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 Na
2SO
4 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 Na
2SO
4 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 Na
2SO
4 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.