Breeding radish for winter production under glas: Phytotron investigations for the development of a selection method

1 . When radish is grown during the winter in cold glasshouses it frequently happens that no full grown fleshy roots are formed but bolters . This investigation is concerned with the factors which are most important in controlling the development of the radish plant, and with the cause of this lack of root thickening . 2. It appeared that an annual radish plant will ultimately bolt under any normal set of conditions, but that the rate of bolting is increased by high temperature and a long photoperiod . 3. Root thickening is possible only if the planting distances are not too narrow and if there is enough light in relation to the temperature . 4. From a cultural standpoint the remedy is : give the plants enough space, keep the temperature down, and utilize the available light . 5. To breed plants more adapted to the unfavourable conditions, they should be grown and selected under conditions of rather high temperature and relatively low light intensity .