Phenotypic variation and performance of diploid subspecies ofDactylis glomerataL

Dactylis glomerata L. is one of the best known examples of a polyploid complex that includes diploid (2n=14), tetraploid (2n=28) and hexaploid (2n=42) types. The diploids, descending from the ancestors of the genus, are numerous, distinct forms adapted to specific environments and include all the morphological variation and ecological adaptation found in Dactylis. The objective of the present study was to shed more light on the differentiation of diploids and to obtain information for better exploiting the genetic resources of this species. To this end we carried out a discriminant analysis in the most widespread diploid subspecies based on a large number of morpho-physiological traits. We found that some characteristics, such as time to heading, time to flowering, vegetative regrowth, plant height and seed shattering are the most discriminant and enabled us to realize a more exact differentiation of the diploids with respect to the morphological criterion generally adopted. The results demonstrated that diploid taxa offer an interesting combination of relevant agronomical and ecological characteristics which could be useful in breeding programs to promote the use of this species in sustainable agriculture systems. We also performed cytological investigations and defined a general karyotype representative of the diploid Dactylis considered in this study. Dactylis glomerata, polyploidy complex, phenotype, discriminant analysis, genetic resources, karyotype