Abstract Water availability during seed germination and seedling development is critical to plant development and establishment. The aim of this study was to determine the effects of four water potentials (ΨW) (−0.03, −0.48, −1.19 and −2.04 MPa) on seed germination, seedling root growth and root membrane stability of Agave lechuguilla Torr. and A. salmiana Otto ex Salm-Dyck. to explain the paradoxical situation of vegetatively propagated species producing large quantities of seeds in a dry climate. The results showed that seed water uptake and germination percentage were significantly lower at −1.19 and −2.04 MPa than at −0.03 MPa. The time to reach maximum seed germination increased at low ΨW. The final root length and root growth rate were higher in A. salmiana than in A. lechuguilla and decreased at ΨW of −1.19 and −2.04 MPa. Both Agave species increased root electrolyte leakage at ΨW of −1.19 MPa, which suggests changes in membrane integrity and stability in response to the water deficit. These germination and initial root growth responses could ensure the establishment of both Agave species during the rare periods with sufficient moisture availability and allow them to tolerate initial periods of low water availability, although with low establishment probability.

中文翻译：

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水分有效性对龙舌兰 lechuguilla 和 A. salmiana 的萌发、膜稳定性和初始根生长的影响

摘要 种子萌发和幼苗发育过程中的水分供应对植物发育和建立至关重要。本研究的目的是确定四种水势 (ΨW)（-0.03、-0.48、-1.19 和 -2.04 MPa）对龙舌兰种子萌发、幼苗根生长和根膜稳定性的影响。和 A. salmiana Otto ex Salm-Dyck。解释无性繁殖物种在干燥气候下产生大量种子的矛盾情况。结果表明，-1.19 和-2.04 MPa 的种子吸水率和发芽率显着低于-0.03 MPa。达到最大种子发芽的时间在低 ΨW 时增加。A. salmiana 的最终根长和根生长速率高于 A. lechuguilla，并在 ΨW 为 -1.19 和 -2.04 MPa 时降低。在 ΨW 为 -1.19 MPa 时，两种龙舌兰物种都增加了根部电解质泄漏，这表明膜完整性和稳定性会随着水分不足而发生变化。这些发芽和初始根生长反应可以确保在稀有时期建立两种龙舌兰物种，并具有足够的水分可用性，并允许它们耐受初始水分可用性低的时期，尽管建立概率较低。