Functional traits of seeds reflect plant reproductive strategies adapting to environmental changes, which is an evolutionary behavior in natural selection and genetics. Study on seed functional traits is of great significance to deeply understand the long-term adaptive evolution of plants and seeds. We measured seed functional traits of a main indigenous species Phragmites australis, including seed size, seed weight, seed set, and seed production, in nine coastal marshes of the six provinces/cities along the coastal zone of China (21°29'-40°57' N), and analyzed latitudinal variations of functional traits. The results showed that seed functional traits of P. australis in Chinese coastal marshes varied significantly with latitude and that there were significant correlations among different traits. Seed size (including seed length, seed width, seed shape index, aspect ratio, and seed surface area), and 100-seed weight showed significant quadratic function relation with latitude, which firstly decreased and then increased with the increases of latitude, while seed setting rate firstly increased and then reduced. There was a trade-off between the number and size of P. australis seeds. Seed production per unit area significantly increased with latitude. Results of stepwise regression analysis showed that climatic factors were the main driver resulting in the difference of seed functional traits of P. australis between latitudes, followed by pH and salinity of soil porewater.
种子功能性状反映了植物适应环境变化的繁殖对策,这是植物在自然环境选择和遗传上的一种进化行为,对深入认识植物及种子对环境的长期适应性进化意义重大。本研究对中国滨海6个省市9个地区的滨海沼泽湿地(21°29′—40°57′ N)主要土著植物芦苇种子功能性状(包括种子大小、重量、结实率和产量)进行研究,分析其纬度变异规律。结果表明: 我国滨海湿地芦苇种子各功能性状在不同纬度差异显著,各功能性状间具有显著的相关性。芦苇种子大小(种长、种宽、种形指数、长宽比、种子表面积)和百粒重与纬度呈显著的二次函数关系,随着纬度升高先降后升,而种子结实率呈现先升后降的规律,芦苇种子数量与大小间存在着权衡关系。单位面积种子产量随着纬度升高显著增加。逐步回归分析显示,气候因素是影响不同纬度间芦苇种子功能性状差异的主要因素,土壤孔隙水的pH和盐度次之。.
Keywords: Phragmites australis; coastal marsh; latitude; seed functional trait.