The chemical analysis of liquid and vapor phase of essential oils (EOs) obtained from the leaves of Juniperus communis var. saxatilis (Cupressaceae) and Larix decidua Mill. (Pinaceae) was performed by solid-phase micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) techniques. The results highlighted a rich composition characterized by 51 identified volatile compounds (33 in J. communis and 38 in L. decidua). In both oils, monoterpenes prevailed over the sesquiterpenes, albeit with qualitative and quantitative differences. Sabinene (37.5% and 34.5%, respectively) was the two most abundant component in the liquid and vapor phase of J. communis while α-pinene (51.0% and 63.3%) was the main constituent in L. decidua. Among others, α-terpinene (2.4% and 5.8%), cis-thujopsene (2.1%) and d-cadinene (2.4%) were detected only in J. communis as well as b-ocimene (10.2%), 1,8 cineole (3.2% and 1.9%) and L-pinocarveol (1.1% and 0.3%) were characteristics of L. decidua. The phytotoxic activity of the two EOs was assessed in pre-emergence conditions using three concentrations in contact (2, 5, 10 μL/mL) and non-contact (2, 20, 50 μL) tests against Lolium multiflorum Lam. (Poaceae) and Sinapis alba L. (Brassicaceae). When the filter paper was used as a substrate, the treatments were very effective in dose-dependent inhibition of germination (up to 100%).Their effectiveness was reduced by the interaction with soil. Despite this, significant data were obtained (p-values < 0.05). In this regard, the direct contact of the seeds with J. communis EO decreased the L. multiflorum and S. alba germination from 1.5 to 3.5 times compared to the non-contact test and had a greater impact on the shoot growth (up to + 7% and +10%). Otherwise, L. decidua EO achieved similar results in terms of germination (-45% to -50% for L. multiflorum and -39% to -43% for S. alba) and seedling development (from - 59% to -60% for L. multiflorum and -40% to -43% for S. alba) in both tests at the maximum used concentration/dose. An exploratory investigation is currently underway to detect the residual presence of volatile compounds in the soil at the end of the tests.

CHEMICAL PROFILE OF ESSENTIAL OILS FROM JUNIPERUS COMMUNIS VAR. SAXATILIS PALL. (CUPRESSACEAE) AND LARIX DECIDUA MILL. (PINACEAE) AND THEIR PHYTOTOXIC EFFECTS ON DICOT AND MONOCOT SPECIES

Stefania Garzoli
2022

Abstract

The chemical analysis of liquid and vapor phase of essential oils (EOs) obtained from the leaves of Juniperus communis var. saxatilis (Cupressaceae) and Larix decidua Mill. (Pinaceae) was performed by solid-phase micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) techniques. The results highlighted a rich composition characterized by 51 identified volatile compounds (33 in J. communis and 38 in L. decidua). In both oils, monoterpenes prevailed over the sesquiterpenes, albeit with qualitative and quantitative differences. Sabinene (37.5% and 34.5%, respectively) was the two most abundant component in the liquid and vapor phase of J. communis while α-pinene (51.0% and 63.3%) was the main constituent in L. decidua. Among others, α-terpinene (2.4% and 5.8%), cis-thujopsene (2.1%) and d-cadinene (2.4%) were detected only in J. communis as well as b-ocimene (10.2%), 1,8 cineole (3.2% and 1.9%) and L-pinocarveol (1.1% and 0.3%) were characteristics of L. decidua. The phytotoxic activity of the two EOs was assessed in pre-emergence conditions using three concentrations in contact (2, 5, 10 μL/mL) and non-contact (2, 20, 50 μL) tests against Lolium multiflorum Lam. (Poaceae) and Sinapis alba L. (Brassicaceae). When the filter paper was used as a substrate, the treatments were very effective in dose-dependent inhibition of germination (up to 100%).Their effectiveness was reduced by the interaction with soil. Despite this, significant data were obtained (p-values < 0.05). In this regard, the direct contact of the seeds with J. communis EO decreased the L. multiflorum and S. alba germination from 1.5 to 3.5 times compared to the non-contact test and had a greater impact on the shoot growth (up to + 7% and +10%). Otherwise, L. decidua EO achieved similar results in terms of germination (-45% to -50% for L. multiflorum and -39% to -43% for S. alba) and seedling development (from - 59% to -60% for L. multiflorum and -40% to -43% for S. alba) in both tests at the maximum used concentration/dose. An exploratory investigation is currently underway to detect the residual presence of volatile compounds in the soil at the end of the tests.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11573/1652457
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