| Sumario: | Lutz spruce (Picea x lutzii Littl.) seedlings were nutrient loaded using four fertilization regimes, receiving in total 0, 7.8, 22.2 and 31.4 g N/m2 over a period of eight weeks (6th august – 27th September) to investigate the effects on biomass allocation, frost hardiness, root growth
capacity and nutrient status after the nursery rotation. The total biomass of loaded seedlings
was similar to unloaded seedlings after the nursery culture, but the increase in N from the
nutrient loading was 29%, 41% and 48% for loaded treatments 7.8 – 31.4 mg N, respectively. A
delay in accumulation of frost hardiness during the autumn was not detected, and the root
growth capacity was not affected by the nutrient loading when measured the following spring.
To investigate if the internal N status of the seedlings affected growth, survival and N content
after one growing season in field, the seedlings were planted at two field trials (sites A and B),
with or without field fertilizer. The shoots of loaded treatments without fertilizer application in
the field had on average 31% and 52% more dry mass than unloaded treatments without
fertilizer at sites A and B, respectively, after one growing season in field. Field fertilization also
increased total shoot mass on average by 35% and 52% at sites A and B, respectively. The
loading treatments without field fertilization increased N content in current needles by 104%
and 109% for sites A and B, respectively. Field fertilization also increased N content on average
in loaded treatments by 33% and 33% at site A and B, respectively. Nitrogen retranslocation
from old to new needles was detected. The results illustrate the significance of retranslocation
of stored nutrients to support new growth early in the season when root growth and nutrient
uptake are still low. Survival was not affected by the nutrient loading after the first growing
season, but fertilizing significantly decreased the damage caused by Otiorhynchus larvae in
heath land. It was concluded that loading might provide an additional input for faster plantation
establishment during the first crucial growing season after planting.
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