Study on Utilization of Tropic and Sub-tropic Maize Germplasm in Northern Early-Mature Spring Maize Breeding

Eight inbred lines were selected by introducing tropic maize germplasm into Diangu11A,Hongyumi,Chang3,Mo17,2 test varieties were selected for each inbred line.Contrast design,three replications.The observed values of agronomic traits of selected lines with tropic and subtropics germplasm and unimproved lines,hybrids of the selected inbred lines and the cross combinations of unimproved lines were taken as a pair of data and analyzed by pairing statistical method,t test.The results showed that the heterosis of hybrids crossed by Diangu11A induced Suwan1,5-56 and Hongyumi,Hongyumi induced Suwan1,EVT5 and Diangu11A,Chang3 induced Suwan1,Mo-huang9 and Hai014 were all higher than the adjacent control groups.The main agronomic traits change of inbred lines induced into tropical germplasm was the delay of growth period.The earlier mature period of induced inbred lines,the longer growth period of relevant newselected inbred lines and crossed hybrids.All the plant yield of tropic germplasm introduced inbred lines get improved.The earlier mature period of induced inbred lines,the higher increase yield range of tropic germplasm introduced inbred lines than unimproved lines.The northern leaf blight and stalk rot resis-tance of tropic germplasm introduced inbred lines and crossed hybrids had improved widely while the pathogenesis degree of head smut showed difference.