Adaptability of two accessions of Geranium macrorrhizum L. to drought stress conditions

Abstract

Geranium macrorrhizum L. is a herbaceous perennial with underground stems (rhizomes) naturally found in the Balkan countries where it is known for its phytochemical properties. Despite its potential, there are no references to cultivation of this species to produce essential oil; to date only wild plants have been harvested. The purpose of this study is to compare cuttings of G. macrorrhizum taken from different starting material in terms of resistance drought stress and their morphological and physiological growth responses. Cuttings from two different origins (n=5), the English variety called ‘Bevans’ (BV), and a wild geranium population from Hungary (GH) were studied. Water potential (ψ) was measured with a Scholander chamber for one month (August) during which time the plants did not receive any water. Once the water potential curve was obtained, the morphological and functional components of the growing process were measured in 5 plants from each accession: leaf area ratio (LAR), leaf mass fraction (LMF), root mass fraction (RMF), water stored in the aerial part (WSL) and water stored in the roots (WSR). Both accessions maintained water potential unaltered for 20days, GH losing more water during the experiment. Results show that the LAR for GH plants was 3 times higher than for BV plants (631.7 and 247.3 respectively). Regarding biomass distribution, GH plants had a greater LMF (0.41) and consequently a higher WSL in leaves (37.96). BV plants exhibited a higher RMF (0.87). Despite being the same species, the two accessions show important morphological and physiological differences which are most likely the result of the selection process to achieve the ‘Bevan’ variety used for ornamental purposes.