Abstract
1. A study was made on pollen germination and tube growth in relation to low temperature, in broad-bean and garden-peas, flowered in midwinter, and the limit of setting in low natural temperature was studied.
2. The optimum temperature for germination of pollen was about 20°C for broad-bean, and 25°C for garden-peas. But the resistance to low temperature of these pollen was so strong, that they germinated and developed at 0°C for thereabout.
3. After certain period of time the tube growth would go at 0°C or thereabout just as much as at optimum temperature in broad-bean, but it was not true of garden-peas, the growth being very weak. And in the diary variation of room temperature, the tube growth was retarded when the temperature decreased to about 10°C in garden-peas, but it was not effected in broad-bean.
4. There was no injurious effect of low temperature, 0°C or thereabout, on already developing pollen tubes, in both broad-bean and garden-peas.
5. It seemed that the power of tube growth at low temperature was greater in broad-bean than in garden-peas.
6. The flowers opened at low temperature, 0°C or thereabout, were not dropped in out-door condition.
