School of Ecology and Environment, Tibet University, Lhasa 850000, China.
Key Laboratory of Biodiversity and Environmental on the Qinghai-Tibetan Plateau, Ministry of Education, School of Ecology and Environment, Tibet University, Lhasa 850000, China.
Ann Bot. 2024 Aug 22;134(3):485-490. doi: 10.1093/aob/mcae086.
Some plants germinate their seeds enclosed by a pericarp, whereas others lack the outer packaging. As a maternal tissue, the pericarp might impart seeds with different germination strategies. Plants in a community with different flowering times might separately disperse and germinate their seeds; therefore, flowering time can be considered as one manifestation of maternal effects on the offspring. The mass of the seed is another important factor influencing germination and represents the intrinsic resource of the seed that supports germination. Using seeds from a species-rich alpine meadow located in the Hengduan Mountains of China, a global biodiversity hotspot, we aimed to illustrate whether and how the type of seed (with or without a pericarp) modulates the interaction of flowering time and seed mass with germination.
Seeds were germinated in generally favourable conditions, and the speed of germination [estimated by mean germination time (MGT)] was calculated. We quantified the maternal conditions by separation of flowering time for 67 species in the meadow, of which 31 produced seeds with pericarps and 36 yielded seeds without pericarps. We also weighed 100 seeds of each species to assess their mass.
The MGT varied between the two types of seeds. For seeds with pericarps, MGT was associated with flowering time but not with seed mass. Plants with earlier flowering times in the meadow exhibited more rapid seed germination. For seeds without a pericarp, the MGT depended on seed mass, with smaller seeds germinating more rapidly than larger seeds.
The distinct responses of germination to flowering time and seed mass observed in seeds with and without a pericarp suggest that germination strategies might be mother-reliant for seeds protected by pericarps but self-reliant for those without such protection. This new finding improves our understanding of seed germination by integrating ecologically mediated maternal conditions and inherent genetic properties.
有些植物的种子被果皮包裹着发芽，而有些植物则没有这种外部包装。作为一种母体组织，果皮可能会赋予种子不同的发芽策略。在一个具有不同开花时间的群落中的植物可能会分别分散和发芽它们的种子；因此，开花时间可以被认为是母体对后代的一种影响表现。种子的质量是另一个影响发芽的重要因素，代表了支持发芽的种子内在资源。使用来自中国横断山区一个物种丰富的高山草甸的种子，该地区是全球生物多样性热点地区，我们旨在说明种子的类型（有果皮或无果皮）是否以及如何调节开花时间和种子质量与发芽的相互作用。
种子在通常有利的条件下发芽，并计算发芽速度[用平均发芽时间（MGT）估计]。我们通过对草甸中 67 个物种的开花时间进行分离来量化母体条件，其中 31 个物种产生有果皮的种子，36 个物种产生无果皮的种子。我们还称取每个物种的 100 粒种子来评估其质量。
两种类型的种子的 MGT 不同。对于有果皮的种子，MGT 与开花时间有关，但与种子质量无关。草甸中开花时间较早的植物表现出更快的种子发芽速度。对于没有果皮的种子，MGT 取决于种子质量，较小的种子比较大的种子发芽更快。
有果皮和无果皮的种子对开花时间和种子质量的发芽反应明显不同，这表明对于受果皮保护的种子，发芽策略可能依赖于母体，而对于没有这种保护的种子，则依赖于自身。这一新发现通过整合生态介导的母体条件和内在遗传特性，提高了我们对种子发芽的理解。
