Effects of temperature on shoot growth in northern provenances of Pinus sylvestris L.

Effects of temperature on shoot growth in northern provenances of Pinus sylvestris L. were studied under natural long-day conditions (Lat. 69 degrees 39' N) at controlled temperatures. The optimum constant temperature for formation of stem unit primordia in the terminal resting bud was 18 to 21 degrees C. Stem unit number decreased linearly with temperature between 15 and 9 degrees C. Temperature during bud formation had a significant effect on final stem unit length achieved in the following year. Final shoot length was significantly affected by temperature during shoot elongation. The optimum constant temperature for elongation growth was 18 to 21 degrees C. The rate of shoot elongation was positively correlated with the number of stem units.