Heritability of Seed Coat Color in Red Clover (Trifolium

							                    Heritability of Seed Coat Color in Red Clover (Trifolium pratense L.)

                                          Arvid Boe and Robin Bortnem

                                         Department of Plant Science
                              South Dakota State University, Brookings, SD 57007

        Of the more than 200 species of Trifolium, only 17 have bi-colored seeds and are not mottled (Gillett
and Taylor, 2001). Bortnem and Boe (2003) created a color index to describe variation in seed coat color in red
clover. Nijdam (1937) indicated seed coat color was controlled by dominant alleles at two loci, one imparting
color and the other intensity. Variability in seed coat color of red clover as it may relate to agronomic traits has
been of interest for 100 years. Snap bean (Phaseolus vulgaris L.) cultivars with colored seed had better seedling
vigor than those with white seeds (Deakin, 1974). Our objective was to estimate heritability for seed coat color
in red clover.

        Seed coat color was determined (1=yellow to 5=purple) for 2 100-seed samples and an index (CX) was
calculated (Bortnem and Boe, 2003) for about 500 plants in the core collection. A half-sib progeny nursery was
established from 27 plants with CXs near the extremes (i.e., 1 or 5). Seed collected from the progeny nursery
was colorized using CX, and narrow-sense heritability was estimated by regression of progeny mean CX on
selected parent CX. Repeatability for CX was estimated from seed harvested from individual plants in a
genetically broad-based population in 2 consecutive years.

       Repeatability estimates for seed coat color were as high as 0.98, and narrow-sense heritability was
estimated at 0.69 (Fig. 1). This indicated a substantial additive genetic component for seed coat color and rapid
progress from phenotypic recurrent selection for monochrome seed coats.




                    Fig 1. Regression of half-sib progeny mean CX on selected parents CX.

Bortnem, R., and A. Boe. 2003. Color index for red clover seed. Crop Sci. 43:2279-2283.
Deakin, J.R. 1974. Association of seed color with emergence and seed yield of snap beans. J. Am. Soc. Hort.
Sci. 99:110-114.
Gillett,J.M., and N.L. Taylor. 2001. The world of clovers. Iowa State Univ. Press, Ames.
Nijdam, F.E. 1937. Kruisingen met Trifolium pratense L. Genetica 14:161-278.