Seasonal variations in hydrogen cyanide concentration of three Lotus species

Cyanogenic glucosides, generally considered antinutritional factors, are im portant defense molecules against predators and, in some cases, diseases. T he objectives of this study were: (i) to determine the seasonal variations in hydrogen cyanide (HCN) concentration of three widely grown Lotus spp. an d (ii) to assess the overall cyanogenic potential of the different plant co mponents of a rhizomatous cultivar of broadleaf birdsfoot trefoil [Lotus co rniculatus L.] (BFT). In this study, we used BFT cultivars Norcen and ARS-2 620, narrowleaf trefoil (L. glaber Mill.) germplasm ARS-1207, and big trefo il (L. uliginosus Schkur.) germplasm ARS-1221. The experiments were conduct ed in the field and greenhouse using a randomized complete block design. Si gnificant seasonal variations in HCN concentrations in Norcen, ARS 2620, an d ARS-1207 were observed. Hydrogen cyanide concentrations were greatest in spring and summer and least in winter. ARS-1221 was acyanogenic, Of tire th ree cyanogenic entries grown in the field study, ARS-1207 had the greatest concentration of HCN, averaging 900 mug g(-1) dry matter while Norcen and A RS-2620 had similar levels of HCN. In the greenhouse, Norcen and ARS-1207 h ad greater HCN concentrations than ARS-2620. partitioning of the rhizomatou s BFT cultivar ARS-2620 demonstrated that leaves and powers produced the gr eatest concentration of HCN, five times as much as stems and ripe-seed pods . Rhizomes, which are typically produced in winter and fall, did not exhibi t HCN production. Seeds of Norcen and ARS-2620 were acyanogenic, but ARS-12 07 seeds were weakly cyanogenic. However, as seeds germinated and seedlings formed cotyledons, Norcen, ARS-2620, and ARS-1207 exhibited HCN. Roots of all species were acyanogenic.