© 1987 Heron Publishing—Victoria, Canada
Nitrate metabolism in Scots pine seedlings during their first growing season
T. Sarjala (1), R. Raitio (1, 2) and E.-M. Turkki (3)
1. Finnish Forest Research institute, Parkano, Finland / 2. Author to whom correspondence should be addresssed / 3. Department of Botany, University of Oulu, Finland / Received March 5, 1987
Summary
Fluctuations in nitrate reductase activity (NRA), nitrate, nitrite, protein and total nitrogen content of bare-root Scots
pine seedlings (Pinus sylvestris L.) raised outdoors were investigated during the first growing season. Nitrate reductase activity was higher in roots than
in needles, whereas NO3– content was higher in needles than in roots and increased in both from June to October. Nitrate reductase activity in roots
correlated more closely with NO3– N in the soil than did NO3– in the roots. In autumn, there was a closer correlation between foliar NRA and NO3– in the needles than with NO3–-N in the soil. Nitrite was not detected in the seedlings during the growing season. Total nitrogen content decreased toward
the autumn, whereas protein content initially decreased but increased again in autumn. Acrylic netting placed above the seedlings
increased both air and soil temperatures and apparently accelerated the use of nitrate.
