Long and Short Term Development of Frost Hardiness in Pinus silvestris, and Heavy Particle Adenosine Triphosphatase

The effect of different growth temperatures, of transfer between them, and of changes in outside temperature on frost hardiness and ATPase activity of Scotch pines (Pinus silvestris L.) were studied. Plants which had been grown in the greenhouse and transported to outside “remembered” something of their earlier growing circumstances during a long period. They differed from the plants continuously grown outside in the level of hardiness, although changes in temperature caused similar fluctuations in the hardiness of both groups. It is evident that two mechanisms are present, the one causing a long term determination of the level of frost hardiness obtainable, the other causing a short term adaption. The heavy particle ATPase activity as investigated below 20°C grouped itself according to the main temperature groups of the experiment. Above 30°C, the pretreatments had given rise to differences within the temperature groups. The level of the ATPase activity increased as the growing season came closer.