School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia, United States of America.
PLoS One. 2024 Jun 4;19(6):e0303638. doi: 10.1371/journal.pone.0303638. eCollection 2024.
Arthraxon hispidus is an introduced, rapidly spreading, and newly invasive grass in the eastern United States, yet little is known about the foundational biology of this aggressive invader. Germination responses to environmental factors including salinity, pH, osmotic potential, temperature, and burial depth were investigated to better understand its germination niche. Seeds from six populations in the Mid-Atlantic US germinated 95% with an average mean time to germination of 3.42 days of imbibition in the dark at 23°C. Germination occurred across a temperature range of 8-37°C and a pH range of 5-10 (≥83%), suggesting that neither pH nor temperature will limit germination in many environments. Arthraxon hispidus germination occurred in high salinity (342 mM NaCl) and osmotic potentials as low as -0.83MPa. The NaCl concentration required to reduce germination by 50% exceeded salinity concentrations found in soil and some brackish water saltmarsh systems. While drought adversely affects A. hispidus, 50% germination occurred at osmotic potentials ranging from -0.25 to -0.67 MPa. Given the climatic conditions of North America, drought stress is unlikely to restrict germination in large regions. Finally, emergence greatly decreased with burial depth. Emergence was reduced to 45% at 1-2 cm burial depths, and 0% at 8 cm. Emergence depths in concert with adequate moisture, germination across a range of temperatures, and rapid germination suggests A. hispidus' seed bank may be short-lived in moist environments, but further investigation is warranted. Given the broad abiotic tolerances of A. hispidus and a widespread native range, A. hispidus has the potential to germinate in novel territories beyond its currently observed invaded range.
糙叶薹草是一种引入美国东部的、快速传播的、新入侵的草本植物，但对这种具有侵略性的外来生物的基础生物学了解甚少。本研究调查了盐分、pH 值、渗透势、温度和埋藏深度等环境因子对萌发的影响，以更好地了解其萌发生态位。来自美国中大西洋地区的 6 个种群的种子在黑暗中于 23°C 下吸胀 3.42 天后，萌发率达到 95%。萌发发生在 8-37°C 的温度范围和 5-10（≥83%）的 pH 值范围内，这表明在许多环境中，pH 值和温度都不会限制其萌发。糙叶薹草的萌发发生在高盐度（342mM NaCl）和低至-0.83MPa 的渗透势下。将萌发率降低 50%所需的 NaCl 浓度超过了土壤和一些半咸水盐沼系统中发现的盐度浓度。尽管干旱对糙叶薹草有不利影响，但在渗透势为-0.25 至-0.67 MPa 的范围内，仍有 50%的种子萌发。鉴于北美的气候条件，干旱胁迫不太可能在大片地区限制其萌发。最后，埋藏深度对出苗率有很大影响。当埋藏深度为 1-2cm 时，出苗率降至 45%，当埋藏深度为 8cm 时，出苗率为 0%。与充足水分结合，在一定温度范围内迅速萌发表明，糙叶薹草的种子库在潮湿环境中可能寿命较短，但需要进一步研究。鉴于糙叶薹草广泛的生物耐性和分布范围，糙叶薹草有可能在其目前观察到的入侵范围之外的新领地中萌发。
