Evaluacion de la variabilidad morfologica, agronomica e isoenzim tica en poblaciones del pais de Raigr s italiano (Lolium multiflorum Lam.).
1995
Bregu R.
Variability of 19 land races of Italian Ryegrass from Galicia and Asturias, was evaluated with the aim of introducing this germplasm in selection and breeding programmes and to define a strategy of genetic resources conservation of this important forage crop. Agronomic and morphological characterization showed a great variability. Populations for most of the characters showed more variability than controls. Seedling characters were correlated themselves but not with adult plant characters. Principal Component Analysis explained more than 64 per cent of total variation with only three components. Heading date, length of the inflorescence, dry matter yield and seedling character were the most discriminants. A hierarchical ascendant clustering on different agronomic traits leads to 4 clusters of populations. Genetic parameters evaluated by isozyme markers (11 loci) on 10 populations, confirmed the existence of a great genetic variability. The mean expected heterozigosity (0.451) and average number of alleles per locus (3.3) resulted to be higher than those obtained by other authors. Populations deviated most of the Hardy-Weinberg equilibrium on GOT-3 and ACP-2 loci. Values of Nei's distance and their F statistics showed a low level of differentiation between populations (4.2 per cent) and a high level of differentiation within population (96 per cent). Classification obtained with the isozyme data, showed that populations seemed to group in the same cluster, except two of them that seemed to be commercial varieties. Groups obtained from agronomic data, did not show common genetic characteristics, this implies the conservation and multiplication of the groups independently. A family-individual combined selection programme was begun in a population which showed an early heading date and high dry matter yields in early winter. The aim is to include this material as first culture in rotation with maize.
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