Genetic differences between natural populations of diploid and tetraploid Dactylis glomerata ssp. izcoi

Twenty-one natural populations (thirteen tetraploids and eight diploids) of Dactylis glomerata ssp. izcoi (an Iberian endemic) were evaluated in the held for three consecutive years, using two clones per genotype, to separate genetic and environmental factors. Many traits showed significant differences between ploidy levels, but all of them overlapped. Therefore, it is justified to include both cytotypes in a subspecies in which tetraploids could be autopolyploids. In general, however, diploids had shorter stomatal guard cells, lower seed production and were later heading than tetraploids. Within tetraploids, most traits differed significantly between and within populations. There was less inter- and intrapopulation variation in the diploids. The range of plant dimensions exceeded that of former descriptions of the sub-species, bringing it closer to ssp. glomerata. Inland populations were not qualitatively different from one coastal population. Diploid populations showed less risk of hypomagnesemia than tetraploids.