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Title: SEASONAL VARIATIONS IN CONDENSED TANNINS CONCENTRATION OF THREE LOTUS SPECIES

Author
item GEBREHIWOT, L - UNIV OF MISSOURI-COLUMBIA
item BEUSELINCK, PAUL
item ROBERTS, C - UNIV OF MISSOURI-COLUMBIA

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2002
Publication Date: 9/1/2002
Citation: GEBREHIWOT, L., BEUSELINCK, P.R., ROBERTS, C.A. SEASONAL VARIATIONS IN CONDENSED TANNINS CONCENTRATION OF THREE LOTUS SPECIES. AGRONOMY JOURNAL. 2002. V. 94(5). P. 1059-1065.

Interpretive Summary: Trefoil is a common name applied to three related Lotus species grown for forage in pastures of the United States. Trefoil can produce phenolic compounds called condensed tannins (CT) that can be beneficial or detrimental to grazing animals, depending upon the amount produced. It is known that a small amount of CT can improve protein utilization by grazing animals, while large amounts can inhibit protein availability and can inhibit feeding. In this study, we examined CT production in three widely grown Lotus species to: i) determine the effect of seasons; ii) determine the distribution in leaves, stems, and flowers; and iii) determine if greenhouse-grown plants exhibit equivalent ranking to field-grown plants. Experiments conducted in the field demonstrated that CT concentrations were greatest in spring and summer and least in fall for birdsfoot trefoil (Lotus corniculatus L, cvs. ARS-2620 and Norcen) and big trefoil (L. uliginosus Schkur., ARS-1207 germplasm), while narrowleaf trefoil (Lotus glaber, ARS-1221 germplasm) was low in CT. The forage of big trefoil had very high CT levels and birdsfoot trefoil was moderately low. Leaves and flowers were higher in CT than stems. The rankings of the four entries for forage CT concentration in the greenhouse and field were the same. It was concluded that the CT concentrations of big trefoil were high enough to be detrimental to protein availability and palatability by grazing animals, while levels in narrowleaf trefoil may be too low to benefit protein utilization. This information is important to researchers attempting to understand the genetic relationship among these trefoil species and to other plant scientists studying the ecology of these birdsfoot trefoil species in interactions with animals, insects, and diseases.

Technical Abstract: Condensed tannins (CT) are commonly found in herbage of Lotus species and can have beneficial or detrimental effects on feed value and animal performance. Our objectives were: i) to determine the level of CT concentration and its seasonal variations in three widely grown Lotus species; ii) to assess the distribution of CT in leaves, stems and flowers; ;and iii) to determine if herbage of greenhouse-grown Lotus species contain CT concentrations with equivalent rank to field-grown plants. Herbage of big trefoil (L. uliginosus Schkur.) germplasm ARS-1221 and narrowleaf trefoil (L. glaber Mill.) germplasm ARS-1207 had the greatest and lowest CT concentrations averaging 154 and 8 g catechin equivalent (CE)/kg DM, respectively. The birdsfoot trefoil (Lotus corniculatus L.) cv. ARS-2620 had a greater CT concentration than 'Norcen', but both had moderate CT levels averaging 39 and 23 g CE/kg DM, respectively. Herbage CT concentration of Norcen, ARS-2620, and ARS-1221 were higher in spring and summer as compared to fall, while ARS-1207 CT was low in spring, summer, and fall. Generally, stems had less CT than leaves and flowers, but there was no detectable CT in stems of ARS-1207. The rankings of the four entries for herbage CT concentration in the greenhouse and field were the same. This is the first report of CT concentrations for the germplasms, ARS-1221, and ARS-1207, which are suitable candidates for genetic improvement to develop cultivars with desirable CT levels. Greenhouse screening for CT concentration can be used for these three Lotus species.