Analysis Of Genetic Relationships Among Twenty Maize Populations And Identification Of Populations Useful For Improving An Elite Single Cross

Introgression of exotic maize (Zea mays L) germplasm is an effective approach to increasing geneticvariation and broadening maize genetic base. Recently, many exotic germplasm, included tropical,subtropical and U.S. were introduced into China, which needs to analyze genetic relationship betweenthese germplasm and Chinese germplasm, in order to improve Chinese germplasm. In the study,20maize populations from CIMMYT, U.S. and China, four Chinese testers included by Csyn5(Sipingtougermplasm), Csyn7(PA germplasm), Lancaster (Lancaster germplasm) and BSSS (Reid germplasm)were crossed according to the partial diallel mating scheme. The24populations and their partial diallelcrosses were evaluated at Shenyang, Gongzhuling and Shunyi in2009-2010in a generalized latticedesign. Our objective was to assess variety effect, variety heterosis and general combing ability of24populations; heterotic relationships between20populations and four testers using Miranda Filho andGeraldi (1984) model; the potential of U.S., CIMMYT and Chinese maize populations as donors offavorable alleles for improving an elite hybrid Jidan261. The results as follows:1. General combing ability (GCA) effect of20populations can be effectively estimated in crosseswith different heterotic patterns: Csyn5and Csyn7, Lancaster and BSSS, respectively. Csyn5andLancaster are better testers to analyze genetic relationship between exotic and Chinese germplasm inNorthest of China.2. It was estimated that Pob43, Suwan1from CIMMYT, Jilin Syn A, Csyn3, Csyn4, Yu Syn5,WBMC-4from China, BS29from U.S. had better variety effect and general combing ability for a fewagronomic traits. However, Pob43, Suwan1, Jilin Syn A, WBMC-4should be monitored carefully inpractical breeding because of pooly performance for plant height and growth period.3. Based on the heterotic pattern Lancaster×Csyn5in spring sowing zone in Northeast of China,Pob28, Pob446, QPM-Y, Shan syn3, Yu Syn5, WBMC-4, BS28, BS29and BS30showed closergenetic relationship to Lancaster germplasm; Pob43, SG-Y, Suwan1, Tuxpeno, Liaolv syn, Csyn3,Csyn4, BS16, BSCB1showed closer genetic relationship to Sipingtou germplasm.4. Based on relationship between TCSC, PTC and Lplμ’ estimators, TCSC–PTC was recommendedthat TCSC was estimated to select a few populations with favorable alleles to improve elite hybridsfrom mass maize germplasm, and then PTC was used to accurately rank the highest populationscontaining favorable alleles not present in elite hybrids.5. CIMMYT, U.S. and domestic populations had potential as donors of favorable alleles forimproving an elite hybrid (W9706×Ji853) for a few agronomic traits. For example, Jilin syn A cansimultaneously improve ear length, ear diameter, kernel number per row, kernel length,100-kernelweight, and grain yield of W9706×Ji853. Csyn4can simultaneously improve ear length, ear diameter,kernel number per row, kernel length, and grain yield of W9706×Ji853. Pob43can simultaneouslyimprove ear length, kernel number per row, kernel length, and grain yield of W9706×Ji853. BS30cansimultaneously improve ear diameter, ear row number, kernel number per row, and kernel length.WBMC-4can simultaneously improve ear length, kernel number per row, and grain yield of W9706× Ji853. Suwan1and Csyn3can all simultaneously improve ear diameter, kernel length, and grain yieldof W9706×Ji853.6. In short, Chinese elite germplsm (Jilin syn A, Csyn4, Csyn3, and WBMC-4), and exotic elitegermplasm (Pob43, Suwan1, and BS30) can be donors to improve Sipingtou or Lancaster germplsm.Especially, they had great potentialities to simultaneously improve W9706×Ji853for several traitsmeasured. However, pooly performance of tropical populations Pob43, Suwan1for plant height andgrowth period shoud be carefully monitored. It was recommended that establishing compoundpopulations using these tropical germplasm and Chinese germplasm could be better donors to improveelite hybrids.