Preliminary Study On The Heterotic Relationship Between Temperate And Tropical And Subtropical Maize Populations

The narrower genetic background is the first constraint restricting the maize (Zea mays L.) breeding efforts in China. The approach to solve this problem is to enhance and improve the germplasm, based on heterotic groups and patterns. Genetic diversity research has been conducted for inbred lines, but not yet for OPVs, populations and synthetics with broader genetic background. Design II was adopted to cross 4 common testers with 14 tropical, subtropical populations from CJJVIMYT, and 13 domestic temperate populations. The 108 testcrosses were evaluated under an a-Lattice design in 4 locations in 2 years. The 27 populations were evaluated based on GCA and SCA effects, and then try to classify the 27 populations into 4 groups. The main results are summarized as follows:(1) The GCA effects of the tropical and subtropical populations were generally higher than that of domestics. Stay Green, Pob501, Pob502, Pob21, Pob43, Pob32, and Suwanl from CMMYT, and domestic germplasm WBM-C4, CSyn 5, Yuzong 5, CSyn3, CSyn4, Jizong A were highly potential in yield.(2) Pob45, PobSOl, Pob49, Stay Green from CIMMYT performed lower SCA with PA group, and Pob28, Pob46, Pob21, Suwanl, Pob43 were closer to Sipingtou group at the background of heterotic pattern (Ye478 x Huangzao4) in the Summer Maize Area in the Yellow, Huai, and Hai rivers valley. Domestic populations Yuzong 5, Csyn4, Dongnong C5, Csyn3, Liaolv, Jizong A were classified into PA group, CSyn5, WBM-C4, Shanzong 1, Shanzong 3, Golden Queen were classified into Sipingtou group.(3) At the background of heterotic pattern (Dan340xMo17) used in spring maize area in North China, Pob45, Pob43, PobSOl, Pob46, Stay Green, Pob28 performed lower SCA with Ludah Red Cob group, and Pob49, Pob21, Suwanl were closer to Lancaster group. Among 13 domestic populations, Golden Queen, Csyn4, Csyn5, Liaolv, Dongnong C5, Jizong A were classified into Lvda Red Cob group, CSyn3, Yuzong 5, Shanzong 3, WBM-C4 and Shanzong 1 were classified into Lancaster group.(4) The GCA effects of Pob32, Pool 19, Pob69, Pob70, CPop13, CPop14 were relatively lower, and further evaluation is needed to evaluatie the potential utilization in temperate maize breeding program.(5) The common testers can be used to test the combining ability of maize populations and OPVs, and evaluate the heterotic relationships between domestic and tropical, subtropical germplasm.