QUANTITATIVE COMPARISON OF VOLATILE COMPOUNDS AMONG 7 MEDICAGO SPP ACCESSIONS

Previous research identified the presence of unique semivolatile compo unds in alfalfa weevil (Hypera postica Gyllenhal) (AW) -resistant Medi cago accessions. These compounds may impart repellency to AW in alfalf a (Medicago sativa L.). The objective of our study was to analyze with in- and between-population variation for four of these unique semivola tile compounds across eglandular and glandular-haired Medicago accessi ons. Seven Medicago accessions were evaluated under greenhouse conditi ons in an experiment arranged as randomized complete blocks with four replicates. Volatile compounds were extracted via supercritical fluid extraction and then quantitatively analyzed for levels of 2,7-dimethyl , 2,6-octadienol; cis-geraniol; 1,(E)-8,(Z)-10-tetradecatriene; and 1- hepten-3-ol. Significant difference (P < 0.05) among entries were obse rved for 2,7-dimethyl,2,6-octadienol; cis-geraniol; 1, and (E)-8,(Z)-1 0-tetradecatriene. These compounds were found only in glandular haired accessions. There were no significant differences in levels of 1-hept en-3-ol. Our findings demonstrate that the genetic incorporation of 2, 7-dimethyl, 2,6-octadienol; cis-geraniol; 1, and (E)-8,(Z)-10-tetradec atriene into cultivated alfalfa will require interspecific crossing. A lfalfa weevil behavioral tests using these compounds must be conducted prior to such crosses in order to ascertain the efficacy of repellenc y by these compounds.