ABSTRACT In Nordic climates, the weather allows a narrow time window during spring and summer for forest seedlings to be transplanted from indoor growth to outdoor conditions. If a new method for year-round cultivation under LED lamps is to be successfully introduced in forest nurseries, a cold storage phase for batches produced outside of the vegetation period needs to be included in the concept. Different short-day treatments for induction of cold hardiness in very young seedlings of Picea abies and Pinus sylvestris cultivated solely under LED lamps were investigated. The study compared a combination of two photoperiods (5 h or 8 h) at three different temperatures (5°C, 10°C or 20°C) applied during five weeks. Chlorophyll fluorescence, shoot electrolyte leakage and molecular testing for gene expression of cold acclimation were used to assess the treatments. After a period of three months in cold storage at 2°C, the vitality of the seedlings was evaluated using a root growth capacity test. Lower temperatures during the treatments, especially for Pinus sylvestris, had a significant effect on inducing cold hardiness. The results showed that the photoperiod should not be overly reduced to allow photosynthesis and generation of carbohydrate reserves but it could be optimized to reduce electricity consumption.

中文翻译：

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在 Picea abies (L.) Karst 中诱导抗寒性的处理。和在发光二极管下预栽培的樟子松幼苗——光周期和温度的影响，包括冷藏后的能量消耗和幼苗质量

摘要 在北欧气候中，春季和夏季的天气允许林木幼苗从室内生长移植到室外条件的时间窗口很短。如果要在林木苗圃中成功引入 LED 灯下全年种植的新方法，则需要在概念中包括对植被时期之外生产的批次进行冷藏阶段。研究了不同的短日照处理，以诱导仅在 LED 灯下栽培的云杉和樟子松幼苗的抗寒性。该研究比较了在五周内应用的三种不同温度（5°C、10°C 或 20°C）下的两种光周期（5 小时或 8 小时）的组合。叶绿素荧光，使用芽电解质渗漏和冷驯化基因表达的分子检测来评估处理。在 2°C 下冷藏三个月后，使用根系生长能力测试评估幼苗的活力。处理过程中较低的温度，特别是对于樟子松，对诱导抗寒性有显着影响。结果表明，不应过度减少光周期以进行光合作用和产生碳水化合物储备，但可以对其进行优化以减少电力消耗。