Invasive Ageratina Adenophora Research Articles

Invasive Ageratina adenophora can maintain its ecological advantages over time through releasing its autotoxicity by accumulating a bacterium Bacillus cereus

Plant invasive success is attributed to invaders’ ecological advantages over their native neighbors. However, increasing evidence suggests that these advantages are expected to attenuate over time because of natural enemy accumulation, ecological evolution of native species and autotoxicity. We determined how an invasive Ageratina adenophora could remain its competitive advantages over time by avoiding its autotoxicity. Our results highlighted that the autotoxicity of A. adenophora in its invaded soil was reduced by some microbes. Moreover, an autotoxic allelochemical, 2-coumaric acid glucoside, detected in the invaded soil, demonstrated distinctly autotoxic effects on its seed germination and seedling growth. However, the autotoxic effects were greatly alleviated by a bacterium Bacillus cereus, accumulated by A. adenophora. Furthermore, the allelochemical could be almost completely degraded by B. cereus within 96 h. Accordingly, we speculate that A. adenophora could aggregate B. cereus to release its autotoxicity maintaining its competitive advantages over time.

Phytotoxic effects of invasive Ageratina adenophora on two native subtropical shrubs in Nepal

The response of native plants to allelopathic interference of invasive species may differ from species to species. In this study, the phytotoxic effects of Ageratina adenophora were tested on two native shrubs (Osbeckia stellata and Elsholtzia blanda) of Nepal. Both the shrubs were grown in pots under treatments of A. adenophora fresh leaves and root leachates, and litter. Then, the seedling length and biomass were compared among the treatments. The results show that A. adenophora litter has stimulatory effects but the leachates from fresh leaves and root are phytotoxic to the growth and development of native shrubs. Infrared Spectroscopy (IR) analysis confirmed the presence of O–H (Hydroxyl), N–H (Amines), C≡C (Alkynes), and C–H stretching (Aromatic) or C–O–C stretching (Ethers) in the leachates representing harmful allelochemicals. The invaded soil by A. adenophora had low pH and a high amount of organic matter, total nitrogen, phosphorus, and potassium than the uninvaded soil. The results indicate that the native O. stellata and E. blanda are harmed by A. adenophora in nature by leaching of allelochemicals and probably by reducing the soil pH. Overall, this study has provided valuable insights regarding the effects of A. adenophora invasion on native shrubs and revealing the potential mechanism of its invasiveness.

Germination and Early Seedling Growth of Two Rice Varieties as Affected by Invasive Ageratina adenophora

Ageratina adenophora is a perennial herb of family Asteraceae expanding as a serious threat to ecological integrity and biodiversity. This study aims to assess the allelopathic potential of fresh and dry leaf and root aqueous extracts of this invasive species on germination, early seedling growth, seedling biomass and seed vigor of two rice (Oryza sativa L.) varieties namely 6444 and 2245. The result revealed that with increasing concentration of extract, inhibition effect also increases. Leaf extract was more inhibitory than root extract and dry plant extracts had higher allelopathic impact in comparison to fresh plant extracts. Among the two investigated rice varieties 6444 was more resistant to the fresh and dry leaf extract while 2245 was more resistant to fresh and dry root extract. This study will be helpful in assessing the effect caused by A. adenophora to rice crop and could be used in devising weed control strategy.