An Assessment of Storability of Norway Spruce Container Seedlings in Freezer Storage as Affected by Short-Day Treatment
An Assessment of Storability of Norway Spruce Container Seedlings in Freezer Storage as Affected by Short-Day Treatment
复制标题
短日照处理对挪威云杉容器苗冷冻储存的耐贮性评估
作者：
J. Riikonen;J. Luoranen
在林木苗圃中，确定将苗木转移到冷冻库的安全时间是一个问题。本研究旨在确定不同植物部位的贮藏前抗冻性（FH）、干物质含量（DMC）、冷藏时间（温度在-5°C至+5°C之间的时间总和）和贮藏后活力之间的关系，以及短日照（SD）处理对这些关系的影响。秋季期间，将一年半的挪威云杉对照苗和 SD 处理苗五次转移至冷冻库（-3°C）。每次测定芽、针叶、茎和根的 FH 以及 DMC，并计算冷藏时间。冷冻保存的幼苗的活力是通过随后春季的根系生长能力以及随后两个生长季节结束时幼苗的田间表现（枝条生长和幼苗损伤）来确定的。在两种处理中，当针的 FH 至少为 -25 °C，并且根的 FH 为约 -10 °C 时，幼苗被认为是可储存的。过早贮藏降低了幼苗的活力。 SD处理并没有提高幼苗的耐贮性，尽管它通过提高针叶和茎的FH（但不是根的FH）减轻了早期储藏的一些负面影响。 SD 处理的幼苗的 DMC 值（表明耐贮性）高于对照幼苗。将在 Suonenjoki 进行的五次实验的数据结合起来，发现冷时数累积与针叶 FH 之间的关系取决于苗圃处理和评估年份，这降低了使用冷时数预测挪威云杉幼苗耐贮性的可靠性。预测的气候变化可能会使幼苗的秋季驯化变得复杂。迫切需要新的、用户友好的方法来确定幼苗的耐贮性。
Determination of safe times at which to transfer seedlings to freezer storage is problematic in forest tree nurseries. The present study aimed to determine the relationship between pre-storage frost hardiness (FH) of different plant parts, dry matter content (DMC), chilling hours (the sum of hours when temperature was between −5 °C and +5 °C), and post-storage vitality, and the impact of short-day (SD) treatment on these relationships. One and a half year old control seedlings and SD-treated seedlings of Norway spruce were transferred to freezer storage (−3 °C) on five occasions during autumn. On each occasion, the FH of buds, needles, stem, and roots, as well as DMC, were determined, and chilling hours were calculated. The vitality of the freezer-stored seedlings was determined through their root growth capacity in the subsequent spring, and through the field performance of the seedlings (shoot growth and seedling damage) at the end of the following two growing seasons. Seedlings were considered to be storable when the FH of the needles was at least −25 °C, and the FH of the roots was about −10 °C in both treatments. Early storage reduced the vitality of the seedlings. SD treatment did not advance the storability of the seedlings, although it alleviated some of the negative effects of early storage by improving the FH of needles and stem, but not that of the roots. The DMC value, indicating storability, was higher for SD-treated seedlings than for control seedlings. When data from five experiments conducted in Suonenjoki were combined, it was found that the relationship between accumulation of chilling hours and needle FH was dependent on nursery treatment and assessment year, which reduces the reliability of using chilling hours in predicting the storability of Norway spruce seedlings. The predicted climate change may complicate the fall acclimation of seedlings. New, user-friendly methods for determining storability of seedlings are urgently needed.