The effect of an elevated partial pressure of CO2 (pCO2) on carbohydrate concentrations in source leaves and pseudo‐stems (stubble) of Lolium perenne L. (perennial ryegrass) during regrowth was studied in a regularly defoliated grass sward in the field. The free air carbon dioxide enrichment (FACE) technology enabled natural environmental conditions to be provided. Two levels of nitrogen (N) supply were used to modulate potential plant growth. Carbohydrate concentrations in source leaves were increased at elevated pCO2, particularly at low N supply. Elevated leaf carbohydrate concentrations were related to an increased structural carbon (C) to N ratio and thus reflected an increased C availability together with a N‐dependent sink limitation. Immediately after defoliation, apparent assimilate export rates (differences in the carbohydrate concentrations of young source leaves measured in the evening and on the following morning) showed a greater increase at elevated pCO2 than at ambient pCO2; however, replenishment of carbohydrate reserves was not accelerated. Distinct, treatment‐dependent carbohydrate concentrations in pseudo‐stems suggested an increasing degree of C‐sink limitation from the treatment at ambient pCO2 with high N supply to that at elevated pCO2 with low N supply. During two growing seasons, no evidence of a substantial change in the response of the carbohydrate source in L. perenne to elevated pCO2 was found. Our results support the view that the response of L. perenne to elevated pCO2 is restricted by a C‐sink limitation, which is particularly severe at low N supply.

Permanent pastures and meadows are species‐rich vegetation systems that play an important role in the ecology and agriculture of temperate climates. Intensive management reduces species diversity and may also influence the genetic diversity within individual species and populations. The objective of this study was to assess genetic variability of meadow fescue, an important component of species‐rich grasslands, and to determine whether fertilization and defoliation frequency influence genetic variability within natural populations. Genetic diversity of six natural populations and three cultivars of Festuca pratensis was investigated using randomly amplified polymorphic DNA (RAPD) markers and agronomic traits. Samples of natural populations were taken from two unrelated long‐term experiments, where treatments had been applied for 11–38 years. RAPD analysis detected a clear genetic distinction of the cultivars from the natural populations. Genetic variability within cultivars was lower than within natural populations. Analysis of molecular variance (AMOVA) showed a significant effect of management on genetic variability. Fertilization and frequent defoliation led to a reduction in genetic variability within natural populations. Analysis of agronomic traits was only partially congruent with the results of RAPD analysis. This study shows that significant genetic variability exists within cultivars and natural populations of Festuca pratensis and can be reduced by intensive management.

A new yeast species, Bullera piricola, is described. The three strains studied were all isolated from the pear phylloplane. This species differs from all Bullera species known at present by forming symmetrical as well as asymmetrical ballistospores. The problem of its integration into the genus Bullera Derx is discussed. An amended diagnosis of the genus Bullera is given.

Three widely used cultivars of each of the species Festuca pratensis Huds., Lolium perenne L., and Dactylis glomerata L. were investigated by means of randomly amplified polymorphic DNA (RAPD) markers and vegetative growth traits in order to investigate genetic variability within each cultivar and to compare the level of diversity among cultivars and species. RAPD markers allowed a clear separation of the three species. Genetic variability based on RAPD markers was considerably lower for F. pratensis cultivars than for L. perenne and D. glomerata cultivars which showed similar levels of variability. The proportion of variability due to variation within cultivars, determined by an analysis of molecular variance, was lower in F. pratensis (64.6%) than in L. perenne (82.4%) and D. glomerata (85.1%). A comparison of F. pratensis and L. perenne, based on vegetative growth traits, confirmed the differences in genetic variability within cultivars. F. pratensis showed lower coefficients of genetic variation for eight of ten traits when compared to L. perenne. This study demonstrates considerable differences in genetic variability which may have consequences for the adaptability and persistency of individual cultivars.

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