[Shifting of the flowering time in colchicum]

Potted Colchium plants were subjected to a temperature of 4°C±1° for 2 1/2 to 27 weeks between April and November (1959) and then planted in the garden.Some plants flowered during the fall of the same year in spite of the cold treatment; some of them even flowered during the cold treatment itself. In other plants, the fall flowering of that year was suppressed to different degrees depending on the treatment.Plants that had been exposed to at least 13 weeks of low temperature after the middle of July had some of their fall buds arrested in the development and only flowered in the following spring. Any earlier or later cold treatment was without effect on the time of flowering.Thus the normally fall flowering Colchium was forced by experimental means to flower in spring. This effect resembles the spontaneous spring flowering that is sometimes observed in nature and which has been subject to controversial interpretations.None of the plants that flowered in the spring following the experimental year continued this behavior during consecutive years. The fall flowering of the year following on the experimental year was also influenced by the time and duration of the cold treatment. This indicates that the effects of the cold treatment reached into the next generation of bulbs.