Søgaard Gunnhild, Johnsen Oystein, Nilsen Jarle, Junttila Olavi
Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 As, Norway.
Tree Physiol. 2008 Feb;28(2):311-20. doi: 10.1093/treephys/28.2.311.
Detailed knowledge of temperature effects on the timing of dormancy development and bud burst will help evaluate the impacts of climate change on forest trees. We tested the effects of temperature applied during short-day treatment, duration of short-day treatment, duration of chilling and light regime applied during forcing on the timing of bud burst in 1- and 2-year-old seedlings of nine provenances of Norway spruce (Picea abies (L.) Karst.). High temperature during dormancy induction, little or no chilling and low temperature during forcing all delayed dormancy release but did not prevent bud burst or growth onset provided the seedlings were forced under long-day conditions. Without chilling, bud burst occurred in about 20% of seedlings kept in short days at 12 degrees C, indicating that young Norway spruce seedlings do not exhibit true bud dormancy. Chilling hastened bud burst and removed the long photoperiod requirement, but the effect of high temperature applied during dormancy induction was observed even after prolonged chilling. Extension of the short-day treatment from 4 to 8 or 12 weeks hastened bud burst. The effect of treatments applied during dormancy development was larger than that of provenance; in some cases no provenance effect was detected, but in 1-year-old seedlings, time to bud burst decreased linearly with increasing latitude of origin. Differences among provenances were complicated by different responses of some origins to light conditions under long-day forcing. In conclusion, timing of bud burst in Norway spruce seedlings is significantly affected by temperature during bud set, and these effects are modified by chilling and environmental conditions during forcing.
深入了解温度对休眠发育和芽萌发时间的影响，将有助于评估气候变化对林木的影响。我们测试了短日照处理期间施加的温度、短日照处理的持续时间、低温处理的持续时间以及催芽期间的光照条件对挪威云杉（Picea abies (L.) Karst.）9个种源1年生和2年生幼苗芽萌发时间的影响。休眠诱导期间的高温、极少或没有低温处理以及催芽期间的低温都会延迟休眠解除，但只要幼苗在长日照条件下催芽，就不会阻止芽萌发或生长开始。在没有低温处理的情况下，约20%保持在12摄氏度短日照条件下的幼苗会出现芽萌发，这表明挪威云杉幼苗不表现出真正的芽休眠。低温处理加速了芽萌发并消除了对长光周期的需求，但即使经过长时间的低温处理，仍能观察到休眠诱导期间高温的影响。将短日照处理从4周延长至8周或12周会加速芽萌发。休眠发育期间施加的处理的影响大于种源的影响；在某些情况下未检测到种源效应，但在1年生幼苗中，芽萌发时间随起源纬度的增加呈线性下降。由于一些种源在长日照催芽条件下对光照条件的反应不同，种源间的差异变得复杂。总之，挪威云杉幼苗的芽萌发时间受芽形成期间温度的显著影响，这些影响会因催芽期间的低温处理和环境条件而改变。
