Does the salt stress intensify the independent allelopathy and the co-allelopathy of Solidago canadensis L. and Conyza canadensis (L.) Cronq.?

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

“…In general, salt stress can inhibit the growth performance of plants through water deficiency, ion ecotoxicity, and/or ion imbalance mediated by increased osmotic stress (Ghirardelli et al 2021, Huang et al 2021, Kumawat et al . 2022, Yu et al 2023). In this study, salt stress regardless of the concentration significantly decreased competitiveness for sunlight acquisition as well as competitiveness for water and inorganic salt acquisition of L. sativa (Fig.…”

“…The dried leaves of the studied invasive species were soaked in deionized water at ≈ 25°C for ≈ 2 d to obtain four aqueous leaf extracts, of each invasive plant species separately. The concentration of the aqueous leaf extracts was all set at 10 g/L (W (the dry weight of the leaves) /V) to simulate the conditions of allelopathy mediated by the studied Asteraceae invasive species (Lu et al 2020, Xu et al 2023b, Yu et al 2023, Zhong et al 2023b). The extracts were used within 7 days.…”

“…The salt solution was prepared using sodium chloride (NaCl; purity: ≥ 99.5%). The salt solution was adjusted to two concentrations: 25 mg/L (mimicking light salt stress) and 50 mg/L (mimicking heavy salt stress) (Yu et al 2023). Deionized water was set as the control (0 mg/L; mimicking no salt stress).…”

“…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).…”

“…External factors, such as salt stress, mainly mediated by soil salinization, can affect or even facilitate the process of invasion of invasive plants through competitive advantage and allelopathy (Wang et al 2019a, Bora et al 2020, Long et al 2021, Yu et al 2023). More importantly, millions of hectares of arable land worldwide are too saline to produce economic crops, and the extent of exposure to salt accumulation is increasing, with projections that ≈ 50% of arable land could be under salt stress by the mid–21 st century (Kumar et al 2020, Xu et al 2020, Kumawat et al 2022).…”