Silver nanoparticles intensify the allelopathic intensity of four invasive plant species in the Asteraceae

Abstract

This study aimed to estimate the allelopathic intensity of four Asteraceae invasive plant species (IPS), including Conyza canadensis (L.) Cronq., Erigeron annuus (L.) Pers., Bidens pilosa (L.), and Aster subulatus Michx., by testing the effect of leaf extracts on the seed germination and seedling growth (SGe and SGr) of lettuce (Lactuca sativa L.) in combination with two particle sizes of silver nanoparticles. These four IPS decreased the germination of lettuce seeds but increased the growth of lettuce seedlings. The allelopathic intensity of the four IPS decreased in the following order: B. pilosa > C. canadensis > E. annuus > A. subulatus. Silver nanoparticles decreased the SGe and SGr of lettuce. The 20 nm silver nanoparticles affected the competition intensity for water and the absorption of inorganic salts by lettuce more intensively than the 80 nm nanoparticles. Silver nanoparticles intensify the allelopathic intensity of the four invasive plant species on the SGe and SGr of lettuce. The allelopathic intensity of B.pilosa was higher than that of the other three IPS when they were polluted with silver nanoparticles. Thus, silver nanoparticles could facilitate the invasion process of the four IPS, particularly B. pilosa, via an increase in the intensity of allelopathy.

Does Salt Stress Intensify the Allelopathic Effect of Four Asteraceae Invasive Plants?

“…The consequences have confirmed the correctness of the Stress Hypothesis of Allelopathy (Reigosa et al 2002). Similarly, numerous results have confirmed that the adverse situation can intensify the allelopathy of invasive plants (Chavoushi et al 2020, Yu et al 2022a, Yu et al 2023, Zhong et al 2023b). Thus, the increased level of salt stress may be beneficial for the invasion of the studied four Asteraceae invasive species (especially S. canadensis ) typically via increased allelopathy of those species on the Seger-Segro of neighboring plant species.…”

“…In addition, 0.5 mL of deionized water, the leaf extracts of the studied invasive species, and/or salt solution were added to each Petri dish every day. The number of the normal germinated seeds of L. sativa was confirmed daily for all the Petri dishes throughout the incubation period, and a seed was confirmed as germinated when its radicle had germinated (Yu et al 2022a, Xu et al 2023b, Yu et al 2023, Zhong et al 2023b).…”