Occurrence and distribution of Alternanthera bettzickiana (Regel) Voss., an invasive weed in the uplands of Kerala

Abstract

A survey was conducted in the uplands (or garden lands) along roadsides, uncultivated areas and in wastelands in seven agro-ecological units (AEUs) representing the central zone of Kerala during 2020 and 2021 to assess the occurrence and invasiveness of Alternanthera bettzickiana (Regel) Voss. The weed exhibited highest summed dominance ratio and importance value index in all but one of the AEUs. Diversity indices like Shannon-Wiener index, Simpson’s diversity index and Evenness index were lower for a particular region (AEU 9), showing the dominance of this weed species there. The density of A. bettzickiana was positively correlated with nitrogen content, and dry matter production was influenced by both organic carbon and nitrogen content of the soil. The study concluded that A. bettzickiana is gaining the status of problematic weed in the central parts of Kerala, dominating mostly in uncultivated areas with occational occurrence observed in cropped lands also. Hence, efforts to prevent its spread need to be taken up by concerned authorities.