Impact of nitrogen nutrition on growth and plant quality of Centella asiatica

Due to its bioactive triterpene saponins, Centella asiatica (L.) Urb. has been used as a medicinal herb since ancient times and its economical importance is still rising [1,2,3]. Up to now plants are collected spontaneously which implicates a large variation in plant and product quality depending on the origin, genotype and time of harvest of the plants [1–4]. To assure high plant quality, it will be necessary to encourage cultivation of Centella. To our knowledge there is scarce information on cultivation techniques, especially on mineral nutrition of Centella plants. The aim of this study was to investigate the effects of nitrogen on growth and saponin biosynthesis of Centella asiatica and to find appropriate parameters to evaluate quality of plant material by non-destructive measurements in situ. Plants were grown for eight weeks in rock wool cubes in a greenhouse and fed with five nutrient solutions differing in their nitrogen concentrations. Number of leaves and stolons, length of stolons, assimilation rate and leaf green intensity were monitored weekly. Non-destructive measurements were conducted with a portable optical sensor (Multiplex® Research, Force-A, France) recording the fluorescence signature which is associated with plant constituents. Fresh and dry weight of leaves and stalks, leaf area and specific leaf weight were ascertained biweekly, while examination of leaf chlorophyll and leaf nutrient content was carried out once at the end of the study. Leaf samples for determination of triterpenoid content were harvested four times. Analyses of asiaticoside and asiatic acid by HPLC are in progress and will be discussed.

Acknowledgement: Regionale 2010, State of North Rhine-Westphalia (Germany); Institute of Systematic Botany, The New York Botanical Garden (USA), A.N. Nicolas; Institut Malgache de Recherches Appliquées (Madagascar), D. Randriamampionona; National Center for Natural Products Research, University of Mississippi (USA), B. Avula; Unité d'Analyse Chimique et Physico-Chimique des Médicaments et Pharmacognosie, Université Catholique de Louvain (Belgium), M.H. Rafamantanana; Institute of Nutrition and Food Sciences, University of Bonn (Germany), B.F. Zimmermann.

References: 1. Thomas MT et al. (2010) Ind Crop Prod 32: 545–550.

2. Devkota A et al. (2010) Biochem Syst Ecol 38: 12–22.

3. Randriamampionona D et al. (2007) Fitoterapia 78: 482–489.

4. Sritongkul J et al. (2008) Acta Hort 804: 367–372.