Reproductive phenology and germination of Eleocharis laeviglumis R. Trevis. & Boldrini (Cyperaceae)

ABSTRACT Aquatic macrophytes are important components of freshwater ecosystems, of which Cyperaceae is the most diverse family. Many species of Cyperaceae form dense populations along lake margins of the southern coast of Brazil, but little is known about their sexual reproductive strategies. We characterized the reproductive life cycle of Eleocharis laeviglumis, an abundant emergent macrophyte of coastal wetlands in southern Brazil, by assessing its reproductive phenophases and estimating the number of its flowers and potentially viable fruits per inflorescence in a natural population. We also tested seed germinability and vigor for a period of four months during a single reproductive season. The species possesses dichogamous and protogynous spikelets with an average duration of 34 days (pre-anthesis, 1.7 d; anthesis, 6.9 d; fruit maturation, 22.3 d; fruit dispersion, 3.2 d). More than half of the flowers (62.2 %) developed into fruits, while only 5.5 % of the seeds germinated. Germinability and vigor decreased during the reproductive season. Some culms probably originate from asexual reproduction or sexual reproduction of clones. For restoration purposes, we suggest that E. laeviglumis should be propagated by sowing seeds collected at the beginning of the reproductive season, along with the transplantation of rhizomes.

摘要 水生大型植物是淡水生态系统的重要组成部分，其中莎草科（Cyperaceae）是物种多样性最高的类群。巴西南部沿岸湖岸带分布有大量莎草科物种形成的密集种群，但学界对其有性生殖策略的了解仍较为匮乏。本研究以巴西南部滨海湿地中常见的优势挺水大型植物光鳞荸荠（Eleocharis laeviglumis）为研究对象，通过调查其自然种群的生殖物候期，并估算每花序的花朵数与潜在可育果实数，明确了该物种的生殖生活周期。此外，本研究还在单个生殖季内开展了为期四个月的种子萌发能力与活力测定。该物种的小穗为雌雄异熟且雌性先熟类型，平均持续时长为34天（开花前期1.7天、开花期6.9天、果实成熟期22.3天、果实扩散期3.2天）。超过半数的花朵（62.2%）可发育为果实，但仅5.5%的种子能够萌发。生殖季内，种子的萌发能力与活力呈逐步下降趋势。部分秆茎可能源自无性繁殖，或来自克隆株的有性繁殖。出于生态修复目的，我们建议通过播种生殖季初期采集的种子，并配合根茎移栽的方式繁殖该物种。