Siam weed (Chromolaena odorata) and Crofton weed (Ageratina adenophora), are two of the most problematic invasive species in South Yunnan, China, where they show mosaic distribution patterns.The two species co-occur in transition zones, including regions with middle latitudes, such as Pu'er, and areas at low latitudes but with high altitudes, such as Kongmingshan in Xishuangbanna. These distribution patterns make them ideal candidates for comparative studies on plant invasion.
In a study published in Integrative Conservation, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) investigated how temperature, water stress, and salt (NaCl) affect seed viability and germination of the two invasive species.
The researchers collected seeds of these two species, each from three of four provenances, and carried out laboratory experiment. They heated seeds at 40°C for 1 to 10 days and at temperatures between 30°C and 95°C to test their tolerance to high heat. They examined the high-temperature tolerance and germination responses under high temperature and water stress of seeds from three of four invaded provenances to better understand how seed trait–habitat interactions influence the distribution of these two invasive species.
The results revealed that both species vary in their ability to tolerate high temperatures. Chromolaena odorata seeds were generally more tolerant to high temperature, water, and NaCl stress than Ageratina adenophora seeds. Chromolaena odorata seeds from lower latitudes and/or lower altitudes performed better than those from higher latitudes and/or higher altitudes. Conversely, Ageratina adenophora seeds from higher latitudes and/or higher altitudes were more resilient than those from lower latitudes and/or lower altitudes.
The findings suggest that high temperatures could influence the distribution of these species by affecting seed development, seed ageing, and seed germination, highlighting the role of thermal adaption in the spread of invasive plants.
Contact
WEN Bin Ph.D
CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China
E-mail: wenb@xtbg.org.cn
First published: 10 March 2025
