Crossing and selection

Crossing

Breeders want to provide agrarians with optimally adapted crops. This requires combining many positive characteristics in one single variety. The desired properties include a very good yield, resistance to pathogens, a high starch, protein or sugar content, and good standability in the field. To be able to combine all these properties in one single variety, parent plants carrying the desired characteristics are cross-bred. This creates a filial generation.

In the best-case scenario, this will include a few individual plants that carry the positive traits of both parents. Only then does the crossing experiment have the desired result. In a next step, breeders cross-breed this offspring with other plants that have other desired properties. Several cross-breeding stages later, a new line is created that ultimately combines all beneficial characteristics and, after several test phases, can be registered as a new variety. This process is time- and labour-intensive. It must be carefully planned and implemented over several years.

Selection (screening)

Selection (also called screening) is the oldest form of plant breeding. Around 12,000 years ago, humans initially cultivated wild cereal grains. The early farmers purposefully held back the grains of the largest and most productive plants. These seeds were then sown again the following year, while all other plants were excluded from the breeding process. This allowed the desired properties of the plants to assert themselves more and more over time. Among other things, the yield was increased.

If this selection process is repeated often enough, eventually only almost homozygotic plants (with regard to the selected characteristic) remain that have the desired properties. Without knowing the genetic principles, the first farmers managed to carry out selective breeding through accurate observation and their experience. One of the first cultivated cereal crops was wild einkorn (Triticum urartu). It grows only a few small grains and its ears are brittle. Constant selection of the best individual plants then led to cultivated einkorn (Tritium monococcum) with larger grains and solid ears.