The influence of NaCl salt stress on the yield and quality of the essential oil from two varieties of rose-scented geranium (Pelargonium graveleons L’Hér.)

Abstract

The pot experiment was carried out in greenhouse conditions by using two popular varieties viz., CIM-Pawan and CIM-Bio-G-171 of rose-scented geranium to know the effect of NaCl solution on the morphological traits, essential oil content, chemical composition, and yield. The plants were exposed to varying levels of NaCl solutions viz., 0, 50, 100, 150, and 200 mM. Normally, the geranium essential oil is rich in isomenthone, geraniol, citronellol, linalool, geranyl formate, citronellyl formate, and 10-epi-γ-Eudesmol. However, the quality of geranium oil is determined by the ratio of geraniol and citronellol (approximately 1:1). The plants were treated with different concentrations of NaCl viz., 100, 150, and 200 mM, and different morphological, oil content, and oil quality parameters were measured. The analysis of variance of morphological, as well as oil content and constituents showed significant variations in both varieties. As results indicated that some components trend in the positive direction and some in the negative direction. Isomenthone and citronellyl formate contents were increased, whereas, geraniol and linalool contents were reduced significantly as the concentration of salt increased in both the varieties. Citronellol and geranyl formate contents were not affected by different salt concentrations. All the Morphological traits were affected and decreased at the varied level of salt concentrations. A higher concentration of NaCl reduced the leaf length, leaf width, and herb yield in both varieties. However, the oil content reduction started even at 50 mM salt concertation, however, the reduction was more in 100, 150, and 200 mM NaCl concentrations. In general, based on the present experimental results, the morphological, quality parameters of the geranium crop were affected even with the NaCl concentration of more than 50 mM. Irrigation of NaCl-containing water (soil salinity or water salinity) may provide ways to alter the concentration of essential oil, compositions and yield, and yield-related characters in rose-scented geranium. This study showed that soil salinity might modulate the biosynthesis of essential oil constituents in rose-scented geranium.