Salinity can compromise the growth of aquatic macrophytes, influencing their nutrient content and interspecific interactions. In estuaries, the sediment characteristics vary in salinity as well as nutrient availability, granulometry and microbiota. The use of artificial substrates in manipulative experiments allows the evaluation of the isolated effect of salinity on plants. We evaluated the effects of salinity on growth, interspecific interaction and total nitrogen (TN) content of the estuarine macrophytes Spartina alterniflora and Crinum americanum cultivated on expanded vermiculite. We conducted a two-factor experiment (3 cultures × 3 salinities × 5 replicates = 45 experimental units) lasting 185 days in a greenhouse. We cultivated monocultures (8:0 and 0:8) and mixed cultures (4:4) at 0, 20 and 30 ppt salinity levels with the same concentration of nutrient solution. We found that salinity did not influence the growth of S. alterniflora and C. americanum in monoculture. In mixed culture, there was an asymmetric competition, as S. alterniflora limited the growth of the aboveground fraction of C. americanum at higher salinity; however, C. americanum did not limit the growth of S. alterniflora at any treatment. Salinity did not influence the TN content in S. alterniflora. However, C. americanum had greater TN content in the aboveground fraction at higher salinity, possibly as a strategy of salt tolerance. The TN content in the aboveground fraction of C. americanum was lower in the mixed cultures than in the monocultures, indicating an effect of the interspecific interaction.

盐度会损害水生植物的生长，影响其营养成分和种间相互作用。在河口，沉积物特征在盐度，养分利用率，粒度和微生物区系方面有所不同。在操纵实验中使用人工基质可以评估盐度对植物的孤立作用。我们评估了盐度对河口大型植物互花米草和美洲垂枝木生长，种间相互作用和总氮（TN）含量的影响种植在膨胀的ver石上。我们在温室中进行了一项为期两天的实验（3个培养物×3盐度×5个重复样本= 45个实验单位），持续185天。我们在相同浓度的营养液下，分别在0、20和30 ppt的盐度水平下培养了单培养（8：0和0：8）和混合培养（4：4）。我们发现盐度不影响单一栽培中互花米草和美洲念珠菌的生长。在混合培养中，存在不对称竞争，因为互花米草在较高盐度下限制了美洲锥果地上部分的生长。但是，美洲念珠菌并没有限制互花米草的生长在任何治疗。盐度不影响互花米草中总氮的含量。但是，美洲锥。在较高盐度下地上部分的总氮含量更高，可能是作为耐盐策略。在混合培养中，美洲锥above地上部分中的TN含量低于单培养中的TN含量，表明种间相互作用的影响。