Fig. 1

Model-based subdivision of population structure. ‘a’ presents the estimation of the Ln (probability of data). Delta K was calculated from K = 2 to K = 9. ‘b’ presents the population structure of the 1,857 maize accessions deduced by membership coefficients (Q values). Each horizontal bar presents one accession, which is consisted of K colored segments. ‘SS’ is the abbreviation of Stiff Stalk Synthetic group, “MICN” Modified Introduction of China, ‘TS’ Tropical/Subtropical group, and NSS Non-Stiff Stalk