Abstract Saltwater intrusion (SWI) is the landward movement of seawater, which can salinize coastal farmlands and affect crop yields. Germination is an especially vulnerable life history stage for crops. Salt stress reduces a seed’s ability to absorb water (osmotic stress) and causes an ion imbalance within the seed (ionic stress), ultimately inhibiting germination and preventing crop production. Therefore, growing standard crops in the face of SWI can risk crop failure. If alternative crops are more tolerant of osmotic and ionic stress, they may be more suited to withstand SWI. Our objectives were to (1) determine how salt stress (ionic and osmotic stress) and osmotic stress levels affect seed germination in standard and alternative crops in a controlled environment experiment and (2) compare germination rates in the controlled environment with field trials. In our study region of the Eastern Shore of Maryland, standard crop species include corn, soybean, and wheat; alternative species and varieties include sorghum, chloride-excluding soybean, barley, and quinoa. Seeds of these species were germinated under different levels of salt and osmotic stress ranging from 0 to −4 MPa (0–111.1 dS m−1, respectively) by manipulating concentrations of NaCl to alter salt stress and concentrations of polyethylene glycol to alter osmotic stress. Crop species differed greatly in germination tolerance to salt and osmotic stresses, however, there was no significant difference in percent germination between standard and alternative crop species. Standard soybean, chloride-excluding soybean, and quinoa were the only species to germinate in salt stress; standard soybean and chloride-excluding soybean had an equal tolerance during germination at -1.8 MPa (50.0 dS m−1) and quinoa successfully germinated at -0.5 MPa (13.9 dS m−1). However, wheat (standard) and barley (alternative) were the most tolerant of osmotic stress, successfully germinating at -2 MPa (55.6 dS m−1). We also examined germination of sorghum and chloride-excluding soybeans in previously-established field trials for two years on two salt-intruded farms on the Eastern Shore of Maryland. One of the farms showed greater germination success (measured as seedling emergence) in chloride-excluding soybean than sorghum despite a small difference in salt stress (Δ -0.05 MPa across the field). These results highlight the complexity of understanding how salt stress shapes germination processes in the real world and suggest temporal windows of low and high stress may have long-lasting consequences for crop performance.

中文翻译：

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海水入侵对标准作物和替代作物发芽成功的影响

摘要 海水入侵（SWI）是海水向陆上移动，使沿海农田盐渍化并影响作物产量。发芽是作物特别脆弱的生命史阶段。盐胁迫会降低种子吸收水分的能力（渗透胁迫）并导致种子内的离子失衡（离子胁迫），最终抑制发芽并阻止作物生产。因此，面对 SWI 种植标准作物可能会导致作物歉收。如果替代作物更能耐受渗透和离子压力，它们可能更适合承受 SWI。我们的目标是 (1) 确定盐胁迫（离子胁迫和渗透胁迫）和渗透胁迫水平如何在受控环境试验中影响标准作物和替代作物的种子发芽，以及 (2) 将受控环境中的发芽率与田间试验进行比较。在我们研究的马里兰州东岸地区，标准作物种类包括玉米、大豆和小麦；替代物种和品种包括高粱、不含氯化物的大豆、大麦和藜麦。这些物种的种子在 0 到 -4 MPa（分别为 0-111.1 dS m-1）的不同盐分和渗透胁迫下发芽，方法是通过控制 NaCl 浓度来改变盐胁迫和聚乙二醇浓度来改变渗透胁迫. 作物品种对盐和渗透胁迫的萌发耐受性差异很大，然而，标准作物品种和替代作物品种之间的发芽百分比没有显着差异。标准大豆、不含氯化物的大豆和藜麦是仅有的在盐胁迫下发芽的物种；标准大豆和不含氯化物的大豆在 -1.8 MPa (50.0 dS m-1) 的发芽过程中具有相同的耐受性，而藜麦在 -0.5 MPa (13.9 dS m-1) 下成功发芽。然而，小麦（标准）和大麦（替代）对渗透胁迫最耐受，在 -2 MPa (55.6 dS m-1) 下成功发芽。我们还在马里兰州东海岸的两个盐渍化农场进行了为期两年的田间试验，研究了高粱和不含氯化物的大豆的发芽情况。尽管盐胁迫差异很小（整个田间的Δ -0.05 MPa），但其中一个农场在不含氯化物的大豆中表现出比高粱更高的发芽成功率（以幼苗出苗衡量）。这些结果突出了理解盐胁迫如何影响现实世界中的发芽过程的复杂性，并表明低和高压力的时间窗口可能对作物性能产生长期影响。