© 2001 Heron Publishing—Victoria, Canada
Effects of soil temperature on biomass and carbohydrate allocation in Scots pine (Pinus sylvestris) seedlings at the beginning of the growing season
Timo Domisch (1), Leena Finér (1) and Tarja Lehto (2)
1. Finnish Forest Research Institute, Joensuu Research Station, P.O.B. 68, FIN-80101 Joensuu, Finland / 2. Faculty of Forestry, University of Joensuu, P.O.B. 111, FIN-111 Joensuu, Finland / Received May 23, 2000
Summary
We studied effects of soil temperature on shoot and root extension growth and biomass and carbohydrate allocation in Scots
pine (Pinus sylvestris L.) seedlings at the beginning of the growing season. One-year-old Scots pine seedlings were grown for 9 weeks at soil temperatures
of 5, 9, 13 and 17 °C and an air temperature of 17 °C. Date of bud burst, and the elongation of shoots and roots were monitored.
Biomass of current and previous season roots, stem and needles was determined at 3-week intervals. Starch, sucrose, glucose,
fructose, sorbitol and inositol concentrations were determined in all plant parts except new roots. The timing of both bud
burst and the onset of root elongation were unaffected by soil temperature. At Week 9, height growth was reduced and root
extension growth was much less at a soil temperature of 5 °C than at higher soil temperatures. Total seedling biomass was
lowest in the 5 °C soil temperature treatment and highest in the 13 °C treatment, but there was no statistically significant
difference in total biomass between seedlings grown at 13 and 17 °C. In response to increasing soil temperature, belowground
biomass increased markedly, resulting in a slightly higher allocation of biomass to belowground parts. Among treatments, root
length was greatest at a soil temperature of 17 °C. The sugar content of old roots was unaffected by soil temperature, but
the sugar content of new needles increased with increasing soil temperature. The starch content of all seedling parts was
lowest in seedlings grown at 17 °C. Otherwise, soil temperature had no effect on seedling starch content.
Keywords:
growth, root, shoot, soluble sugars, starch.
