An appraisal of the phonological ecological and biochemical aspects imparting invasive character to the alien weed Parthenium hysterophorus L

Abstract

Parthenium hysterophorus L., a member of family Asteraceae and a native of the American continent, is an invasive plant species of India. The present study evaluates certain invasive attributes in P. hysterophorus that play a major role in its spread but were not given due attention by the researchers. Phenological adaptations of P. hysterophorus in response to climatic variations were studied as per a standardized phenological scale. The study implicates that the plant is extremely adaptable towards seasonal shifts, except the initiation of reproductive phase, which was hindered under low temperature conditions. Thereafter, intraspecific variations present in the population of P. hysterophorus were evaluated through field surveys and experimental dome studies. The study indicated the presence of two morphotypes, PA and PB in the population of P. hysterophorus which differed in biomass allocation patterns, vegetative traits, and reproductive output. Further, these morphotypes had a variable phytotoxic and ecological impact on the associated plant species with PB exhibiting a higher impact. It was also interpreted that a combination of inherent and ecological factors might be responsible for inducing this phenotypic variability in P. hysterophorus. Further, P. hysterophorus was compared with other invasive/ non-invasive members of family Asteraceae to find out the invasive traits of this family. It was inferred that specific leaf area, leaf dry matter content, maximum quantum efficiency of photosystem II, leaf elemental nitrogen, carbon nitrogen ratio, leaf construction costs, flowering period, and seed germination were found to be strongly associated with the invasiveness of members of family Asteraceae. newline