engleski

Comparing Methods for Integrating Exotic Germplasm into European Forage Maize Breeding Programs

In order to broaden the genetic base of germplasm for forage maize (Zea mays L.), it is necessary to integrate exotic materials into adapted breeding populations. The aim of the study was to compare several methods of integration by evaluating 18 initial crosses between adapted (recipient) and exotic (donor) elite dent inbred lines with regard to their testcross performances. Specific objectives were i) to assess the effects of backcrossing the F1 to the recipient and intermating the F2 generation ; ii) to determine the benefit of selection for earliness and iii) to examine the influence of the recipients and donors on the integration methods. Three foundation populations were developed from each of the initial crosses: F2, F2-Syn2 (: F2 twice intermated), and BC1. Fifty S1 lines were produced from the 4.4% earliest S0 plants of each foundation population. Bulks of these S1 lines along with the pertinent F1s and recipient parents were testcrossed with an adapted flint line. The testcrosses were evaluated in field trials at three locations in southern Germany in 1994 and 1995. Whole plant quality traits were investigated by near infrared spectroscopy (NIRS). Differences between generation means were significant for all agronomic traits and for starch content and crude protein content. For dry matter yield, the effect of backcrossing varied among the initial crosses, while the influence of intermating was non-significant in most instances. Averaged across all generations, initial crosses which had inbred lines B73 or Mo17 as donors were superior to all other exotics for dry matter yield without being later in maturity. For maturity, the effects of backcrossing, intermating, and selection for earliness generally were all germplasm-specific. This suggests that the choice of germplasm is more important than the integration method.

maize; exotics; integration methods

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