An active and diverse soil biota is important for maintaining crop productivity and quality, and preservation of these traits is a major goal of sustainable farming. This study aimed at unravelling the impact of different management practices on soil fungal and bacterial biodiversity in vineyards as a model for permanent crops. Species diversity was assessed using an amplicon sequencing approach in a long-term field experiment in the Rheingau wine region of Germany where integrated, organic and biodynamic management practices had been in place for 10 years. Fungal community composition under integrated management differed significantly from organic and biodynamic management, whereas fungal species richness remained unaffected. Soil under integrated management had a significantly reduced bacterial species richness compared to organic, but community composition was similar to organically and biodynamically managed soils. Highest fungal richness was obtained under cover crop between rows in topsoil, arising from cover cropping and organic carbon supply.

Nitrogen (N) remobilization in the context of leaf senescence is of considerable importance for the viability of perennial plants. In late-ripening crops, such as Vitis vinifera, it may also affect berry ripening and fruit quality. Numerous studies on the model plant Arabidopsis thaliana have confirmed an involvement of the plant hormone ethylene in the regulation of senescence. However, ethylene research on grapevine was mostly focused on its involvement in berry ripening and stress tolerance until now. To investigate the effect of ethylene on the initiation, regulation, and progress of senescence-dependent N mobilization in grapevine leaves, we treated field-grown Vitis vinifera cv. Riesling vines with 25 mM ethephon at the end of berry ripening. Ethephon induced premature chlorophyll degradation and caused a shift of the leaf transcriptome equivalent to developmental leaf senescence. The upregulated metabolic processes covered the entire N remobilization process chain, altered the amino acid composition in the leaves, and resulted in an average 60% decrease in leaf N. Our findings increase the fundamental knowledge about the initiation and manipulation of leaf N remobilization in perennial woody plants by ethephon. This offers a methodological approach to the targeted induction of senescence and thus to an improvement in the N supply of grapes.

Vineyard soils show an increased risk of degradation due to being intensively cultivated. The preservation of soil integrity and fertility is a key concept of organic and biodynamic farming. However, both systems are also subject to criticism due to their higher amount of plant protection products used and their increased traffic intensity compared to integrated viticulture, both detrimental to soil quality. The aim of this study was therefore to assess long-term effects of these three management systems on chemical and physical soil quality parameters. For this purpose, topsoil samples were taken in a long-term field trial vineyard at different positions and examined for bulk density, available water capacity (AWC), soil organic carbon (SOC), N, pH, and for total and bioavailable copper (Cu) concentrations. Biodynamic plots had a lower bulk density and higher SOC concentration than the integrated ones, which is probably due to the species-rich cover crop mixture used in the inter-row. However, organic and biodynamic farming showed an accumulation of copper in the under-vine area and in the tractor track, which is problematic for soil fertility in the long-term. Therefore, alternatives for copper in plant protection are necessary to ensure sustainable soil quality through organic and biodynamic viticulture.

Background and Aims Leaf senescence induces a massive shift of the nitrogen (N) allocation within plants, but its influence on the storage of yeast-assimilable N (YAN) in grapevine berries is unclear. The aim of this work was to investigate whether the YAN concentration in grape must can be increased by a targeted induction of leaf senescence. Methods and Results Leaf senescence was induced in two consecutive seasons by an ethephon treatment of grapevines (Vitis vinifera cv. Riesling) before harvest, and its effect on the amino acid and ammonium balance of berries and must, as well as on alcoholic fermentation performance was investigated. The ethephon-induced senescence caused a significant increase in YAN concentration in berries and must, based on a general increase in most amino acids. Compared to natural senescence, the ethephon treatment led to a lower proline : arginine ratio, a lower sugar concentration in the must and a lower grape yield. Conclusions Ethephon-induced leaf senescence enhances the nutritional value of grapes and improves the fermentability of grape must. Significance of the Study Our results enable wine producers to improve the nitrogen use efficiency of vines and to ensure a balanced N nutrition of the yeast.