A rapid semi-quantitative procedure for screening hydrocyanic acid in white clover (Trifolium repens L.)

Abstract

The presence of cyanogenic glucosides in white clover (Trifolium repens L.) is an anti-nutritional factor due to the potential for cyanide to pre-dispose selenium deficiency in grazing animals. Considerable genotypic variation in cyanogenesis occurs in white clover and it is important that highly cyanogenic white clover lines are identified to ensure that germpasm used in breeding programs does not lead to the release of cultivars that exceed safe levels. A procedure for rapid semi-quantitative screening of large white clover germplasm collections is described. This procedure is based on the picrate assay and utilises computer imagery and calibration relationships between spectral intensity (red, green, blue bands) of the colour reaction on picrate paper with cyanide in standard solutions to predict hydrocyanic acid concentration in white clover leaf.