Updates Made on the Responses of Invasive Mikania Micrantha and Chromolaena Odorata to Contrasting Growth Irradiance and Soil Moisture

Mikania. micrantha (Kunth), a perennial herbaceous weed vine, and Chromolaena. odorata (L.), a perennial herbaceous shrub, are two most notorious invasive weeds in southern China. Due to their high competitiveness, with ability to spread and establish rapidly, both species have invaded a wide range of areas in southern China since the late 1980s and caused serious damage to seminatural forests, pastures, crops and plantations.

In this context, Dr. Lingling Zhang and Prof. Dazhi Wen investigated the structural traits and photosynthetic physiological responses of the two weeds to three levels of growth irradiance (full, medium and low irradiance) and soil moisture (full, medium and low field water content) in field glasshouses. They demonstrated that both weeds favored high light conditions, while differing in their soil water preferences: M. micrantha was particularly efficient at full soil water and C. odorata at moderate soil water conditions; limited light availability under extreme shade particularly restricted the growth of M. micrantha. Their research revealed that both weeds had developed effective mechanisms for their acclimations to high irradiance: except high light energy use efficiency in both species, M. micrantha had higher Chl a/b ratio and mainly achieved photoprotection by a non-photochemical mechanism, while C. odorata was less sensitive to changing irradiance and soil moisture.

Besides, they also determined the impacts of Bemisia tabaci infestation on the damage of M. micrantha, and found that alterations in photosynthetic apparatus and disruption of antioxidant enzymes induced by Bemisia tabaci infestation might as consequences to accelerate the senescence of M. micrantha.

Papers have been published in Journal of Plant Research (2009), Biologia Plantarum (2009), and Photosynthetica (2008).