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盐胁迫下盐地碱蓬种子萌发及早期幼苗生长对互花米草化感作用的响应

Responses of seed germination and early seedling growth of Suaeda salsa to allelopathy of Spartina alterniflora under salt stress

  • 摘要: 为了了解互花米草(Spartina alterniflora)入侵导致黄河三角洲盐地碱蓬(Suaeda salsa)群落退化的作用机制,从化感作用角度研究了互花米草地上、地下部分浸提液及不同盐处理对盐地碱蓬种子萌发及早期幼苗生长的影响。采用种子发芽床法,测定了盐地碱蓬种子萌发率、萌发速度、幼苗胚根长、生物量等指标。研究结果表明,不同浓度互花米草地上和地下部分浸提液对盐地碱蓬种子萌发及幼苗生长具有化感作用。低浓度Na2SO4和NaCl (<100 mmol/L)处理下,50.00 g/L浓度的互花米草不同部位浸提液均显著降低了盐地碱蓬种子的萌发率和萌发速度。随着盐浓度的升高,互花米草不同部位浸提液对盐地碱蓬种子萌发的化感抑制作用减弱。500 mmol/L Na2SO4处理下,50.00 g/L浓度的互花米草地上和地下部分浸提液对盐地碱蓬种子萌发率和萌发速度均产生了一定的促进作用。100 mmol/L NaCl促进了盐地碱蓬胚根的生长,但与对照组相比,6.25 g/L和50.00 g/L浓度的互花米草浸提液均对盐地碱蓬幼苗胚根生长产生了显著的抑制作用。与萌发率相似,500 mmol/L Na2SO4处理下,50.00 g/L浓度互花米草浸提液促进了盐地碱蓬胚根的生长。有趣的是,盐地碱蓬幼苗生物量呈现相反的趋势,当盐浓度低于300 mmol/L时,互花米草浸提液对盐地碱蓬幼苗的生物量积累产生了一定的促进作用。可见,互花米草浸提液能够显著抑制盐地碱蓬种子萌发,同时又能够为盐地碱蓬幼苗生物量的积累提供一定的营养物质,该研究结果从化感作用角度为探究滨海湿地互花米草入侵盐地碱蓬群落的机制提供了不同的视角。

     

    Abstract: To better understand the mechanisms by which the invasion of Spartina alterniflora leads to the degradation of Suaeda salsa communities in the saline lands of the Yellow River Delta, this study focused on the allelopathic effects of S. alterniflora. Specifically, the impact of leachates from both the aerial and underground parts of S. alterniflora as well as different salinity treatments on seed germination and early seedling growth of S. salsa was examined. A seed germination bed method was employed, and several key indicators were measured, including seed germination rate, germination speed, root length, and biomass of the seedlings. The results showed that leachates from various parts of S. alterniflora, at different concentrations, exerted significant allelopathic effects on the seed germination and early growth of S. salsa. When treated with low concentrations of Na2SO4 and NaCl (<100 mmol/L), leachates from both the aerial and underground parts of S. alterniflora significantly inhibited the seed germination rate and germination speed of S. salsa. However, as the salinity concentration increased, the allelopathic inhibitory effects of the leachates from S. alterniflora on S. salsa seed germination decreased. Under the 500 mmol/L Na2SO4 treatment, leachates from both the aerial and underground parts of S. alterniflora at a concentration of 50.00 g/L promoted seed germination rate and speed, suggesting a potential alleviating effect under higher salinity conditions. Moreover, a 100 mmol/L NaCl treatment was found to promote the growth of the roots of S. salsa seedlings. In contrast, leachates from S. alterniflora at concentrations of 6.25 g/L and 50.00 g/L significantly inhibited seedling root growth compared to the control group. This finding parallels the seed germination data, where leachates under the 500 mmol/L Na2SO4 treatment at a concentration of 50.00 g/L promoted the growth of seedling roots, further confirming the complex interactions between salinity levels and allelopathic effects. Interestingly, the biomass of S. salsa seedlings showed an inverse trend: when the salinity concentration was below 300 mmol/L, leachates from S. alterniflora promoted the accumulation of biomass in S. salsa seedlings, suggesting a potential compensatory mechanism. The study highlights that while leachates from S. alterniflora significantly inhibit seed germination of S. salsa, they may simultaneously provide essential nutrients that promote the growth and biomass accumulation of S. salsa seedlings, particularly under certain salinity conditions. These results, from an allelopathic perspective, offer new insights into the mechanisms by which the invasion of S. alterniflora affects coastal wetland S. salsa communities, providing valuable information for understanding the ecological dynamics and managing invasive species in coastal ecosystems.

     

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