Biometric and phytochemical variability of roseroot (Rhodiola rosea L.) from field cultivation

Abstract

S u m m a r y Roseroot (Rhodiola rosea L.) is an adaptogenic plant, widely used in the traditional medicine of Scandinavia, Russia, China and Mongolia. The aim of the study was to determine the biometric and phytochemical co-variability of this species under field cultivation in western Poland (Plewiska near Poznań). The plant material originated from four-year-old cultivation established twice by rhizome division in autumn 2007 and 2008. In the study, 46 individuals (23 plants in 2011 and in 2012) were used. The biometric analysis included measurements of the basic characteristics of plants related to the size (luxuriance) of clumps, shoots, leaves and rhizomes with roots (raw material). The amounts of total polyphenols (expressed as gallic acid), tannins (expressed as pyrogallol) and flavonoids (expressed as quercetin) were determined spectrophotometrically. The obtained results showed high variation of Rh . rosea, especially in the level of flavonoids (0.01-0.20% DM) and in the weight of raw material (113-1156 g FM/plant). There were observed correlations between the phytochemical (flavonoid and total phenolic content) and biometric (water content, leaf number, shoot and clump size) features.

Biometric features and content of phenolic compounds of roseroot (Rhodiola rosea L.)

“…Our previous investigations showed biometric and phytochemical co-variability of this species. We found correlations between flavonoid and total phenolic contents in the underground plant parts and biometric features, such as: water content in rhizomes with roots, leaf number per shoot as well as shoot and clump size [22]. These relationships were statistically significant, but usually not strong, and they require further, more detailed research.…”

“…According to other investigations from this region, the weight of rhizomes ranged from 50 to 840 g per plant, and the weight of aboveground parts: from 20 to 300 g plant −1 [28]. Our previous research [22] also indicated large variation of the biometric features describing the size of roseroot specimens: clumps, shoots, and leaves. For example, the height of 4-year-old plants varied from 12 to 40 cm, leaf number per shoot: 30-81, mean leaf length: 1.9-4.6 cm, and the fresh weight of raw material: from 113 to 1156 g plant −1 .…”

“…After scanning by the digiShape software [23], the roseroot leaves were used to determine leaf size and shape. In comparison with earlier research [22], leaf width in 1/4, 1/2, and 3/4 of the leaf length, leaf area, leaf skeleton length, skeleton end length, and skeleton end node number were additionally measured. Shape of leaves was described using the proportion between leaf length and width as well as the comparison of three leaf width values.…”

“…For the study, 25 morphologically diverse and well-developed plants were selected. The basic biometric measurements of plants concerning the size (luxuriance) of the clumps, shoots, leaves, and rhizomes with roots were carried out according to the methods described in the previous work [22]. From each plant, three fertile shoots of the first generation [21] were collected, and then from their upper part with the largest leaves three successive leaves were taken (nine leaves per specimen).…”

“…The obtained plant material was cut into small pieces and dried at 40°C and relative humidity of 20% in a GoBest UZ-108 heating chamber (Poznań, Poland). Water content (%) and dry weight of samples were measured after drying at 105°C in a HR73 Halogen Moisture Analyzer, Mettler Toledo (Switzerland) [22]. Airdried and powdered rhizomes with roots of Rh.…”