Heterosis and Hybrid Seed Production in Fodder Grass

Abstract

The best way to use heterosis in crops is the production of pure F1 hybrids which have a high degree of heterozygosity. But when fodder grass breeding started the breeders could not afford to invest too much money and labour. At that time the farmers did not realize the advantage of a cultivar and therefore they were not ready to buy grass seed which was inevitably highly priced. In the beginning of forage grass breeding it was not possible to copy directly the successful breeding scheme which allowed maize breeders to evolve high-yielding hybrid varieties. But after the polycross method was described by different authors, the varieties known as synthetics could be developed very easily in grasses (Frandsen 1940; Tysdal et al. 1942; Wellensiek 1952). The poly cross test enabled the breeder to select clones with a good general combining ability. These genotypes form the initial generation (Syn0) and the seed of a consecutive generation can be sold to the farmer. By application of this method a small part of heterosis is exploited. Many cultivars of today are synthetics. Breeders and scientists, however, repeatedly tried to utilize more heterosis, and about 20 years ago Myers said: ``The time has come for forage breeders to move forward with a bold program to make use of the maximum amount of heterosis possible with the material at hand. To accomplish that, first-generation hybrids must be used in farmers' field'' (Myers 1960).