Probert Robin J, Daws Matthew I, Hay Fiona R
Seed Conservation Department, Royal Botanic Gardens Kew, Ardingly, West Sussex, UK.
Ann Bot. 2009 Jul;104(1):57-69. doi: 10.1093/aob/mcp082. Epub 2009 Apr 9.
Extended seed longevity in the dry state is the basis for the ex situ conservation of 'orthodox' seeds. However, even under identical storage conditions there is wide variation in seed life-span between species. Here, the effects of seed traits and environmental conditions at the site of collection on seed longevity is explored for195 wild species from 71 families from environments ranging from cold deserts to tropical forests.
Seeds were rapidly aged at elevated temperature and relative humidity (either 45 degrees C and 60% RH or 60 degrees C and 60% RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50% (p(50)) was determined using Probit analysis and used as a measure of relative seed longevity between species.
Across species, p(50) at 45 degrees C and 60% RH varied from 0.1 d to 771 d. Endospermic seeds were, in general, shorter lived than non-endospermic seeds and seeds from hot, dry environments were longer lived than those from cool, wet conditions. These relationships remained significant when controlling for the effects of phylogenetic relatedness using phylogenetically independent contrasts. Seed mass and oil content were not correlated with p(50).
The data suggest that the endospermic seeds of early angiosperms which evolved in forest understorey habitats are short-lived. Extended longevity presumably evolved as a response to climatic change or the invasion of drier areas. The apparent short-lived nature of endospermic seeds from cool wet environments may have implications for re-collection and re-testing strategies in ex situ conservation.
干燥状态下种子较长的寿命是“正统”种子迁地保护的基础。然而，即使在相同的储存条件下，不同物种的种子寿命仍存在很大差异。本文针对来自71个科的195种野生植物种子，研究了种子特性和采集地环境条件对种子寿命的影响，这些植物分布于从寒冷沙漠到热带森林的各种环境中。
将种子在高温高湿条件下（45℃、相对湿度60%或60℃、相对湿度60%）快速老化，并定期取样检测发芽率。采用概率分析确定种子活力降至50%（p(50)）所需的储存时间，并以此作为衡量不同物种间相对种子寿命的指标。
在所有物种中，45℃、相对湿度60%条件下的p(50)从0.1天到771天不等。一般来说，有胚乳种子的寿命比无胚乳种子短，来自炎热干燥环境的种子比来自凉爽湿润环境的种子寿命长。在使用系统发育独立对比法控制系统发育相关性的影响后，这些关系仍然显著。种子质量和含油量与p(50)无关。
数据表明，早期在森林林下栖息地进化的被子植物的有胚乳种子寿命较短。种子寿命的延长可能是对气候变化或干旱地区入侵的一种响应。凉爽湿润环境中有胚乳种子明显较短的寿命可能对迁地保护中的重新采集和重新测试策略有影响。
