The Australian PlantBank, Australian Institute of Botanical Science, Australian Botanic Garden, Mount Annan, NSW 2567, Australia.
Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, Sydney NSW 2052, Australia.
Ann Bot. 2022 Jul 18;129(7):787-794. doi: 10.1093/aob/mcac026.
Seed germination is strongly influenced by environmental temperatures. With global temperatures predicted to rise, the timing of germination for thousands of plant species could change, leading to potential decreases in fitness and ecosystem-wide impacts. The thermogradient plate (TGP) is a powerful but underutilized research tool that tests germination under a broad range of constant and alternating temperatures, giving researchers the ability to predict germination characteristics using current and future climates. Previously, limitations surrounding experimental design and data analysis methods have discouraged its use in seed biology research.
Here, we have developed a freely available R script that uses TGP data to analyse seed germination responses to temperature. We illustrate this analysis framework using three example species: Wollemia nobilis, Callitris baileyi and Alectryon subdentatus. The script generates >40 germination indices including germination rates and final germination across each cell of the TGP. These indices are then used to populate generalized additive models and predict germination under current and future monthly maximum and minimum temperatures anywhere on the globe.
In our study species, modelled data were highly correlated with observed data, allowing confident predictions of monthly germination patterns for current and future climates. Wollemia nobilis germinated across a broad range of temperatures and was relatively unaffected by predicted future temperatures. In contrast, C. baileyi and A. subdentatus showed strong seasonal temperature responses, and the timing for peak germination was predicted to shift seasonally under future temperatures.
Our experimental workflow is a leap forward in the analysis of TGP experiments, increasing its many potential benefits, thereby improving research predictions and providing substantial information to inform management and conservation of plant species globally.
种子的萌发受到环境温度的强烈影响。随着全球气温的预测上升，数千种植物物种的萌发时间可能会发生变化，从而导致适应能力下降和对生态系统的广泛影响。温梯板（TGP）是一种强大但未被充分利用的研究工具，它可以在广泛的恒定和交替温度下测试种子的萌发，使研究人员能够使用当前和未来的气候来预测萌发特性。以前，实验设计和数据分析方法的限制阻碍了它在种子生物学研究中的应用。
在这里，我们开发了一个免费的 R 脚本，该脚本使用 TGP 数据来分析种子对温度的萌发反应。我们使用三个示例物种：Wollemia nobilis、Callitris baileyi 和 Alectryon subdentatus 来说明这种分析框架。该脚本生成了超过 40 个萌发指数，包括每个 TGP 单元的萌发率和最终萌发率。然后，这些指数用于填充广义加性模型，并预测全球任何地方当前和未来每月最高和最低温度下的萌发情况。
在我们的研究物种中，模型数据与观察数据高度相关，允许对当前和未来气候下的每月萌发模式进行有信心的预测。Wollemia nobilis 在广泛的温度范围内萌发，并且受预测未来温度的影响相对较小。相比之下，C. baileyi 和 A. subdentatus 表现出强烈的季节性温度响应，并且预计在未来温度下，峰值萌发的时间将季节性转移。
我们的实验工作流程是 TGP 实验分析的一大进步，增加了它的许多潜在好处，从而提高了研究预测，并提供了大量信息，以指导全球植物物种的管理和保护。
