Recruitment and competitive interaction between ramets and seedlings in a perennial medicinal herb, Centella asiatica

Abstract

Centella asiatica (L.) Urban, a clonal perennial and medicinally important herb, is found throughout India in moist places up to an altitude of 1800 m. Plant reproduces both through vegetative (ramets) and sexual (seedling) means. The present study was undertaken to investigate (1) the recruitment pattern of ramets (R) and seedlings (S) in natural populations, and (2) the relative competitive ability and the pattern of allocation of resources in S and R plants grown in mixed culture. Individuals of similar size from the two populations raised through nodes and seeds were grown in pure and mixed stands at the same overall density but with different proportions by using de Wit's "replacement series". There were significant differences in growth parameters, viz. leaf number, leaf area, number of stolons, number of daughter ramets, total biomass, relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR) and crude reproductive effort (CRE) due to proportions and population types. Total biomass, leaf area, and numbers of leaves, stolons, daughter ramets, and seeds were higher for ramets at all proportions. RGR and LAR were also higher for ramets, while NAR was higher for seedlings. NAR and CRE were enhanced due to competition in both the ramets and seedlings. Growth performance per pot was higher in monoculture than in mixed culture. Higher relative yield and competitive ability of ramets as compared to seedlings were not due to initial advantage of higher biomass. Relative yield total showed that both types of populations competed for the same resources. In nature, the ramets play a greater role in population maintenance of C. asiatica.