| In this study, 45 maize inbred lines were employed to study the interrelationship among traits of seedling emergence rate, root number, root length, mesocotyl length, coleoptile length, mesocotyl and coleoptile total length, seedling length, and deep-sowing tolerant characteristics at 10 cm and 15 cm sowing depth. The results showed that root length, mesocotyl length, coleoptile length, mesocotyl and coleoptile total length increased, and seedling emergence rate, root number, seedling length decreased with sowing depth. And there were different variable coefficient of the traits at different sowing depth, with seedling emergence rate and coleoptile length showing largest variations whereas root length, root number and mesocotyl length being the least. Correlation analysis showed that seedling emergence rate at 10 cm sowing depth was significantly positively correlated with coleoptile length, root length and seedling length. Seedling emergence rate at 15 cm sowing depth was positively correlated with mesocotyl length, mesocotyl and coleoptile total length, root number, root length, seedling length. The findings for the 15 cm sowing depth could reflect deep-sowing tolerant ability in different maize lines. Therefore, according to strong or weak deep-sowing tolerant ability, 45 maize lines were categorized into three groups, using parameters including seedling emergence rate, root number, root length, mesocotyl length, mesocotyl and coleoptile total length and seedling length at the 15 cm sowing depth. Further, these 45 inbred lines could be classified into six sub-groups (Lancaster, Sipingtou, PA, PB, BSSS and Luda Red Cob), which agreed with the recorded pedigree. Marked differences were observed for mean seedling emergence rate, root number, root length, mesocotyl length, mesocotyl and coleoptile total length and seedling length among the six sub-groups at the 15 cm sowing depth. Analysis showed that the values for Lancaster, Sipingtou and PA were relatively higher, exhibiting strong to medium deep-sowing tolerant, and are elite germplasms for improvement of deep-sowing tolerant maize. |