Submitted to: Allelopathy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/5/2001
Publication Date: 4/14/2002
Citation: Peterson, J.K., Harrison Jr, H.F., Snook, M.E. 2002. Bioassay guided isolation of seed germination inhibitors from sweetpotato [Ipomoea batatas (l.) lam. cv. Regal] cortex tissue. Allelopathy Journal, 9:177-186. Interpretive Summary: Control of weeds in vegetable crops is usually the most costly component of the production system. Traditionally suppression of weeds is achieved primarily by application of herbicides, at times including methyl bromide. For reasons of environmental protection and cost reduction integrated pest management has been advocated. In these systems breeding for host plant resistance is considered the preferred and most economical way. In this paper the isolation and efficacy of natural weed suppressing chemicals occurring in sweetpotato are described. It was shown that at very low concentrations, around 70 parts per million, the germination of weed seeds was severely suppressed. The investigation of breeding potential to increase the levels of these compounds is the logical extension of research reported here.
Technical Abstract: Methanolic extracts from cortex tissue of the sweetpotato cultivar 'Regal' inhibited germination of proso-millet seed. Bioassays of fractions obtained by low pressure preparative column chromatography revealed three major regions in the elution profile, that had inhibitory activity. The most active fraction was further separated by semi-preparative HPLC. Eight tmajor peaks that suppressed seed germination were obtained. Except for on peak, the compounds represented by the other peaks displayed activities not statistically different from each other. Fifty percent inhibition, relative to the control was obtained with an average of 73micrograms per ml germination water. Gas chromatography - mass spectrometry data obtained from hydrolysis products allowed identification of a few components of these molecules i.e., the fatty acids, palmitic, linoleic, linolenic and a saturated, as well as a mono-unsaturated C 22 acid.