Improvement and usage of three semi-exotic maize populations constructed with CIMMYT germ plasm

The heterosis and combining ability of some maize lines selected from three semi-exotic populations constructed with CIMMYT tropical or sub-tropical germ plasm and temperate lines were tested to study their improvement effects and cross direction in China.The results showed that lines selected from semi-exotic population Dan340×Pob70 had higher general combining ability and the heterosis when crossed with lines in the Lancaster group and the improved Reid group.The lines selected from semi-exotic population Pob101×Ye478 had medium general combining ability and higher heterosis when crossed with lines in the Ludahonggu group.The lines selected from the semi-exotic population Ye107×Pob69 had lower general combining ability and medium heterosis when crossed with lines in the Ludahonggu group.