Influence of various sources of nitrogen on the growth of Scots pine seedlings and the IAA content in needles

One year old pine seedlings transferred from the nursery and potted in a greenhouse were watered with nitrogen solutions of different form and concentration (urea 0.36 mM and 0.90 mM, ammonium tartrate 0.36 mM and 1.79 mM, calcium nitrate 0.36 mM, 1.79 mM and 3.58 mM). After 10 months the growth and IAA content in needles were compared. Nitrogen fertilization affected shoot growth considerably, but its effects on root growth were less pronounced. The highest shoot weight was obtained after application of ammonium tartrate in 1.79 mM concentration. The lowest concentration of urea (0.36 mM) caused the same effect, as did the most concentrated calcium nitrate solution (3.58 mM). Auxine content increased in the needles after nitrogen fertilization as compared with control. The highest accumulation of IAA was found in seedlings treated with low concentrations of urea