Change of Ryegrass Seedling Root Fluorescence Expression during Three Generations of Seed Increase
- Donald J. Floyda and
- Reed E. Barker *b
Seedling root fluorescence (SRF) has been used since the early 1940s to discriminate Italian (annual) ryegrass (Lolium multiflorum Lam.) from perennial ryegrass (L perenne L.). Generally, roots of Italian ryegrass fluoresce under ultraviolet light, while those of perennial ryegrass do not fluoresce, but the trait has readily introgressed from Italian to perennial. Breeders document fluorescence levels of new ryegrass cultivars before they enter seed certification programs. The objective of this study was to ascertain if there was genetic change for the expression of SRF during generations of seed multiplication. Four ryegrass populations, constructed to have low, medium, and high SRF levels, were increased independently for three generations in the field at each of three Oregon locations (Aurora, Corvallis, and Madras). The SRF was measured on the initial population parents, and for each generation cycle at each location. There were significant differences in SRF among locations within populations and for seed production generation within locations. One population initially at 11% SRF increased to 36% across the three generations of seed multiplication at Corvallis, but decreased to 8 and 2% at the other two locations. The other three populations responded differently, showing large population × location and population × generation interactions for SRF expression. Location of increase and the seed production generation must be examined and carefully considered when describing fluorescence levels of cultivars for seed certification purposes. The large amount of variation associated with environmental influences indicates SRF is not a reliable characteristic to describe and predict ryegrass cultivar genetic purity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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