Ryegrasses are the third most important forage grasses grown in Argentina.
Commercial seed lots of Lolium perenne L. (perennial ryegrass) are generally contaminated with
seeds of Lolium multiflorum Lam. (annual ryegrass), which diminish their agronomic and economic
values. The rapid identification of the species by morphological observation of the seeds is very
difficult. Fluorescence test in seedling root is usually used in Seed Testing Labotatories in our
country. But this test presents limitations since not all the ryegrass cultivars, nor all the hybrids
between these species, show the same reaction under ultra violet light. Vernation, however, is a
useful character to differentiate the two species at seedling stage. This study determined the seed
quality in commercial samples of perennial ryegrass and the reliability of fluorescence test to
identify them, contrasting their results with those of leaf vernation test. Eighty nine samples of
commercial seed lots of perennial ryegrass were analyzed according to: purity analysis, standard
germination and fluorescence test and vernation analysis in seedlings. Forty eight percent of the
samples complied with the levels officially established for all the quality parameters. In the
identification of perennial and annual ryegrass, the agreement between both tests was of 81%.
Vernation test should offer more reliable results that fluorescence test in identification of ryegrass
species; it is suggested its use on its own or as alternative proccedure to fluorescence test.