Indicators for genetic and phenotypic diversity of Dactylis glomerata in Swiss permanent grassland

Genetic diversity is the fundamental level of biological diversity. In the discussion of biological diversity in agricultural ecosystems, this level is of major importance, but often neglected. Tools for the direct measurement of genetic diversity, especially in highly diverse systems such as permanent grassland, are demanding and the relationship between genetic diversity and management practices or environmental factors is poorly understood. Genetic diversity of the common grassland species Dactylis glomerata was assessed using genetic diversity indices based on 29 SSR markers. Phenotypic diversity within and among selected populations was evaluated in a replicated field experiment based on ten phenotypic plant characters of agronomic relevance. Twenty populations of D. glomerata from permanent grassland from the Swiss Alps were included in the analysis. We investigated correlations between genetic diversity (genotypic/phenotypic) and farming system (conventional/organic), management intensity (intensive/extensive), three plant species diversity indices, five ecological and five habitat parameters at collection sites. Genetic and phenotypic variability within and among populations of D. glomerata was large. The intensive management of permanent grassland reduced genotype diversity and genetic variation of the plant character 'flowering time', while conventional farming systems increased the average expected heterozygosity within populations of D. glomerata. Populations from extensively managed sampling sites accommodated significantly smaller D. glomerata individuals. SSR markers and phenotypic characters proved to be valuable tools for the assessment of genetic and phenotypic diversity considering different perspectives. Management parameters were the main factors influencing genotypic diversity and phenotypic characteristics in natural populations of D. glomerata in permanent grassland.