Growth responses of Lantana (Lantana camara L.) varieties to varying water availability and light conditions

Lantana camara L. (Verbenaceae) is an invasive alien species in many countries that causes economic losses and harmful ecological impacts on biodiversity. Its varieties with colourful flowers are being introduced to the horticulture trade in Sri Lanka despite that the orange-red flowered L. camara var. splendens and yellow-pink flowered L. camara var. camara introduced to the country in the nineteenth century have been naturalised and considered as invasive alien species of national significance. This study compared drought and shade tolerance abilities of white and purple flowered ornamental L. camara varieties with the above two naturalised varieties using statistical analysis. The results provided evidences for significant differences in drought and shade tolerance abilities between naturalised and ornamental L. camara varieties in Sri Lanka with regard to growth of the main stem, flowering, fruiting, defoliation, leaf water content and leaf growth rate, leaf area, photosynthetic tissue mass and pigment content, stomatal density, root volume and biomass partition between above and below ground parts. While contributing to fill in the knowledge gap in the biology of 'Lantana group', we report that ornamental L. camara varieties are not drought and shade tolerant as the naturalised varieties, and therefore their potential invasiveness may not be as high as the wild varieties that pose a great threat to the biodiversity of Sri Lanka.