A methodology for extraction of 2-tridecanone (2-T) and 2-undecanone (2-U) from tomato plants {Lycopersicon spp.) was developed using leaves of a commercial cultivar previously fortified with these allelochemicals. Extracts were analyzed in a gas chromatograph, using the following methods: chloroform; chloroform plus Butt extractor; and Butt extractor. The three methods recovered more than 80% of the allelochemicals. However, the first method was more pratical, using less volume of solvent. The genotypes Lycopersicon hirsutum f. glabratum (PI 134417), L. esculentum ('Santa Cruz Kada AG-373'), and 22 hybrids F1 (RC1) [(PI 134417 x L. esculentum} x PI 134417) were analyzed for the amounts of these allelochemicals. Among the hybrids, six presented both 2-T and 2-U, and four presented only 2-T. The highest concentration of allelochemicals was 351 ppm of 2-T, and 62 ppm of 2-U. The allelochemicals were not detected in L. esculentum. The concentrations of 2-T and 2-U in PI 134417 were 1902 and 473 ppm, respectively.
Insecta; Lycopersicon hirsutum f. glabratum; allelochemicals; plant resistance
