CONTRIBUTION TO BREEDING OF VEGETABLE CULTIVARS IN FORCING HOUSES
Recently, certain progress is noted not only in tomatoes but also in cucumbers. Cucumbers have acquired great economic importance as greenhouse crop. The main reason for this is that they are a culture which has been especially bred for forcing. It may be said that on the basis of this experience a new technology of greenhouse and hotbed vegetable growing has been created.
Far back in history, the Roman emperor Tiberius was very fond of cucumbers and wanted to have them throughout the year. That is why cucumbers were artificially grown in special cases, carefully topdressed and protected from external influences - the beginning of the present greenhouse and hotbed vegetable growing.
The specific conditions which the grower creates for the development of greenhouse and hotbed crops call for special breeding.
Protected crops receive all basic nutrients in the optimal degree. That is why it is necessary to develop such cultivars that not only can thrive and develop well under these conditions but also may use them to the best advantage in a brief period of time. Here more than anywhere else the principle breeding is valid to be conducted in the conditions under which the crop will best be grown in practice.
It is further necessary to call attention to the problem of plant resistance. It is of great importance for cultivars intended for forcing in some respects even more important than for cultivars grown under ordinary conditions.
The optimal conditions created for forced crops is the reason for these plants to be rather susceptible. Analogous phenomena are frequently met with in nature and they show that excessively productive organisms,