Relation of Hydrocyanic Acid Potential of Leaf Samples to That of Whole Plants of Sorghum1

Abstract

AbstractThe relationships between the hydrocyanic acid potential (HCN‐p) of leaves and whole plants were studied in ‘Piper’ sudangrass, Sorghum bicolor var. sudanense (L.) Moench, and ‘Suhi‐l’, sorghum‐sudangrass hybrid, S. bicolor ✕ S. bicolor var. sudanense, subjected to three cutting managements. The results were: Leaf and whole plant samples from Suhi‐1 were usually higher in HCN‐p than samples from Piper at all harvest dates for the three cutting managements. Plants cut at 10 cm when they reached the early bloom stage had significantly lower average HCN‐p than plants cut at 8 and 20 cm when they reached a height of 50 and 75 cm, respectively. Differences in average HCN‐p for the two latter cutting management were not signifant. There were no significant differences among average HCN‐p of the whorl and the first and third leaves of Piper. For Suhi‐1, no significant difference was found between the average HCN‐p of the whorl and the first leaf. Both the whorl and the first leaf were significantly higher in HCN‐p than the third leaf. There were no consistent trends in HCN‐p associated with successive harvest dates during the season. Most of the simple correlation coefficients between HCN‐p of leaf samples and of whole plants were highly significant, indicating that leaf samples could be used to rank varieties for HCN‐p. Ratios of leaf to whole plant HCN‐p were inconsistent; therefore, such samples are not suitable for estimating the total amount of HCN‐p of whole plants.