Effects of nutrient loading in Lutz spruce seedlings (Picea x lutzii Littl.) during nursery rotation and on subsequent growth in field

Sammanfattning: 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 growthcapacity and nutrient status after the nursery rotation. The total biomass of loaded seedlingswas similar to unloaded seedlings after the nursery culture, but the increase in N from thenutrient loading was 29%, 41% and 48% for loaded treatments 7.8 – 31.4 mg N, respectively. Adelay in accumulation of frost hardiness during the autumn was not detected, and the rootgrowth 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 contentafter 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 inthe field had on average 31% and 52% more dry mass than unloaded treatments withoutfertilizer at sites A and B, respectively, after one growing season in field. Field fertilization alsoincreased total shoot mass on average by 35% and 52% at sites A and B, respectively. Theloading 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 averagein loaded treatments by 33% and 33% at site A and B, respectively. Nitrogen retranslocationfrom old to new needles was detected. The results illustrate the significance of retranslocationof stored nutrients to support new growth early in the season when root growth and nutrientuptake are still low. Survival was not affected by the nutrient loading after the first growingseason, but fertilizing significantly decreased the damage caused by Otiorhynchus larvae inheath land. It was concluded that loading might provide an additional input for faster plantationestablishment during the first crucial growing season after planting.