THE EFFECT OF THE PRELIMINARY TREATMENT OF LOW TEMPERATURE ON FORCING THE BLOOMING OF THE BROAD BEAN, Vicia Faba LINN

Abstract

In the autumn of 1935, the writer carried out an experiment to determine the effect of the preliminary treatment of low temperature on forcing the blooming of the broad bean. Using two varieties, ten experimental plots were set out as follow:
Plot 1. Seeds of the Zairai variety first soaked in water for 12 hours were placed in the refrigelator at 10°C for a period of 21 days, before they were sown in the field.
Plot 2. Seeds of the Zairai variety treated as above were cooled at 10°C for 18 days before sown in field.
Plot 3. Soaked seeds of the Zairai variety, were cooled at 10°C for 16 days, before sown in field.
Plot 4. Seeds of the Zairai variety, so treated were cooled by 5°C during 16 days, before sown in field.
Plot 5. Soaked seeds of the Zairai variety were cooled at 10°C for 10 days, before sown in field.
Plot 6. Soaked seeds of the Zairai variety were cooled by 5°C during 10 days, before sown in field.
Plot 7. Soaked seeds of the Zairai variety were cooled at 10°C for 3 days, before sown in field.
Plot 8. Seeds of the Zairai variety were soaked in water for 12 hours before sown in field. No cooling was practised.
Plot 9. Dry seeds of the Zairai variety were used without any preliminary treatment.
Plot 10. Dry seeds of the Gokuwase (Extra Early) variety were usedwithout any preliminary treatment.
Seeds of each plot were sown in the experimental field on Sep. 23. Good care was given throughout the season before they come to the blooming stage.
As shown in table 1, plant received preliminary low temperature befor sowing, showed a remarkable shortening of flowering time. The maximum shortening was obtained in plot 1, which received 21 days exposure at a low temperature of 10°C, days required for blooming being shortened to nearly one third of standard. Those plants treated by low temperature always had short node and uniform flowering.
From these facts it can be clearly said that the broad bean is very sensitive to low temperature at the germinating stage, being functionally stimulated to reduce the time required for blooming. If a mass treatment is conducted with the broad been seed on a commercial scale, the time of cropping can be brought very early giving a large profit to the grower.
It is believed that the similar response will be expected with some other vegetables, and the idea that the earliness of vegetable crops can be attained by the other means than selecting early variety, will be introduced. This will lead to a great change in the future prospect of vegetable forcing when vernalization practice becomes greatly popularized.