Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/11/2005
Publication Date: 6/12/2005
Citation: Foster, J.G., Cassida, K.A., Gonzalez, J.M., Ritchey, K.D., Sanderson, M.A. 2005. Impact of phosphorus fertility on sesquiterpene lactone concentrations in forage chicory cultivars. p. 36, 237-241. In K. Cassida (ed.) Proc. Amer. Forage Grassl. Counc., Vol. 14, Bloomington, IL. 11-15 June 2005. AFGC, Georgetown, TX.
Interpretive Summary: Chicory (Cichorium intybus L.) possesses numerous traits that make it a potentially valuable pasture species for the Appalachian hill lands, but high concentrations of bitter sesquiterpene lactones (SLs) in plants grown on phosphorus-deficient soils may adversely impact palatability of the herbage. Therefore, we investigated whether SL concentrations in chicory herbage can be manipulated with P fertilization. The effect of P fertilization on SL concentration differed among the cultivars Forage Feast, Grasslands Puna (Puna), Six Point, INIA le Lacerta (Lacerta), and La Niña. In initial growth, SL concentrations decreased as P fertility increased. Concentrations of SLs were higher in regrowth than in initial growth, and the relationship between SL concentration and P fertility in regrowth was not consistent among cultivars. Fixation of P by the soil may have been responsible for fertility response differences for SL concentration in initial and regrowth herbage. Sesquiterpene lactone concentrations were highest in Forage Feast, intermediate in Six Point and Puna, and lowest in Lacerta and La Niña. By selecting a chicory cultivar that has a SL concentration that is acceptable to livestock and ensuring that high levels of P are available to the plants, farmers in Appalachia may successfully include chicory among their forage resources.
Technical Abstract: Chicory (Cichorium intybus L.) is a potentially valuable forage species for Appalachian pastures, but high levels of sesquiterpene lactones (SLs) in the herbage can adversely affect palatability. Because P deficiency has been linked to elevated concentrations of SLs in chicory herbage, investigations were conducted to determine the impact of P fertilization on SL concentrations in chicory cultivars grown in Gilpin silt loam soil having low P availability. The impact of P fertilization differed among cultivars (P < 0.05), but an inverse relationship existed between SL concentration and P fertility (P < 0.01) for initial herbage from plants grown in the greenhouse. Within cultivars, SL concentration was higher in regrowth than in initial herbage (P < 0.001). Whitetail deer, which grazed initial herbage in field plots, avoided ‘Forage Feast’ compared to ‘Grasslands Puna’ (Puna), ‘Six Point’, ‘INIA le Lacerta’ (Lacerta), and ‘La Niña’ (P < 0.05) and avoided herbage in plots with low P fertility compared to plots with medium or high P fertility (P < 0.01). Concentrations of SLs in regrowth herbage of Forage Feast, Six Point, Lacerta, and La Niña were not affected by P fertility. They were highest in Forage Feast (1.19 % DW), intermediate in Six Point (0.74 % DW) and Puna (0.69 % DW), and lowest in La Niña (0.56 % DW) and Lacerta (0.50 % DW) (P < 0.001). Fixation of P by the soil may have been responsible for the absence of a fertility response in regrowth herbage. Selection of a chicory cultivar that has a SL concentration that is acceptable to livestock and application of supplemental P between forage harvests could enhance the opportunity to produce palatable chicory forage in Appalachian pastures.