Preliminary Study On Combining Ability And Heterotic Grouping In Temperate And Subtropical Maize Lines

The heterotic groups, heterosis and combining ability of 18 temperate normal maize (Zea mays L.) , 6 local QPM and 22 CIMMYT subtropical QPM inbred lines were studied by two sets of experiments which were carried out in two years and two locations, according to NC1I mating design. The heterotic groups and genetic distance of 46 lines were studied with SSR markers. The main results of the present study were summarized as follows:1.Eighteen temperate normal lines were classified into five heterotic groups by yield SCA (special combining ability): Lancaster including Mo17 and P 138; Reid including B73, U8112 and Tie7922; Sipingtou including Huangzao 4 K12, 515 and Ye107; Luda Red Cob including Dan340, E28, Zi330, S37 and 8-93; PN group including K22, CA 156, Ye478 and Shen 5003.2.In CIMMYT QPM , lines derived from Pool 32, UWO, WOMTA and CYO germplasm can be used to improve CA375 and CA339, as these lines performed lower SCA with CA375 and CA339 than with Qi205. Lines derived from Pool 34 and UYO germplasm can be used to improve Qi205, as these lines performed lower SCA with Qi205 than with CA375 and CA339. Lines from other germplasm did not perform significant different yield SCA with 3 testers.3.The performance ofKl2X8-93, B73XS37, 873X8-93, K22XS37, MoI7X8-93, MoI7XS37, Dan34OXTie7922, Dan34OXPI38 and Dan34OXS37 were performed higher among 72 normal maize combinations. Inbred lines K12, S37, 8-93 and Dan340 were good combiners and involved to produce high yielding combinations and will be predominant parent lines in hybrid maize breeding program and commercial maize production in China.4. Among 66 QPM combinations, Qi205 X CML181, Qi205 X CML182, CA339 XCMLl94, Qi205 x CMLl79, Qi205 X CMLl78, CA339 X CMLl92, Qi205 X CMLl93 andCA375 x CMLl81 performed higher yielding potential. Inbred lines CMLl8l, CMLl82,CMLl94, CML179 and CMLl93 possessed higher GCA, and showed promising to be usedto improve the local QPM lines.5. Forty-six inbred Iines were cIassified into tWo groups and the first group weredivided into six sub-groups by UPGMA (Unweighed Pair Group Method ArithmeticAverage) based on SSR markers. Inbred lines Mol7 and CMLl8l showed closer geneticdistance. Reid lines and CMLl74, CMLl75 showed higher genetic similarity. Luda RedCob group and CMLl80, CMLl87, CMLl88 showed closer genetic distance. Thesesubtropical lines can be used to improve temperate normal lines and recycle new QPMlines.