The Cerrado is a Neotropical savanna where grasses are a major biomass component in the open vegetation physiognomies. Invasive grasses are widely used as pastures in the Cerrado, and their presence may displace native species. The persistence of native grasses relies also on reproduction via seeds, which is often dependent on seeds found buried in the soil seed bank. The literature about the effects of light availability on the germination of Neotropical savanna grasses is scarce, and germination may lead to abnormal seedlings that develop only the root or the shoot. Germination trials that overlook this fact may overestimate the potential for seedling recruitment. Therefore, we tested the effects of light availability on the germination of nine native and two invasive grasses, addressing the production of normal seedlings. Seeds were germinated in the complete absence or the presence of light (12 h photoperiod under white light) for 30 days. Germination was defined as the sum of normal and abnormal seedlings. Eight species were light-dependent, decreasing the production of normal seedlings in the dark. Two native and one invasive species were non-responsive to the dark treatment, showing no change in germination or production of normal seedlings. Our results suggest that seeds buried in the soil seed bank are likely to show reduced germination and develop abnormal seedlings, reinforcing a bottleneck for the recruitment of native grasses. For invasive species, however, the potential of seedling recruitment was minimally reduced by light, suggesting a competitive advantage for the recruitment of these species.

中文翻译：

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光照影响新热带稀树草原的萌发和幼苗正常发育

塞拉多是一个新热带稀树草原，其中草是开放植被地貌中的主要生物量成分。入侵草在塞拉多被广泛用作牧场，它们的存在可能会取代本地物种。原生草的持久性还依赖于通过种子繁殖，这通常依赖于埋在土壤种子库中的种子。关于光照对新热带稀树草原萌发影响的文献很少，萌发可能导致异常幼苗仅发育根或芽。忽视这一事实的发芽试验可能高估了幼苗补充的潜力。因此，我们测试了光照对九种原生草和两种入侵草发芽的影响，解决了正常幼苗的生产问题。种子在完全不存在或存在光（白光下 12 小时光周期）下发芽 30 天。发芽被定义为正常和异常幼苗的总和。八个物种依赖光，在黑暗中减少了正常幼苗的产量。两种本地物种和一种入侵物种对暗处理没有反应，显示正常幼苗的发芽或生产没有变化。我们的研究结果表明，埋在土壤种子库中的种子很可能会减少发芽并产生异常幼苗，从而加剧了本地草的招募瓶颈。然而，对于入侵物种，幼苗招募的潜力因光照而降低了最低限度，这表明这些物种的招募具有竞争优势。