Epsilon Open Archive

Abstract

The effect of varying amounts of potassium, calcium, and magnesium on water contents, transpiration rates, and frost hardiness of unhardened and 3 weeks' hardened seedlings of Pinus silvestris L. was investigated. The seedlings were 12 and 15 weeks old, respectively. A hardening period of three weeks (short days: 8 hours light and low temperature: 3°C) decreased the water content of the shoots by 1-6 per cent, and the transpiration rates by about 50 per cent. Increased potassium content increased the water content of the shoot, but decreased the transpiration rate. Increased magnesium content increased the water content, but did not affect transpiration rate. Increased calcium content had no significant effect on water content or transpiration rate. Different contents of potassium, calcium, and magnesiuin had no effect, or only a very small effect, on frost hardiness in unhardened or 3 weeks' hardened seedlings. A transport of potassium from the root to the shoot during hardening was demonstrated and this transport is discussed in connection with winter survival.