IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Av. San Martin 4453, Buenos Aires, Argentina.
Plant Biol (Stuttg). 2011 Jul;13(4):660-6. doi: 10.1111/j.1438-8677.2010.00417.x. Epub 2011 Feb 9.
Our aim was to search for specific seed germinative strategies related to flooding escape in Setaria parviflora, a common species across the Americas. For this purpose, we investigated induction after floods, in relation to fluctuating temperature requirements for germination in seeds from mountain, floodplain and successional grasslands. A laboratory experiment was conducted in which seeds were imbibed or immersed in water at 5°C. Seeds were also buried in flood-prone and upland grasslands and exhumed during the flooding season. Additionally, seeds were buried in flooded or drained grassland mesocosms. Germination of exhumed seeds was assayed at 25°C or at 20°C/30°C in the dark or in the presence of red light pulses. After submergence or soil flooding, a high fraction (>32%) of seeds from the floodplain required fluctuating temperatures to germinate. In contrast, seeds from the mountains showed maximum differences in germination between fluctuating and constant temperature treatment only after imbibition (35%) or in non-flooded soil conditions (40%). The fluctuating temperature requirement was not clearly related to the foregoing conditions in the successional grassland seeds. Maximum germination could also be attained with red light pulses to seeds from mountain and successional grasslands. Results show that the fluctuating temperature requirement might help floodplain seeds to germinate after floods, indicating a unique feature of the dormancy of S. parviflora seeds from floodplains, which suggests an adaptive advantage aimed at postponing emergence during inundation periods. In contrast, the fluctuating temperature required for germination among seeds from mountain and successional grasslands show its importance for gap detection.
我们的目的是寻找与谷子（Setaria parviflora）逃避水淹有关的特定种子萌发策略，谷子是美洲广泛分布的一种常见物种。为此，我们研究了洪水后的诱导作用，以及高山、洪泛平原和演替草地种子的萌发对温度波动的要求。进行了一项实验室实验，其中将种子在 5°C 下进行吸胀或浸泡。还将种子埋藏在洪水泛滥和高地草原中，并在洪水季节进行挖掘。此外，还将种子埋藏在淹没或排水的草原中进行实验。挖掘出的种子在 25°C 或 20°C/30°C 黑暗或红光脉冲下进行萌发测试。在淹没或土壤淹没后，来自洪泛平原的种子中有很大一部分（>32%）需要温度波动才能萌发。相比之下，来自山区的种子只有在吸胀（35%）或在未受洪水影响的土壤条件下（40%），才能在变温和恒温和处理之间显示出最大的萌发差异。变温需求与演替草地种子的上述条件之间没有明显的关系。来自山区和演替草地的种子也可以通过红光脉冲达到最大萌发率。结果表明，温度波动要求可能有助于洪泛平原种子在洪水后萌发，这表明了洪泛平原谷子种子休眠的一个独特特征，表明了一种适应性优势，旨在推迟淹没期间的出现。相比之下，来自山区和演替草地的种子的变温萌发要求表明了其对空隙检测的重要性。
