Allelopathic suppression by Conyza canadensis depends on the interaction between latitude and the degree of the plant’s invasion

Abstract

Allelopathic suppression of the growth of co-occurring plant species in invaded ecosystems is an important factor in some plant invasions. Th is study uses leaf extracts of the invasive plant species Conyza canadensis to determine its allelopathic eff ects along a latitudinal gradient, and under diff erent cover classes and degrees of invasion, on seed germination and growth of Lactuca sativa, a sensitive bioindicator of allelochemicals. Th e allelopathic eff ects of C. canadensis on seedling height, root length, seedling biomass, germination percentage, germination potential, germination index, germination rate index, and vigor index of L. sativa increased signifi cantly with increasing latitude. A possible explanation is that the leaves of plants growing in high latitudes secrete a higher concentration of allelochemicals than do leaves of plants growing in low latitudes. Th e allelopathic eff ects of C. canadensis on seedling height, seedling biomass, germination potential, germination index, germination rate index, and vigor index of L. sativa decreased with increasing degree of invasion. Th e more intense allelopathic eff ects of C. canadensis at lower degrees of invasion may enable it to establish populations in ecosystems by inhibiting the seed germination and growth of co-occurring species.

Warming and elevated nitrogen deposition accelerate the invasion process of Solidago canadensis L.

“…Consequently, plant biomass of the invader increased significantly with the degree of its invasion, probably because of the competition pressure released from native species at later invasion stages. Furthermore, the allelopathic effects of invasive C. canadensis on the seedling height, seedling biomass, germination index and vigor index of native L. sativa weakened with a greater degree of invasion (Wang et al 2017a). As a co-invasive species, leaf extracts of S. canadensis also significantly inhibits the seed germination of native L. sativa (Wei et al 2020a), but S. canadensis has positive allelopathic effects on its own growth (Adomako et al 2019); hence, intraspecific competition in S. canadensis may be mutually beneficial.…”

“…Exotic invasive species are garnering much attention, because they can severely damage and impair the structure and functioning of native ecosystems, disrupt key ecological processes, affect agricultural production, and even cause huge economic losses worldwide (Diagne et al 2021). A species is considered invasive when it is spreading beyond its natural area of distribution (Wang et al 2017a). After successfully passing through the introduction, colonization, and establishment phases, a species finally achieves invasiveness and is often expanding its range size exponentially (invasive phase) (Dai et al 2020).…”

The latitudinal and longitudinal allelopathic patterns of an invasive alligator weed (Alternanthera philoxeroides) in China

“…The secretion of allelochemicals is influenced by both the plant itself and other biotic and environmental factors [ 14 ]. For example, a plant allelopathic intensity is increased when the plant is unfit or under stress conditions [ 15 ]. However, the process of allelochemical excretion is energy-consuming, which would affect a growth and development of the plant due to the limited resources in the plant.…”

Phytotoxic Effects of Calotrois procera (Aiton) W.T. Leaves Aqueous Extract on Seed Germination of some Cereal Crops Using Probit Analysis

“…Certain plants may have the capacity to suppress germination and development of other plants by releasing many chemical substances into the environment (Wang et al, 2017). These chemicals are known as allelochemicals (Singh and Chaudhary, 2011).…”