Abstract
Abstract This study aimed to evaluate hybrids obtained by the cross among temperate × tropical elite maize lines, and to determine the genetic diversity and population differentiation of these inbred lines. Forty-nine hybrids were evaluated for seed yield, plant and ear heights, and for severity of Phaeosphaeria maydis and Exserohilum turcicum in four environments in Brazil. Hybrids were obtained from a partial diallel that involved seven tropical and seven temperate lines. Twenty-two SSR primers were used to evaluate the genetic relationship among the lines. Diallel showed the existence of significance for GCA and SCA effects; the genetic control of the traits was associated with additive and non-additive genetic effect. Results showed that exotic and previously protected temperate maize germplasm may provide novel alleles for resistance to P. maydis and E. turcicum and increase yield in tropical maize. Tropical inbred lines were allocated in different heterotic groups, suggesting an admixture condition among temperate and tropical materials.
Highlights
Maize breeding programs are based on the development and selection of hybrids obtained from inbred lines
The available Brazilian maize germplasm collection has been used to increase the development of hybrids with high performance, high yield potential, and with stability and adaptability to different regions
The heterotic patterns used for maize breeding program in the US Corn Belt have impacted breeding by largely predetermining the type of germplasm used in research programs over a long period of time (Reif et al 2005)
Summary
Maize breeding programs are based on the development and selection of hybrids obtained from inbred lines. This method is easy to perform; developing inbred lines with high performance is time-consuming. For this reason, and considering the high demand for maize around the world, government institutions and private companies have focused in developing superior hybrids with high performance and stable adaptation throughout different regions, climates, and sowing time. The available Brazilian maize germplasm collection has been used to increase the development of hybrids with high performance, high yield potential, and with stability and adaptability to different regions. The heterotic patterns used for maize breeding program in the US Corn Belt have impacted breeding by largely predetermining the type of germplasm used in research programs over a long period of time (Reif et al 2005)
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