Barnyardgrass growth inhibition with rice using high-performance liquid chromatography to identify rice accession activity

Some accessions of rice (Oryza sativa L.) have been shown to inhibit the growth of barnyardgrass (Echinochloa crus-galli (L,) Beauv,), Our objective was to determine if high-performance liquid chromatography (HPLC) chromatograms from leaf extracts of different accessions of rice correlated with weed control activity. Chromatograms of extracts consisting of 10 mg of fresh leaf tissue per milliliter of methanol (CH,OH) were obtained from 40 accessions of rice. Cluster analysis was performed using 20 peaks from the chromatograms, Three clusters were found, with one cluster being distinctly separated from the other two, Although weed control data are not available for all the accessions, the isolated cluster contains all of the accessions that have been shown to inhibit growth of barnyardgrass and none that do not. This indicates that the assay could be used gear-round to screen accessions of rife for weed control potential to determine which accessions should be further tested in the field, This could be done in a relatively short time using a small amount of space in the greenhouse, Because the assay requires only 10 mg of tissue per milliliter of methanol, it may potentially be used to test individual plants within an accession for weed control potential in a nondestructive manner.