Manfred Stoll

• Geisenheim University

This article analyzes the economic viability of agrivoltaic (Agri-PV) systems in viticulture based on four scenarios with varying light transmission levels of PV modules. It reveals a trade-off between energy yield and grape production. Only one scenario meets requirements to keep the status as agicultural land but remains economically unprofitable...

This article analyzes the economic viability of agrivoltaic (Agri-PV) systems in viticulture based on four scenarios with varying light transmission levels of PV modules. It reveals a trade-off between energy yield and grape production. Only one scenario meets requirements to keep the status as agicultural land but remains economically unprofitable...

Agri-photovoltaic (Agri-PV) systems may offer a dual-use solution for vineyards facing climate change and rising production costs. At Hochschule Geisenheim, the first German Agri-PV pilot system explores the economic and ecological potential of elevated, semi-transparent solar panels above grapevines. These systems protect against extreme weather,...

Introduction This paper introduces a framework for assessing the economic performance of agrivoltaic systems (AVS) in vineyards. The study aims to classify factors influencing the profitability of integrating photovoltaic (PV) systems with viticultural practices, emphasizing potential synergistic benefits. Focused on the geographic and climatic con...

Grapevine downy mildew caused by Plasmopara viticola is a deleterious vine disease currently controlled using synthetic and copper-based fungicides. Environmental concerns surrounding such fungicides necessitate sustainable alternatives like grape cane extracts. However, studies into their efficacy and effects on the product remain limited. This st...

This study introduced the application of concepts and methods from extreme value theory (EVT) to estimate the probability that daily minimum temperatures exceed springtime critical temperature thresholds for Pinot noir buds and young shoots as a function of springtime phenology. The springtime frost risk estimates were computed spatially for Pinot...

This analysis is a follow-up to a recent study that examined the ripening potential of Pinot noir in Oregon’s Willamette Valley (WV) American Viticultural Area (AVA). The study involved computations of the growing season average temperature (GST) viticulture climate classification index on a mean decadal basis from the 1950s to the 2090s using coup...

Reproducibly comparing the heat stress response of grapevine berries from different cultivars in the field is often limited by weather conditions during the growing season. This work presents a mobile heating device capable of controlled heat-stress induction on grapevine berries. The heater consisted of six 150 W infrared lamps mounted in a profil...

This analysis is a follow-up to two recent studies that separately examined the ripening potential of Pinot noir in Northern California’s Fort Ross-Seaview, Los Carneros, Petaluma Gap, and Russian River Valley American Viticultural Areas (AVAs) and Oregon’s Willamette Valley AVA, respectively. Each study involved computations of the growing season...

In the context of climate change, yield and quality losses from sunburn necrosis are challenging grape growers around the world. In a previous review, we identified the role of wind speed, duration of heat exposure, drought stress and adaptation as major knowledge gaps that prevent a better predictability of sunburn events. In this paper we present...

An unbiased MACA CMIP5 ensemble that optimized calculation of the growing season average temperature (GST) viticulture climate classification index throughout Northern California’s Fort Ross-Seaview (FRS), Los Carneros (LC), Petaluma Gap (PG), and Russian River Valley (RRV) American Viticultural Areas (AVAs) was applied to compute the GST index and...

Atmospheric carbon dioxide (CO2) concentration has continuously increased since pre-industrial times and has currently reached an average growth rate of 2.3 ppm per year. For the majority of plant species elevated CO2 (eCO2) improves photosynthesis and thus plant biomass production. To investigate the effects of eCO2 on leaf physiology and morpholo...

The accessibility to water is a crucial factor for grapevine performance in vineyards. A sufficient supply of water favors vegetative growth, yield formation and fruit ripening. Under a changing climate, especially steep slope wine-growing regions may face severe problems in soil moisture conservation due to oftentimes lower soil water holding capa...

Atmospheric carbon dioxide (CO2) concentration has continuously increased since pre-industrial times from 280 ppm in 1750, and is predicted to exceed 700 ppm by the end of 21st century. For most of C3 plant species elevated CO2 (eCO2) improve photosynthetic apparatus results in an increased plant biomass production. To investigate the effects of eC...

Air temperature is the key driver of grapevine phenology and a significant environmental factor impacting yield and quality for a winegrape growing region. In this study the optimal downscaled CMIP5 ensemble for computing the growing season average temperature (GST) viticulture climate classification index was determined to spatially compute on a d...

Climate change and rising atmospheric carbon dioxide concentration are a concern for agriculture, including viticulture. Studies on elevated carbon dioxide have already been conducted on grapevines, mainly taking place in greenhouses using potted plants or using field-grown vines under instant and higher CO2 enrichment, i.e., > 650 ppm. The Vineyar...

Stilbenoids in grape cane (Vitis vinifera L.) are bioactive compounds relevant for plant defense and the potential valorization of this byproduct. Our screening of grape cane from 102 varieties showed constitutive stilbenoid levels in a wide range (557-7748 mg/kg of dry weight). Analyses of genetically distinct clones of selected cultivars unravele...

Vineyard soils provide a vast range of ecosystem services through their different functions. Conservation and enhancement of soil quality and thus safeguarding of soil functions is one major goal of sustainable viticulture today. Since soil management influences soil functions in multiple ways, it is crucial to evaluate characteristic effects of su...

In this study, we consider the complete archive of the 32 Coupled Model Intercomparison Project Phase 5 (CMIP5) daily Localized Constructed Analogs (LOCA) downscaled historic datasets and their observational data that were used for downscaling and bias corrections to develop an ensemble that optimises calculation of the growing season average tempe...

Grapevine rootstocks can affect the nitrogen (N) status of the grafted plant due to discrepancies in their nutrient uptake and their efficiency in the allocation of assimilates. When N becomes a limiting factor, the production of phenolic compounds in grapes is enhanced as a result of a down-regulation of the flavonoid production pathway. However,...

It is important to continuously monitor the long-term impact of viticultural management practices and assess opportunities for improving the environmental footprint of vineyard operations. This is particularly relevant to the wine industry as growers face disruptive challenges caused by climate change, shortages of labour and escalating production...

Row orientation, among others, is a crucial factor in determining grapevine performance and health status, thus affecting berry components that form the basis of the later wine profile. However, the literature about the impact of changes in row orientation at steep slope sites on grapevine fruit composition as well as the differentiation between ca...

Historically and under cooler climate conditions, steep slope vineyards yielded best quality wines and highest reputation, due to their distinctive microclimate, especially during ripening period. Nevertheless, steep slope vineyard sites primarily suffer from reduced competitiveness leading to abandonment, thus a loss of valuable vineyard sites. Th...

Future climate projections provide an opportunity to evaluate cultivar climate classification and preferred styles of wine production for a wine grape growing region. However, ensemble selection must account for downscaled archive model skills and interdependence rather than be arbitrary and subjective. Relatedly, methods for generalizing climate m...

Die Auswirkungen von Minimalschnittsystemen auf die weinbaulichen Kosten und Flach- und Steillagen werden analysiert. Die Vor- und Nachteile von Minimalschnittsystemen werden diskutiert und in Bezug zum Klimawandel und der Verfügbarkeit von Wasser gesetzt. The cost effect of minimal pruning systems for flat and steep slope viticulture is analysed....

Low-input training systems, such as minimal pruning (MP) and the semi-minimal pruned hedge (SMPH), require less working hours as a result of fewer viticultural process steps and permit a higher degree of mechanisation. However, their effect on viticultural costs and per litre costs on both flat terrain and steep slopes has not yet been analysed. Th...

Low-input training systems such as minimal pruning (MP) and the semi-minimal pruned hedge (SMPH) require less working hours through fewer viticultural process steps and permit a higher degree of mechanisation. However, their effect on viticultural costs and per litre costs in both flat terrain and steep slopes has not yet been analysed. This study...

The training system Semi-Minimal-Pruned Hedge (SMPH) blends features of traditional Vertical Shoot Positioning-type (VSP) trellising systems with the concept of minimal pruning. While saving labor, this training system results in relatively high crop load and a poor leaf area to fruit weight-ratio (LFR), and thus, needs to be able to ripen grapes i...

Challenges of climate change on the future grape and wine production are widely discussed in science and in the wine industry with the goal to maintain a consistent must and wine quality in the future. Therefore, the effect of elevated CO2 (eCO2)—as one of the relevant greenhouse gases jointly responsible for a changing climate—was investigated con...

Sunburn is a physiological disorder that affects the visual and organoleptic properties of grapes. The appearance of brown and necrotic spots severely affects the commercial value of the fruit, and in extreme cases, significantly decreases yield. Depending on the severity of the damage and the driving factors, sunburn on grapes can be classified as...

Carbon dioxide (CO2) as one of the main factors driving climate change is known to increase grapevine growth and yield and could, therefore, have an impact on the fruit quality of vines. This study reports the effects of elevated CO2 (eCO2) on berry development and bunch structure of two grapevine cultivars (Vitis vinifera L. cvs. Riesling and Cabe...

Optical leaf sensing of plant nitrogen (N) status enables fertilisation based on plant demand. The aim of this study was to assess the suitability of leaf reflectance indices and of a handheld device for the estimation of N and chlorophyll (Chl) in Vitis vinifera L. cv. Riesling. Riesling leaves from a long‐term fertilisation trial were analysed fo...

Removal of basal leaves early in the vegetative and reproductive development of grapevines is a tool used to decrease fruit set, lower cluster rot severity, and improve fruit quality. However, the considerable time required for implementation limits its use by grapegrowers. Efficient mechanization can potentially mitigate these issues, albeit this...

Aim: The effects of integrated, organic and biodynamic management on soil quality and the growth and morphological development of Riesling grapevines were assessed during the first 4 years of a long-term field trial in Geisenheim, Germany. The overall aim was to understand the effects of these different viticultural practices on soil quality and pl...

Background and aims: Measurement of grapevine size is necessary to assess carbon reserves at the level of individual vines and to estimate the carbon sequestration potential of vineyards. Methods of measurement rely mostly on traditional dendrological techniques that may be prone to error. In this study, we examined the use of structure-from-motion...

The occurrence in Riesling wine of the potent odorant 1,1,6-trimethyl-1,2-dihydronapthalene (TDN) is dependent on vineyard and winemaking conditions, and TDN can have a prominent impact on a wine’s attributes after years in bottle. As such, immediately assessing the impact of vineyard or winery treatments on future TDN formation requires forced cre...

Aims: Microscopic bud dissection is commonly used to assess grapevine bud fertility and thereby predict yield for the following season. Grapevine yield has been shown to increase in response to elevated carbon dioxide concentration (eCO2), and this yield gain has been demonstrated under Free Air Carbon dioxide Enrichment (FACE). However, the effect...

Aim: This research was undertaken in the context of climate change and understanding how rising temperatures may interact with viticultural practices, used to manage fruit exposure in Riesling. An experimental system was designed to passively warm the bunch zone and separate the factors, heat and indirect heat by solar radiation. Methods and result...

Aims: A better understanding of the relationship between weather conditions and wine quality would provide tools for assessing the impact of climate change and the potential for adaptation. Most studies rely on assessing wine quality by the price per bottle or by an overall ranking and then establishing general relations to weather conditions. Howe...

Grapevines are perennial plants that can display remarkable longevity. It is often thought that some of their characteristics evolve in a positive way as they grow older, such as having a higher tolerance to water deficit and an improved balance between vegetative and reproductive growth. However, only a few studies have been conducted so far on th...

Two Vitis vinifera L. cultivars, Riesling and Cabernet Sauvignon, were grown in the Geisenheim VineyardFACE (Free Air Carbon dioxide Enrichment) system under rain-fed conditions to investigate the effects of elevated CO2 on the productivity of grapevines for three consecutive years (2014–2016) following planting in 2012. The FACE system consisted o...

The potential influence of fruit exposure and canopy manipulations on grape berry composition is well recognized. However, a simple and low cost method for quantifying the amount of light reaching the fruiting zone is lacking. The objective of the present study was to test the application of a commercial system of photosensitive azo-dye coated plas...

Background and Aims The main objective of the study was to test if differences in leaf composition induced by the rootstock could be detected through non‐invasive fluorescence sensor technology. Methods and Results Multiplex Research measurements on three dates over three consecutive growing seasons showed that Pinot Noir (Vitis vinifera L.) graft...

Two main challenges of a changing climate are the increase in atmospheric carbon dioxide (CO2) and temperature in relation to physiological responses and yield performance of plants. To investigate responses of field grown grapevines under elevated CO2 (+20 %) conditions a FACE (Free Air Carbon dioxide Enrichment) facility for Vitis vinifera cvs. R...

Non-destructive, reliable, fast and automated plant-based methods for the assessment of the water status of a grapevine are necessary to design irrigation strategies. The goal of this work was to test the capability of near infrared (NIR) spectroscopy using a vehicle-mounted and remote NIR sensor without plant contact (contactless) to assess the wa...

Protein haze in white wines is a major technological and economic problem for the wine industry. In particular, an increased haze formation can be observed in wines from dry vintages. Therefore, field tests were carried out in steep slope vineyards planted with Riesling grapes over three dry growing seasons to study the effect of drought stress on...

Insolation of grape bunches has long been postulated to enhance the flavour of aromatic grape cultivars. This hypothesis was tested by combining gene expression and metabolic analysis of the monoterpene and flavonol synthesis pathways. Grape bunches were shaded or shaded and reilluminated to investigate the influence of light on the monoterpene and...

Two main challenges of a changing climate are the increase in atmospheric carbon dioxide (CO2) and temperature in relation to water relations of plants. To investigate responses of field grown grapevines under elevated CO2 conditions a FACE (Free Air Carbon dioxide Enrichment) facility for Vitis vinifera cvs. Riesling and Cabernet Sauvignon was est...

Benefits of increasing CO2 levels have been well investigated for various crops under greenhouse environment. To research perennial plants, especially field grown grapevines under elevated CO2 conditions a FACE (Free Air Carbon dioxide Enrichment) facility for Vitis vinifera cvs. Riesling and Cabernet Sauvignon was established (50°N, 8°E, Germany)....

Bottle-aged Riesling is often characterised by petrol and kerosene-like aromas. While well-accepted when in balance with other aged characteristics for their contribution to complexity, such aromas are considered undesirable in young Riesling wines. This following article highlights possible targets in the grapegrowing and winemaking process to tac...

The main objective of this study was to determine growth, yield and fruit quality of grapevines under organic and biodynamic management in relation to integrated viticultural practices. Furthermore, the mechanisms for the observed changes in growth, yield and fruit quality were investigated by determining nutrient status, physiological performance...

As the concentration of atmospheric carbon dioxide (CO2) is steadily increasing this will have considerably effects on agricultural crops including viticulture. To examine plant responses at future CO2 concentrations under field conditions an open “Free Air Carbon dioxide Enrichment” (FACE) facility for special crops (viticulture and vegetables) wa...

Beside the resistance against phylloxera the adaptation of rootstocks to different site properties e.g. soil pH, water availability,nutrition supply, lime content or salinity and management system of the vineyard are of major importance establishing a vineyard and balancing growth. Pinot Blanc (Vitis vinifera L.; clone Gm 2) were planted in 2003 at...

Ein Herauszögern des Termins des ersten Laubschnitts ermöglicht ein längeres Aufrechterhalten der Assimilatkonkurrenz zwischen den jungen Trauben und der Triebspitze. Dies induziert durch die reduzierte Assimilatversorgung der Blüte- und Zellteilungsvorgänge eine lockerere Traubenstruktur und, damit einhergehend, eine verzögerte Fäulnisepidemie, ei...

Field trials investigating the impact of the timing of first shoot topping in a vertical shoot positioning (VSP) trellis system on (i) the cluster morphology, (ii) the canopy structure in the cluster-zone, and (iii) the progress of the bunch rot disease severity, were conducted in two white Vitis vinifera (Pinot gris, Riesling) cultivars in the yea...

Many cool climate grape vine growing regions are and will be affected by the global climate change. It is likely that increasing temperatures, as well as changing precipitation pattern will impact the wines’ composition and wine styles. In the last decades the sensory concept of German Riesling wines was considered to represent fresh and fruity not...

Microclimate and irradiation have long been known to influence winegrape (Vitis vinifera) quality. However, microclimate influence on white grape quality has remained understudied, as most research efforts have focused on red varieties and their anthocyanin content. In this study, we investigated microclimatic effects on the phenolic and amino acid...

Background and AimsGrape berry growth and composition depend on complex interactions between the genotypes of the rootstock and the scion, vineyard management and environmental factors. The present work aimed to characterise the effect of rootstock genotype and water deficit on the primary and secondary metabolism of the grape berry.Methods and Res...

Grapevine (Vitis vinifera L.) expresses different responses to water stress, depending not only on genotype, but also on the influence of vineyard growing conditions or seasonality. Our aim was to analyse the effects on drought response of two grapevine cultivars growing on two soils, one water draining (WD) containing sand 80% volume and the other...

Leaf area index (LAI) and canopy structure are important parameters affecting grape quality and yield of grapevines. Two different experimental protocols as well as the average LAI value of the different protocols for indirect estimation of LAI by gap fraction analysis in VSP-trained grapevines (Vitis vinifera L. cv. Riesling) were tested in this s...

Grape berry components are important because they determine the quality of the grape and are the most important parameter for the quality of wine. These components depend on a complex interaction between two genotypes (rootstock and scion) and other environmental factors. Climate change affects the physiology of the vine, yield and fruit compositio...

The aim of this study was to validate and implement different non-destructive methods of leaf area and leaf area index (LAI) determination in VSP trained grapevines (Vitis vinifera L. cv. Riesling) in a field trial comparing different management systems (i.e. integrated (GAP) and two different organic (European Union Regulation 834/07) management s...

The increasing temperatures, caused by the global change, lead to an earlier onset of developmental stages, changes in productivity and physiology of different crops and will challenge the growers in the future. Depending on the seasonal conditions the onset of flowering is approximately 10 days earlier compared to the long term average and the rip...

The ratio of Leaf Area to Fruit Weight was investigated into its effects on 'Riesling', and whether changing the ratio could delay its maturation. Leaf Area was reduced using various manual as well as machine defoliation treatments post-flowering, differing in their position of leaf removal and their intensity. Also, application of anti-transpirant...

Producer and consumer demand for improved wine quality has driven substantial amendments in the application of good agricultural practices. To enable high quality production, removal of leaves within the bunch zone has become common practice to enhance sunlight exposure to the cluster zone. Therefore, bunches as target areas are now better exposed...

Grapevine < is a perennial crop often cultivated by grafting a scion cultivar on a suitable rootstock. Rootstocks influence scions, particularly with regard to water uptake and vigor. Therefore, one of the possibilities to adapt viticulture to the extended drought stress periods is to select rootstocks conferring increased tolerance to drought. How...

Grape berry components are important because they determine the quality of the grape and are the most important parameter for the quality of wine. These components depend on a complex interaction between two genotypes (rootstock and scion) and other environmental factors. Climate change affects the physiology of the vine, yield and fruit compositio...

The rapidly increasing world population and the scarcity of suitable land for agricultural food production together with a changing climate will ultimately put pressure on grape-producing areas for the use of land and the input of resources. For most grape-producing areas, the predicted developments in climate will be identical to becoming more mar...

Remote detection using thermal imagery has potential for use in the pre-symptomatic diagnosis of abiotic stress or of early disease detection. The latter is an issue of great importance since late detection of fungus attacks or poor spray coverage are major factors contributing to weak disease control affecting fruit quality or reducing yield in gr...

The effect on spatial variability of leaf temperature of inoculating grapevine leaves (Vitis vinifera L. cv. Riesling) with a fungal pathogen (Plasmopara viticola) was studied in either well irrigated or non-irrigated plants. The results from thermal imagery were compared with stomatal conductance measured by leaf gas exchange. The high sensitivity...

Aims: The objective of this paper was to describe an approach to the use of thermal data for shaded leaves rather than areas fully exposed to the sun. Secondly to make use of infrared thermography as a powerful tool to measure effects of solar radiation on berry temperature. Methods and results: Thermal images were obtained with a long-wave thermal...

Pot experiments with split-root plants and two years of field experiments with manipulation of soil water content have shown that partial rootzone drying (PRD) does not affect yield in raspberries, Rubus idaeus L. 'Glen Ample' and 'Glen Prosen'. In some cases PRD can reduce stomatal conductance, thus reducing water loss. This results in a higher wa...