Morphological characteristics of Impatiens flanaganiae Hemsl. grown under different light conditions

Abstract

Impatiens flanaganiae Hemsl. is a rare plant which preferentially grows in shady conditions and exhibits strong apical dominance. The morphological plasticity of I. flanaganiae in response to light intensity in laboratory conditions was investigated. Unbranched plantlets of I. flanaganiae propagated from tubers were exposed to three light regimes: 30, 55 and 280 microeinsteins m− 2 sec− 1 for a period of seven weeks. Plants grown under lower light intensity (30–55 microeinsteins m− 2 sec− 1) developed long unbranched stems about 65 cm in length and fewer leaves with a large leaf area. In contrast, reduced stem extension (up to 35 cm) and multiple lateral branches were observed in plants exposed to higher light intensity (280 microeinsteins m− 2 sec− 1). A significant increase (at 5% level) in the number of leaves in plants from this variant was found to be inversely proportional to the leaf area. Extended exposure of the plants to higher light intensities seems to be stressful and resulted in abnormal biochemical and morphological changes such as chlorosis, necrosis and curling of the leaves. The strong increased premium on lateral growth of I. flanaganiae, induced by light intensity of 280 microeinsteins m− 2sec− 1 resulted in a greater number of lateral branches which were found to be suitable for its rapid and more efficient propagation in vivo by cuttings or in vitro by shoot tip culture.