Effect of soil conditions on the pigment complex and stress resistance of Rhodiola rosea L. under the conditions of introduction

Abstract

The research findings on the effect of soil conditions on the pigment complex and stress resistance of Rhodiola rosea L. under introduction conditions are discussed. Rhodiola rosea is a valuable pharmacopoeial adaptogen that requires protection; its introduction is considered a strategy for ex situ conservation of the species. The research targets were agropopulations of Rhodiola rosea introduced on light gray forest podzolic soils and meadow chernozem soils in the south of the Tomsk Region. The soil indices were measured using a HydraGO probe, while the physiological state of plants was assessed with a portable Dualex Scientific+ fluorometer which allowed determining the absolute chlorophyll (Chl) and flavonol (Flav) content as well as calculating the nitrogen balance index (NBI). No statistically significant differences in soil moisture (25.1 ± 0.6% vs. 25.5 ± 1.3%) or temperature (27.3 ± 0.4°C vs. 29.3 ± 0.8°C) were found between the sites. The bulk electrical conductivity of meadow chernozem soils (0.23 ± 0.01 dS m) was significantly higher than that of light gray forest podzolic soils (0.12 ± 0.003 dS m), whereas the pore water electrical conductivity was higher in the latter soil type (0.73 ± 0.02 dS m) inducing osmotic stress. The absolute chlorophyll content in Rh. rosea leaves on meadow chernozem soils (13.67 ± 1.18) was 2.5 times higher than that in plants grown on light gray forest podzolic soils (5.40 ± 0.66); flavonol content (0.73 ± 0.05) and nitrogen balance index (18.16 ± 1.56) also increased indicating high photosynthetic activity and stress resistance. The rosavin content in underground organs reached 1.47 ± 0.06%. On nutrient-depleted light gray forest podzolic soils with low electrical conductivity (0.12 ± 0.003 dS m), suppression of physiological processes was observed (Chl 5.40 ± 0.66, Flav 0.40 ± 0.04, NBI 13.16 ± 0.42), along with accumulation of salidroside (1.94 ± 0.09%) which performed an adaptogenic function under osmotic stress. The obtained findings may be used to optimize the growing practices of Rh. rosea under plantation conditions.