ABSTRACT

Planting healthy seedlings with optimal growth potential is essential for proper growth and survival in forest regeneration. Assessing the seedling quality prior to planting is therefore important. In this Icelandic study, effects of root damage induced with artificial freezing in young Russian larch seedlings were examined using the root growth capacity method (RGC). Frost tolerance of roots varied during the winter, and root growth in undamaged seedlings fluctuated, indicating seasonal variations in growth rhythm. The LT₅₀ value for root frost tolerance was −13.9°C in late January, but already at −10.6°C (LT₁₀) root damages were severe. After one growing season, shoot elongation was significantly lower in seedlings frozen to −9°C, −13.5°C, and −15.5°C by 23%, 54%, and 72%, respectively, compared with undamaged seedlings. Control seedlings and seedlings frozen to −9°C achieved 100% survival after the first growing season. Survival in seedlings frozen to −13.5°C and −15.5°C was 85% and 27%, respectively. After the second growing season, survival decreased in all frost-damaged seedlings. The ongoing mortality demonstrates the long-lasting effects of planting seedlings with damaged root systems, and the fluctuation in root frost tolerance of young Russian larch seedlings during winter emphasises the need for care when seedlings are moved to outdoor storage.

摘要

种植具有最佳生长潜力的健康幼苗对于森林再生过程中的正常生长和存活至关重要。因此，在种植前评估幼苗质量非常重要。在冰岛的这项研究中，使用根系生长能力法 (RGC) 检测了人工冷冻对俄罗斯落叶松幼苗根系损伤的影响。冬季根系的抗冻性不同，未受损幼苗的根系生长波动，表明生长节律存在季节性变化。根部抗冻性的LT _{50值在 1 月下旬为 -13.9°C，但已经达到 -10.6°C（LT 10}) 根部损坏严重。一个生长季后，与未受损的幼苗相比，冷冻至 -9°C、-13.5°C 和 -15.5°C 的幼苗的枝条伸长率分别显着降低 23%、54% 和 72%。对照幼苗和冷冻至 -9°C 的幼苗在第一个生长季后实现了 100% 的存活率。冷冻至-13.5°C 和-15.5°C 的幼苗存活率分别为85% 和27%。在第二个生长季之后，所有受霜害的幼苗的存活率都下降了。持续的死亡率表明种植根系受损的幼苗会产生长期影响，而俄罗斯落叶松幼苗在冬季根部抗冻性的波动强调了将幼苗移至室外储存时的护理需求。