Seasonal Variation of Hordenine and Gramine Concentrations and Their Heritability in Reed Canarygrass1

Abstract

The antiquality tryptamine alkaloids and their β‐ carboline derivatives in reed canarygrass, Phalaris arundinacea L., are under relatively simple genetic control and can be eliminated by breeding. The nontryptamine alkaloids (hordenine and gramine) are more difficult remove because they can only be controlled genetically by lowering their concentrations. The objectives of this study were to determine seasonal variation of hordenine concentration, its heritability, and relationship to gramine concentration in reed canarygrass.Our studies showed high broad sense heritability estimates for hordenine and gramine of first growth and regrowth forage, a statistically significant but low positive correlation between the two alkaloids, and similar seasonal variation in their concentration. Concentration of gramine (7,000 µg/g dry wt) in regrowth forage was 10 times greater than that in first growth; concentration of hordenine (3,200 µg/g dry wt) in regrowth was twice greater than that in first growth (mean of 155 plants). Leaf blades contained higher concentrations of gramine than did leaf sheaths, whereas the converse was true for hordenine. The upper portion of the canopy contained 69% and 48% of mean herbage concentrations of gramine and hordenine, respectively. Improved techniques for extraction and colorimetric determination of the alkaloids are detailed, and the presence of nor‐gramine is reported.