In diverse plant communities the relative contribution of species to community biomass may change considerably in response to elevated CO2. Along with species‐specific biomass responses, reproduction is likely to change as well with increasing CO2 and might further accelerate shifts in species composition. Here, we ask if, after 5 years of CO2 exposure, seed production and seed quality in natural nutrient‐poor calcareous grassland are affected by elevated CO2 (650 μL L−1 vs 360 μL L−1) and how this might affect long‐term community dynamics. The effect of elevated CO2 on the number of flowering shoots (+ 24%, P < 0.01) and seeds (+ 29%, P = 0.06) at the community level was similar to above ground biomass responses in this year, suggesting that the overall allocation to sexual reproduction remained unchanged. Compared among functional groups of species we found a 42% increase in seed number (P < 0.01) of graminoids, a 33% increase (P = 0.07) in forbs, and no significant change in legumes (− 38%, n.s.) under elevated CO2. Large responses particularly of two graminoid species and smaller responses of many forb species summed up to the significant or marginally significant increase in seed number of graminoids and forbs, respectively. In several species the increase in seed number resulted both from an increase in flowering shoots and an increase in inflorescence size. In most species, seeds tended to be heavier (+ 12%, P < 0.01), and N‐concentration of seeds was significantly reduced in eight out of 13 species. The fraction of germinating seeds did not differ between seeds produced in ambient and elevated CO2, but time to germination was significantly shortened in two species and prolonged in one species when seeds had been produced in elevated CO2. Results suggest that species specific increases in seed number and changes in seed quality will exert substantial cumulative effects on community composition in the long run.

The effects of organic and integrated production systems on the culturable fungal microflora of stored apple fruits from five matched pairs of certified organic and integrated 'Golden Delicious' farms were studied at five representative production sites in Switzerland. Isolated fungi were identified morphologically. Colonization frequency (percentage of apples colonized), abundance (colony numbers), and diversity (taxon richness) were assessed for each orchard. The standard quality of the stored fruits was comparable for both organic and integrated apples and complied with national food hygiene standards. Yeasts (six taxa) and the yeast-like fungus Aureobasidium pullulans were the dominant epiphytes, filamentous fungi (21 taxa) the dominant endophytes. The most common fungi occurred at all sites and belonged to the "white" and "pink" yeasts, yeast-like A. pullulans, filamentous fungi Cladosporium spp., Alternaria spp., and sterile filamentous fungi. Canonical correspondence analysis of the total fungal community revealed a clear differentiation among production systems and sites. Compared to integrated apples, organic apples had significantly higher frequencies of filamentous fungi, abundance of total fungi, and taxon diversity. The effects of the production system on the fungal microflora are most likely due to the different plant protection strategies. The incidence of potential mycotoxin producers such as Penicillium and Alternaria species was not different between production systems. We suggest that higher fungal diversity may generally be associated with organic production and may increase the level of beneficial and antagonistically acting species known for their potential to suppress apple pathogens, which may be an advantage to organic apples, e.g., in respect to natural disease control.

The impact of soil type, long-term soil management, and short-term fertility input strategies on the suppressiveness of soils against soil-borne (Ocimum basilicum -Rhizoctonia solani, Lepidium sativum -Pythium ultimum) as well as air-borne (Lycopersicon esculentum -Phytophthora infestans, Arabidopsis thaliana -Hyaloperonospora parasitica) diseases was studied. Soils from field trials established in five European sites with contrasting pedoclimatic conditions were examined. Sites included (i) a long-term management field trial comparing organic and conventional farming systems (DOKtrial, Therwil, Switzerland) (ii) a short-term fertility input field trial comparing mineral and organic matter fertilisation regimes (Bonn (BON), Germany) (iii) two short-term fertility input field trials (Stockbridge (STC) and Tadcaster (TAD), UK) comparing the impact of farmyard manure, composted farmyard manure, and chicken manure pellet amendements and (iv) soil from a site used as a reference (Reckenholz (REC), Switzerland). Soil type affected disease suppressiveness of the four pathosystems signficantly, indicating that soils can not only affect the development of soil-borne, but also the resistance of plants to air-borne diseases at relevant levels. Suppressiveness to soil-and air-borne diseases was shown to be affected by soil type, but also by long-term management as well as short-term fertility inputs.

Air-borne foliar diseases as well as soil-borne diseases can cause substantial losses in agricultural production systems. One of the strategies to overcome production losses caused by plant diseases is the targeted use of disease defence mechanisms that are inherent to plants. In this paper, the potential to enhance the plant's health status either by inducing resistance through optimized soil management techniques or by foliar application of inducers of resistance is explored on the basis of a literature review and results from laboratory and field experiments. In our studies, the focus was on recent research about the use of dl-␤-aminobutyric acid (BABA) and an aqueous extract of Penicillium chrysogenum (Pen) as elicitors. We conclude that BABA as well as Pen can contribute to disease control strategies. The use of soil fertility management techniques to reduce diseases was explored in recent research about the impact of shortand long-term management practices on soil suppressiveness to air-borne and soil-borne diseases, with the aim to elucidate the influence of soil properties and to quantify the relative importance of site-specific vs cultivation-mediated soil properties. The results indicate that site-specific factors, which cannot be influenced by agronomic practices have a greater impact than cultivation-specific effects within the same site. Nevertheless, short-and long-term management strategies were shown to have the potential for influencing soil suppressiveness to certain diseases such as Rhizoctonia solani.

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