Vernalization

Vernalization (Latin vernalis "Spring " ) or vernalization (Russian jarowoi "Summer " ) refers to the natural induction (excitation ) of bolting and flowering in plants by a longer period of cold weather in winter.

Many one and two- year-old plant species shot in regions with marked differences between winter and summer conditions and bloom only after they have been through a sustained period of low temperatures. This prevents the onset of the reproductive phase in the unfavorable time for the plant before winter.

Leading the way in vernalization research was Gustav Gassner. The practical application of vernalization in Russian agriculture goes back to the Russian scientist Trofim Denisovich suggestions Lysenko. In the reign of Josef Stalin's methods of Lysenko were temporarily official science doctrine of the Soviet Union ( Lysenkoism ).

Demarcation

Vernalization must be distinguished from stratification, by which the artificial treatment of seeds is meant to promote their germination. It can, as well as vernalization, carried out by cold treatment of the seeds.

The production and the cultivation of plants Frigo is no vernalization, but the artificial prolongation of hibernation for influencing the harvest time.

Importance of crops

Non- crop plants in which the vernalization plays an important role, are the cereals. This winter and spring cereals are distinguished. Winter cereals are sown in the fall, overwinter as small plants and shot next spring.

To the continental climate of Siberia to sow profitable winter crop in the spring, a few years has been " artificially vernalized ", ie brought in freezing weather the winter cereal seed in special buildings by the addition of moisture and heat in vernalization, then doors and windows were open for a few hours, to the seed exposed to the low temperatures. This " artificial vernalization " existing in winter cereals lap inhibition was eliminated and the winter crops schossten and flourished even in spring sowing. Through the vernalization of summer grain was trying to extend their Saatperiode.

After Stalin's agricultural reform were not enough seeders available; through artificial vernalization of seeds, the income risks could not later be prevented sowing, but partially reduced. By better equipping seeders and the introduction of new high-yielding summer cereals vernalization of Russian agriculture is soon gone.

When using the optimum Saatzeitpunktes there is no need for artificial vernalization.

An example of an undesirable vernalization are the bolters in sugar beet, which occur when experienced after sowing in spring, the seed in the ground late frosts.

Physiology

The cold period and the flowering process can be separated in time relatively far apart. This means that does not have to take place immediately at the beginning of the warmer period of the flowering process. Here some additional factors such as day length, temperature, and state of development of the plant play a role. Plants are able to "remember " the lived cold spell to. Thus, in some species can be done in the seed stage, the vernalization already, but the plant blooms only at much later stages of development.

The vernalization appears to act primarily at the shoot apical meristem. If other parts of the plant such as the leaves, low temperature exposure, no vernalization occurs. Another observation is that the vernalisierte state of a plant can not be transmitted by grafting. For example, if a non vernalisierte shoot tip grafted onto a vernalisierte base, this shoot tip also shows a unvernalisiertes flowering behavior. This finding also suggests that the vernalisierte state is not spread over a greater distance in the plant and the vernalization acts directly on the vital tissues, namely the shoot apical meristem.