Alejandra Gil

Essential oil yield and composition of Tagetes minuta accessions from Argentina

Abstract Six wild Tagetes minuta accessions were collected from different locations in Argentina and were grown in the same environment to investigate their essential oil yield and composition. Essential oil yield differed among accessions. Essential oil production of Buenos Aires and Mendoza accessions did not change between years, and Mendoza always yielded more than Buenos Aires. There was no correlation between the yield of essential oil and the total aerial biomass. Regardless of the accessions origin, dihydrotagetone, α -phellandrene, limonene, o -cymene, as well as the isomers of β -ocimene, tagetone and tagetenone were the major constituents of the essential oil. Three chemotypes were identified. Chemotypes differed in biomass production and essential oil yield of inflorescences and leaves. Leaves of the Mendoza accession were rich in dihydrotagetone as opposed to those of Buenos Aires, while the inflorescences of Mendoza accession, as well as the inflorescences and leaves of Buenos Aires have similar dihydrotagetone contents.

Response of winter crops differing in grain yield and essential oil production to some agronomic practices and environmental gradient in the Rolling Pampa, Argentina

Abstract Intensive land use in the Rolling Pampa of Argentina generates heterogeneous environmental and ecological conditions associated with agronomic practices. The yields of crops with different resource allocation to the production of primary or secondary metabolites could vary with the environment. Crops that mainly produce primary metabolites would have high yields under favorable environments, and crops that produce high quantities of secondary metabolites would have high essential oil yield under unfavorable environments. To test whether this hypothesis is applicable under the Rolling Pampa conditions, field experiments were conducted with the following objectives: (1) to compare biomass and grain yield in three winter crops: wheat (Triticum aestivum L.), coriander (Coriandrum sativum L.) landrace with high essential oil content (HEO) and coriander landrace with low essential oil content (LEO), grown at different levels of N fertilization and weed control; and (2) to determine relative changes in grain yield, essential oil production and harvest index with environment in the coriander landraces. The crops were grown at two locations differing in physical and chemical soil degradation due to the intensity of land use. Wheat allocated resources mainly to the production of primary metabolites, producing higher biomass and grain yield in the favorable environments. The HEO coriander landrace, which allocates resources to the production of both primary and secondary metabolites, produced similar biomass and grain yield in both locations, but resource partitioning to the production of essential oils was high under unfavorable environmental conditions. The LEO coriander landrace which allocates resources mainly to the production of primary metabolites and, in a minor proportion, to secondary metabolites, produced high biomass and grain yield in intermediate environments and high essential oil yield under unfavorable environments. The environmental conditions of the Rolling Pampa that curtailed the allocation of resources to the production of grain yield promoted the production of essential oils. Based on these results, under poor soil environments, one option is to produce crops with essential oils as marketable yields, instead of adding inputs to improve soil condition and produce traditional crops, where yield is very sensitive to environmental variations.

Characterization of Lemon Verbena (Aloysia citriodora Palau) from Argentina by the Essential Oil

Abstract The oils of twenty-three samples of Aloysia citriodora from the most important growing areas in our country have been analyzed using GC/FID/MS. Characterization of the oil compositions revealed chemical markers which can be used to define the quality of a typical Argentine lemon verbena. In addition to the normal neral (20.0%) and geranial (29.0%) rich oils, two unusual oil compositions were detected: one with high contents of limonene (40.3%) and citronellal (21.6%), the other rich in β-thujone (73.4%). These specifications can be used for the standardization of this plant, defining the best available quality of leaves and volatile fractions of argentine lemon verbena, and discriminating from potentially toxic materials and adulterants.

Response of Coriander (Coriandrum sativum L.) to Nitrogen Availability

ABSTRACT A greenhouse hydroponics system was used to analyze biomass partitioning between primary and secondary metabolites in coriander at different levels of nitrogen availability and a field fertilization experiment was used to evaluate the response of coriander to supplemental nitrogen. Resource partitioning in an Argentinian land-race between primary and secondary metabolites at different levels of nitrogen treatment was asymptotic for biomass, fruit yield, and essential oil production. In a European land-race, resource partitioning was asymptotic to nitrogen treatment for biomass and fruit yield, but parabolic for essential oil production. The response to nitrogen was related to genotypic characteristics of the two land-races and suggest that relatively high levels of nitrogen fertilizer should be used in production of Argentinian land-race coriander and relatively moderate levels of nitrogen fertilizer should be used in production of European land-race coriander.

Root thiophenes in Tagetes minuta L. accessions from Argentina: genetic and environmental contribution to changes in concentration and composition

Three wild Tagetes minuta accessions were collected from Buenos Aires, Mendoza, and Salta provinces in Argentina and were grown in the same environment to study the concentration and composition of root thiophenes, and the production of aerial biomass. The accessions showed quantitative, but not qualitative differences in thiophenes. Five thiophenes were identified. In the Buenos Aires and Salta accessions, concentrations of total thiophenes were independent of changes in aerial biomass production, but in the Mendoza accession we found a positive correlation between total thiophenes and aerial biomass. In the Mendoza accession we observed dramatic changes in the concentration of thiophenes between years. The composition of thiophenes in the Salta and Mendoza accessions was characterized by low concentrations of BBT and α-T and high concentrations of BBTOH, whereas thiophenes in the Mendoza accession had a higher concentration of BBTOH than did the Buenos Aires accession.