Essential oils obtained by hydrodistillation from leaves of Mentha pulegium L. and Mentha rotundifolia (L.) Huds. from Uruguay were analysed by GC-FID and GC-MS. Oxygen-containing monoterpenes were the main group of constituents in both oils. Pulegone, isomenthone and menthone were the major components in the oil of M. pulegium, whereas piperitenone oxide and (Z)-sabinene hydrate were the major ones in M. rotundifolia. Enantiomerically pure (-)-menthone, (+)-isomenthone, (+)-isomenthol, (-)-menthol and (+)-pulegone were detected by multidimensional gas chromatography in the case of M. pulegium oil.
Óleos essenciais obtidos por hidrodestilação das folhas de Mentha pulegium L. e Mentha rotundifolia (L.) Huds. do Uruguay foram analisados por GC-FID e GC-MS. O grupo de monoterpenes oxigenados foi o mais importante em ambos os óleos, sendo que a pulegona, isomenthona e menthona foram os constituintes maioritarios no óleo de Mentha pulegium, no entanto, o ôxido de piperitenona e (Z)-hidrato de sabineno foram os maioritarios na Mentha rotundifolia. (-)-mentone, (+)-isomentone, (+)-isomenthol, (-)-menthol e (+)-pulegone enantioméricamente puras foram detectadas por cromatografía gasosa multidimensional no caso do óleo de Mentha pulegium

Doubled haploids (DHs) are becoming increasingly important in crop breeding programmes but methods for producing oat DHs remain inefficient. In this study haploid and DH oat plants were produced using the oat · maize hybridization method. Factors influencing the rate of caryopsis and haploid embryo production including genotype, post-pollination plant growth regulator application and temperature were investigated. The four growth regulators tested showed significant differences in their capacity to induce caryopsis formation with dicamba producing the highest numbers of caryopses, followed by picloram, 2,4-dichlorophenoxyacetic acid (2,4-D) and gibberellic acid (GA 3 ). No significant differences were observed between these growth regulators for their effect on embryo production. The concentration of dicamba was also important and was found to influence caryopsis but not embryo production, with 50 and 100 mg/l dicamba producing significantly more caryopses than 25 or 5 mg/l. Temperature had a significant impact on both caryopsis and embryo production with the magnitude and direction of response depending on genotype. Rates of haploid embryo production observed were between 0.8% and 6.7% of the pollinated florets. The proportion of haploids, which survived and were successfully doubled with colchicine following transfer to soil was between 72% and 81%.

No abstract

No abstract

The essential oil of aerial parts of Lippia alba (Mill.) N. E. Brown cultivated in a small-scale experimental area was analysed by GC and GC-MS (quadrupole). Twenty-seven components were identified, corresponding to 93% of the total oil. The enantiomeric distribution of˛-pinene, sabinene, limonene and linalool was studied by multidimensional GC-GC. The major component was linalool (55%) with an enantiomeric purity of 99% for (C)-linalool. Comparison with previous results suggested the presence of a new linalool-rich chemotype for L. alba.