Can allelopathy of extracts aggravate the effects of salt stress on the seed germination of ?

is highly adaptable with high competitive ability and is widely distributed in the coastal wetland of the Yellow River Delta. However, allelopathic effects of on the growth of neighboring plants, such as , are poorly understood. In this study, germination responses of seeds collected from two different habitats (intertidal zone and inland brackish wetland) to the extracts from different part of were compared. Potential allelopathic effects on germination percentage, germination rate, radicle length, and seedling biomass were analyzed. The germination of was effectively inhibited by extract. Extract organ, extract concentration, and salt concentration showed different effects, the inhibitory rates were highest with belowground extract of between the four different parts. Germination percentage and germination rate were significantly decreased by the interactive effect of salt stress and extract concentration in from a brackish wetland but not in from the intertidal zone. The impact of different extracts of on radicle length and seedling biomass of showed significant but inconsistent variation. The response index results showed that the higher concentration of extract solution (50 g·L) of had stronger inhibitory effect on the seed germination and seedling growth of while the belowground extract had the strongest negative effect. Our results indicated that allelopathy is an important ecological adaptation mechanism for to maintain a high interspecific competitive advantage in the species' natural habitat.