population. Twenty-three elite plants were identified in the base population, and one round of mass selection raised the average pyrethrin content from 1.37% to 1.69% in the progeny population. Polycross was conducted using 23 clones derived from the above same 23 elite plants derived from the base population, and the average pyrethrin content of that population improved even more to 1.87%. As a third method 12 out of 23 families were selected and hybridized within each family. This method did not improve pyrethrin content. Both mass selection and polycross increased the frequency of desirable individuals in the improved populations, and the variation coefficient of pyrethrin content was reduced from 29% in the base population to 18% and 16% after mass selection and polycross, respectively. These results show that polycross is more effective than mass selection for the rapid improvement of pyrethrum populations, and that family selection is not suitable.