Seed dormancy types and germination response of 15 plant species in temperate montane peatlands

Despite their crucial role in determining the fate of seeds, the type and
breaking mode of seed dormancy in peatland plants in temperate Asia with a
continental monsoon climate are rarely known. Fifteen common peatland
plant species were used to test their seed germination response to various
dormancy-breaking treatments, including dry storage (D), gibberellin acid
soaking (GA), cold stratification (CS), warm followed cold stratification
(WCS), GA soaking + cold stratification (GA+CS) and GA soaking + warm
followed cold stratification (GA+WCS). Germination experiment, viability
and imbibition test, and morphological observation of embryos were
conducted. Of the 15 species, nine showed physiological dormancy (PD),
with non-deep PD being the dominant type. Four species, Angelica
pubescens, Cicuta virosa, Iris laevigata and Iris setosa exhibited
morphological physiological dormancy. Two species, Lycopus uniflorus and
Spiraea salicifolia, demonstrated non-dormancy of seeds. Overall, the
effect hierarchy of dormancy-breaking is: CS > GA > WCS
> GA+CS > D > GA+WCS. Principal component analysis
demonstrated that seed traits, including embryo length: seed length ratio,
seed size, and monocot/eudicot divergence, are more likely to influence
seed dormancy than environmental factors. Our study suggests that nearly
90% of the tested peatland plant species in the Changbai Mountains
demonstrated seed dormancy, and seed traits (e.g. embryo to seed ratio and
seed size) and abiotic environmental factors (e.g. pH and temperature
seasonality) are related to germination behavior, suggesting seed dormancy
being a common adaptation strategy for the peatland plants in the
temperate montane environment.

尽管种子休眠对决定种子命运起着至关重要的作用，但具有大陆性季风气候的亚洲温带泥炭地植物，其种子休眠类型与破除方式却鲜为人知。本研究选取15种常见泥炭地植物，探究其种子萌发对多种休眠破除处理的响应，处理方式包括干藏（dry storage, D）、赤霉素浸种（gibberellin acid soaking, GA）、低温层积（cold stratification, CS）、先暖温后低温层积（warm followed cold stratification, WCS）、赤霉素浸种+低温层积（GA soaking + cold stratification, GA+CS）以及赤霉素浸种+先暖温后低温层积（GA soaking + warm followed cold stratification, GA+WCS）。本研究开展了种子萌发实验、种子活力与吸胀试验以及胚胎形态学观察。在所测试的15个物种中，9个表现出生理休眠（physiological dormancy, PD），其中非深度生理休眠为优势类型。另有4个物种——Angelica pubescens、Cicuta virosa、Iris laevigata与Iris setosa——表现出形态生理休眠。剩余2个物种Lycopus uniflorus和Spiraea salicifolia的种子无休眠特性。总体而言，各休眠破除处理的效应排序为：CS＞GA＞WCS＞GA+CS＞D＞GA+WCS。主成分分析结果显示，相较于环境因子，种子性状（包括胚长/种子长比值、种子大小以及单子叶/真双子叶植物分化）对种子休眠的影响更为显著。本研究表明，长白山温带泥炭地中近90%的受试泥炭地植物物种存在种子休眠现象；种子性状（如胚种比、种子大小）与非生物环境因子（如pH值、温度季节性变化）均与种子萌发行为相关，这说明种子休眠是温带山地环境中泥炭地植物的一种普遍适应策略。