Effects of nutrient loading in Lutz spruce seedlings (Picea x lutzii Littl.) during nursery rotation and on subsequent growth in field
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 ze:12. 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. Key word: Lutz spruce seedlings, nutrient loading, frost hardiness, root growth capacity, biomass allocation, N content, N concentration, growth, survival, retranslocation.
Hvítgreni, Frostþol, Lífmassi, Vöxtur, Lifun
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