Taxonomic Investigation of an Accession of Lotus spp.1

Abstract

The large seeded plant introduction (PI) 302921 (MO accession 266) was obtained with the tentative identity as a Lotus tenuis Waldst. & Kit., but preliminary observations of its morphology, except for seed size, were more characteristic of the phenotype described for L. corniculatus L. Our objective was to make morphologic, karyotypic, and idiographic comparisons of entry 266 with four randomly chosen L. tenuis introductions, (MO accessions 250, 253,256, 260) and two L. corniculatus cultivars, ‘Dawn’ and ‘Norcen’, grown in greenhouse and field environments to reidentify entry 266. Entries of L. corniculatus and L. tenuis conformed to taxonomic keys based on morphological characters including leaf length, width, area, length/width ratio, and chromosome number. Entry 266 consistently exhibited small leaf characteristics and leaf pubescence. Leaf length/ width ratio appeared to be the most reliable morphological character for taxonomic placement of entry 266, which was similar to the L. corniculatus entries in this study and previous reports of L. corniculatus morphology. Entry 266 was found to have a somatic chromosome number of 2n=4x=24 and a karyotype and idiogram similar to the L. corniculatus entries. Hybrids obtained from reciprocal crossings among genotypes of the L. corniculatus germplasm, MO‐20, and entry 266 exhibited a relatively high degree of fertility. A higher percentage of abnormal pollen observed in the F1 hybrid was not significantly higher than that of the parents or the first cycle of the randomly mated L. corniculatus population, MU‐81. Geographical isolation of the parents might account for the slightly higher pollen abnormalities in the F1 hybrids. Findings indicate PI 302921 to be a L. corniculatus accession of value for its large seed character.