ABSTRACT The cerrado is a Neotropical savanna characterized by a soil and vegetation mosaic where plants endure dystrophic soils and seasonal drought. Dry spells or flooding are the main environmental stress native species face in their growth period. African grasses are common invasive species, jeopardizing the biodiversity by displacing native species and outgrowing them. Invasive species may benefit from human interventions that increase nutrient availability in natural areas and may respond differently than natives to environmental conditions. Therefore, we compared the performance of one native (Schizachyrium microstachyum) and one invasive (Melinis minutiflora) grass in different conditions of water and nutrient availability simulating possible cerrado scenarios. Five-week-old seedlings were submitted to different irrigation treatments (simulating dry spells, normal rainfall, and flooding) and fertilization treatments (high or low nutrient availability) for four weeks, and were analyzed for morphological (leaf area, length of the shoot, number of tillers, seedling dry weight, and root:shoot ratio) and physiological parameters (chlorophyll fluorescence, pigment concentration, nutrient content, and biochemical assays). There was a trend for the invasive species to show better responses to water stress by growing more profusely, showing an even higher effect when the soil was richer in nutrients. The invasive species may outcompete the native species by using nutrients and water more efficiently, showing a weaker oxidative response to drought and fertilization. The native species would perform at a similar pace to the invasive species in conditions of less water and nutrient availability, whereas unnatural fertilization inputs and high-water availability would benefit the invasive species.

中文翻译：

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水和养分有效性对新热带稀树草原的一种入侵草和一种原生草的形态、生理和生化特性的影响

摘要塞拉多是一种新热带稀树草原，其特征是土壤和植被镶嵌在一起，植物在那里忍受营养不良的土壤和季节性干旱。干旱期或洪水是本地物种在其生长期面临的主要环境压力。非洲草是常见的入侵物种，通过取代本地物种并使其生长过度而危及生物多样性。入侵物种可能受益于人类干预，这些干预增加了自然区域的养分供应，并且对环境条件的反应可能与本地物种不同。因此，我们比较了一种本地草（Schizachyrium microstachyum）和一种入侵草（Melinis minutiflora）在不同水和养分可用性条件下模拟可能的cerrado场景的性能。五周龄的幼苗接受不同的灌溉处理（模拟干旱期、正常降雨和洪水）和施肥处理（高或低养分利用率）4 周，并分析形态（叶面积、枝条长度） 、分蘖数、幼苗干重和根：芽比）和生理参数（叶绿素荧光、色素浓度、营养成分和生化分析）。入侵物种有一种趋势，即通过更大量地生长，对水分胁迫表现出更好的反应，当土壤中的养分更丰富时，表现出更高的影响。入侵物种可能通过更有效地利用养分和水来超越本地物种，对干旱和施肥表现出较弱的氧化反应。