Foliar condensed tannin levels in lotus species growing on limed and unlimed soils in South-Eastern Australia

Abstract

Condensed tannin concentrations (% of dryweight) were measured in leaves of 22 accessions of Lotus corniculatus, 10 accessions of L. pedunculatus, 2 accessions of L. tenuis, and 1 accession of L. subbiflorus from plants growing on limed (pH = 5.2) and unlimed (pH = 4.3) soils near Canberra, A.C.T. There was a non-significant decrease in the mean condensed tannin concentration due to liming. The differences between species and between accessions within species were significant. For the L. corniculatus entries the range of tannin concentrations over the limed and unlimed sites was 0.15-7.28%, with a mean of 2.09%. The highest concentration was found in the otherwise promising accession CPI 66414. L. pedunculatus accessions ranged from 2.53-10.72% in tannin content, with a mean of 5.99%. Two Portuguese accessions that have promising agronomic features for coastal east Australian pastures had unacceptably high tannin levels above 7.50%. Genotypic differences accounted for a large proportion of the total variability for tannin production, so there are good prospects for the improvement of these species by selection and breeding. Keywords: Lotus corniculatus, L. pedunculatus, L. tenuis, L. subbiflorus, condensed tannins