Estimating hydrocyanic acid potential sorghum plants from leaf samples

All of the species and varieties of the genus Sorghum contain dhurrin, the precursor of hydrocyanic acid (HCN). Hydrocyanic acid is one of the most powerful poisons found in nature (9). Sorghums have become an important summer crop in the United States. In 1954 there were 20,148,000 acres grown with the largest amount being grown in the dryer areas of Texas, Oklahoma, and Kansas (35), An estimated 30,000 acres were grown in Tennessee in 1961; with the advent of more productive hybrids between sorghum and Sudangrass the acreage probably will increase (18), Sudangrass (Sorghum vulgare var. sudanense Hitchc.) is the most widely used summer annual pasture crop now grown in the United States (34). In comparison with sorghum (Sorghum vulgare Pers.) Sudangrass is relatively low in HCN content. However, under certain conditions, the HCN content of Sudangrass may be high enough to be fatal to cattle. Hybrids between sorghums and Sudangrass are likely to be higher in HCN than the Sudangrass parent (28). The objectives of this study were; (1) to determine if a small portion of various leaves will give a representative sample of the hydrocyanic acid potential of the whole plant; (2) to determine the effect of three different cutting managements on hydrocyanic acid potential; and (3) to determine the extent of variation in hydrocyanic acid potential among varieties.