Ces travaux visent à comprendre de quelle manière l’appropriation peut amener au développement d’une compétence distribuée entre l’homme et la technologie. Nous nous sommes penché sur un terrain d’étude particulier, celui de la viticulture de précision, terme désignant l’ensemble des technologies permettant de caractériser l’hétérogénéité spatiale et temporelle des parcelles et de moduler les pratiques viticoles en fonction des besoins de la vigne. Nous avons réalisé une revue de littérature ainsi que des entretiens semi-directifs pour aboutir à une analyse qualitative intra-cas et inter-cas de sept cas différents.Ce travail s’appuie sur cinq propositions de recherche : 1) La compétence est un processus dynamique jugé socialement et mis en œuvre durant l'activité d'un sujet qui combine ses ressources internes avec des ressources externes issues d'un contexte dans le but d'atteindre une finalité, de réaliser une tâche.2) La compétence est composée des ressources internes et externes, mais aussi d’une structure (pattern) permettant de les coordonner. 3) La technologie, par le biais de la notion d'instrument composé d'un artefact et de schème, peut apporter des ressources et une structure nécessaires à la mise en œuvre de la compétence. 4) Grâce à l'appropriation. Elle se réalise de deux manières, l'instrumentalisation fait évoluer les ressources physiques de l'instrument. L'instrumentation permet le développement d'une structure distribuée, qui va coordonner les ressources internes et les ressources de l’environnement avec les ressources apportées par l'instrument. 5) L'appropriation souligne l'aspect d'une compétence à la fois distribuée socialement, dans le temps, et entre l'homme et la technologie. Cette compétence peut être déclinée au niveau individuel, collectif ou organisationnel. / The aim of this work is to understand how appropriation of technology can develop a competence distributed between human and technology. We examine a particular field of study, that is precision viticulture technology. These technologies allow to characterize spatial and temporal heterogeneity of plots and to modulate wine-making practices according to vine’s needs. We have made a state of the art and some semi-structured interviews to lead to an individual and cross cases analysis of seven cases.This work rely on five research proposals: 1) Competence is a dynamic process which depend of a social judgment, carried out during activity by a subject who combine his internal resources with external and contextualized resources in order to reach an aim, realize a task.2) Competence is composed by internal and external resources of a subject and by pattern which allow to coordinate them. 3) Technology, by the way of the concept of instrument, composed by artifact and scheme can provide resources and pattern needed to competence’s implementation. 4) This can be possible thanks to appropriation, by two ways. Instrumentalization changes resources of instrument and instrumentation allows development of distributed structure which coordinates resources. 5) This highlight the socially and temporal distribution of competence and the distribution between human and technology. This distribution is possible at individual level, collective level and organizational level.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2009. / South Africa is the eighth largest wine producing country in the world and face stiff competition on the world market. Cabernet Sauvignon is the most planted red cultivar in the world as well as in South Africa and can be seen as the wine by which countries are judged. The aim of this study was to investigate suitable, practical maturity parameters or combinations thereof to determine the optimal time to harvest Cabernet Sauvignon grapes under South African conditions. The following parameters were investigated during this study: seed lignification, maturity indexes, anthocyanin concentration per berry, sensory criteria (grape skins tasting and wine) and phenolic content. Berry development in four Cabernet Sauvignon vineyards in different South African winegrowing areas were investigated over the 2003, 2004 and 2005 seasons. The first parameter to be investigated was seed lignification percentages. Seasonal differences at commercial harvest were observed with values of 2004 varying between 73% and 91% compared to 59% and 80% for the 2003 and 2005 seasons but commercial harvest was two weeks later during the 2004 season. During this study it was found that seeds never reached 100% lignification for Cabernet Sauvignon as was found in previous work to indicate grape maturity. The development of anthocyanins also peaked well before the maximum seed lignification was reached. It therefore appears that seed lignification is not suitable for the determination of grape maturity for Cabernet Sauvignon grapes under South African conditions. The second parameter to be investigated was maturity indexes (Balling / Titratable Acidity (TA), Balling × pH, Balling × pH2). The best wine values were used to determine the optimal maturity index values. Morgenster was the only vineyard to consistently give values that corresponded to previously reported data (index values). Anhöhe and Plaisir de Merle reported higher maturity values than that reported in literature and seasonal variation was observed. Maturity index values for the best wines varied between 88 and 101 (Balling × pH) for Anhöhe during 2003 and 2005 seasons, but increased too between 97 and 107 (Balling × pH) for 2004. The maturity index values were found to be vineyard and season dependant, with warmer areas reaching higher values. From this study it appears that maturity index values as a singular maturity parameter does not give a good indication of berry maturity in all seasons or vineyards. Thirdly, the berry anthocyanin concentration (mg / berry and mg / g berry) were investigated and comparable trends were found between the four vineyards. However vineyards in warmer, drier regions (Anhöhe) tended to have higher anthocyanin concentrations per gram berry. The more vigorous vineyard of Morgenster consistently exhibited a higher anthocyanin concentration per berry. This can be explained by the ratio of skin to pulp between small berries (Anhöhe, 0.95 g - 2004) and larger berries South Africa is the eighth largest wine producing country in the world and face stiff competition on the world market. Cabernet Sauvignon is the most planted red cultivar in the world as well as in South Africa and can be seen as the wine by which countries are judged. The aim of this study was to investigate suitable, practical maturity parameters or combinations thereof to determine the optimal time to harvest Cabernet Sauvignon grapes under South African conditions. The following parameters were investigated during this study: seed lignification, maturity indexes, anthocyanin concentration per berry, sensory criteria (grape skins tasting and wine) and phenolic content. Berry development in four Cabernet Sauvignon vineyards in different South African winegrowing areas were investigated over the 2003, 2004 and 2005 seasons. The first parameter to be investigated was seed lignification percentages. Seasonal differences at commercial harvest were observed with values of 2004 varying between 73% and 91% compared to 59% and 80% for the 2003 and 2005 seasons but commercial harvest was two weeks later during the 2004 season. During this study it was found that seeds never reached 100% lignification for Cabernet Sauvignon as was found in previous work to indicate grape maturity. The development of anthocyanins also peaked well before the maximum seed lignification was reached. It therefore appears that seed lignification is not suitable for the determination of grape maturity for Cabernet Sauvignon grapes under South African conditions. The second parameter to be investigated was maturity indexes (Balling / Titratable Acidity (TA), Balling × pH, Balling × pH2). The best wine values were used to determine the optimal maturity index values. Morgenster was the only vineyard to consistently give values that corresponded to previously reported data (index values). Anhöhe and Plaisir de Merle reported higher maturity values than that reported in literature and seasonal variation was observed. Maturity index values for the best wines varied between 88 and 101 (Balling × pH) for Anhöhe during 2003 and 2005 seasons, but increased too between 97 and 107 (Balling × pH) for 2004. The maturity index values were found to be vineyard and season dependant, with warmer areas reaching higher values. From this study it appears that maturity index values as a singular maturity parameter does not give a good indication of berry maturity in all seasons or vineyards. Thirdly, the berry anthocyanin concentration (mg / berry and mg / g berry) were investigated and comparable trends were found between the four vineyards. However vineyards in warmer, drier regions (Anhöhe) tended to have higher anthocyanin concentrations per gram berry. The more vigorous vineyard of Morgenster consistently exhibited a higher anthocyanin concentration per berry. This can be explained by the ratio of skin to pulp between small berries (Anhöhe, 0.95 g - 2004) and larger berries (Morgenster, 1.82 g – 2004). Wine colour density (A420+A520) followed the same trend as the anthocyanin concentrations of the homogenate. Grape skins (G) were used to make an artificial wine that was evaluated by an expert panel to determine the development of the grapes. Wines (W) made from sampled batches were also evaluated by an expert panel for: colour intensity, vegetative, red berry, black berry with spice, acidity, astringency and general quality. Vegetative aromas and acidity decreased and red and black berry with spice increased during ripening for both berries and wine. Colour intensity also increased, corresponding to an increase in perceived general quality score. Correlations between general quality of both the grape skins tasting and wines were investigated. Balling showed a strong correlation with general quality of the grape skins tasting (r = 0.76; p = 0.00) but not as strongly with subsequent wines (r = 0.57; p = 0.00). Anthocyanin concentration (mg / g berry) of the berries (r = 0.36; p = 0.00), perceived colour intensity of grapes (r = 0.69; p = 0.00) and wine (r = 0.84; p = 0.00) correlated with general wine quality. The tasting panel identified wines that were statically better than the rest for each season and vineyard. Maximum berry anthocyanin concentration coincided with wines rated as the best by the tasting panel. More than one wine was identified during the maximum anthocyanin peak that did not differ statistically from the best wine. It appears from this study that a window period exists at the maximum anthocyanin peak, where wines of comparable quality, but different style, can be produced. Principal component analysis (PCA) was used to determine the least number of suitable parameters that could distinguish between unripe and ripe grapes in order to establish a grape maturity model. These differences were successfully described by Balling, TA, pH, potassium (K+), tartaric and malic acid. Anthocyanin concentration could further distinguish between ripe and overripe grapes in the model. From these parameters the minimum and maximum values were used to construct a universal ripeness model containing data from all four vineyards. Variation between the four vineyards caused too much overlapping in the universal model data as the vineyards were situated in different climatic regions according to the Winkler temperature model. On a per vineyard basis this did not occur to the same extend. The best rated Cabernet Sauvignon wines correlated strongly with soluble solid content; colour and quality perceptions of grapes, but large seasonal differences resulted in larger grape compositional variances than that of the individual vineyards in the different climatic zones. This illustrated the difficulty of pinpointing a specific parameter to indicate optimal ripeness. From this study it is clear that a universal maturity model for Cabernet Sauvignon berries is not attainable at present, but individual vineyard models shows the most potential. A preliminary study into the differences of the phenolic composition was done using reverse phase high performance liquid chromatography (RP-HPLC) on the homogenate and wine. Malvidin-3-glucoside and total anthocyanins followed comparable trends to that found for the Iland method. Strong correlations (r > 0.9) were found between the malvidin- 3-glucoside and malvidin-3-glucoside-acetate and p-coumarate; this was also true for the total anthocyanins in both homogenate and wine. Wines identified by a tasting panel to be the best quality, corresponded with the maximum anthocyanin concentration (mg / L) peak in the homogenate. Dense canopies at the Morgenster vineyard over the three seasons lead to lower total anthocyanin and quercetin-3-glucuronide concentrations compared to the Anhöhe and Plaisir de Merle vineyards. The shading of bunches by the dense canopy most likely contributed to this. Catechin, epicatechin, proanthocyanidin and polymeric phenol concentrations decreased significantly from veraison until harvest. Seasonal differences were noted in the four vineyards. No correlations could be found between the general wine quality and the phenolic compounds, but a weak trend was observed for total anthocyanins in the homogenate. A trend was found with the total flavan-3-ol to anthocyanin ratio determined by RP-HPLC analysis of the grape homogenates (r = 0.40, p = 0.00). This ratio varied between 1 and 3 for the wines rated as being the best quality. Phenols by themselves do not give a clear indication of optimal harvest time. From this study it appears that no single parameter could consistently indicate optimal ripeness over the seasons or per vineyard, but the maximum berry colour (anthocyanin concentration) did give an indication of optimal harvesting time. It is clear that a combination of parameters could predict the optimal time more precisely as with the above mentioned model but more research is needed to this end.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2011. / Includes bibliography. / ABSTRACT: The grapevine must constantly find a balance between two continually changing environments, the rhizosphere (i.e. soil) and the troposphere (i.e. macroclimate). The adaptations are extremely complex because they encompass complicated and interrelated processes that are not yet fully understood. In terms of water-use behaviour, differences between cultivars have been described in the literature. In this study, the water status and stomatal conductance of four cultivars (Shiraz, Grenache, Pinot noir and Chardonnay) grafted onto R99 were studied. Diurnal cycles of water status and stomatal conductance, from 07:00 to 19:00, were followed for a single day at the end of the 2009 season. The results showed that, at the end of the season, Shiraz was subjected to water stress conditions, losing leaves and showing symptoms of berry shrivelling. The other three cultivars had a much better canopy status and no symptoms of berry shrivelling were observed. Based on the canopy observations and a comparison of the curves of stem water potential (Ψs) and stomatal conductance (gs), it seems that Pinot noir and Chardonnay are closer to the water-use behaviour of Grenache noir, which is known as a “pessimistic” cultivar, than to Shiraz, which is an “optimistic” cultivar. A study of four plots each of Chardonnay/101.14 Mgt and Shiraz/101.14 Mgt was carried out in eight commercial vineyards in the Robertson region in order to investigate the relationship between soil and root morphology, and the influence thereof on canopy development and berry growth. These plots had different soil types. Important soil properties are reported to limit root growth, individually or as a combination of restrictions. It was found that the size of the root system of 101.14 Mgt is defined by soil physical and chemical properties. The roots of 101.14 Mgt under irrigation can grow to a depth of 100 cm or beyond if the soil physical and chemical properties allow it. Because the soil properties define the root system and the water storage/drainage, they greatly influence the plant water status, even under irrigation. In an arid zone like Robertson, irrigation is an important management tool. The balance between canopy growth before véraison and the ability of the root-soil system to maintain that canopy size during the ripening process is crucial in an area with a high evaporative demand. In this regard, not all the soil properties-root system combinations showed satisfactory performance in maintaining the canopy functioning, which affected berry sugar loading and berry volume. In another study that is presented, forty soil profiles were characterised in the Robertson valley. The root systems were considered as a product of the soil properties, and thus the morphology of the root systems was used as a starting point to group soils together. The importance of soil depth has been described well, thus the root systems were first classified according to rooting depth – into shallow and deep root systems. The deep root systems were then subdivided, creating two subgroups of high root density and low root density. The two extreme groups (i.e. shallow roots, and deep roots with high root density) have particularly different soil properties. The soil characteristics found in these extremes are represented up to certain point by families of the South African soil taxonomy, mainly due to the restrictive function of the B horizon. This restrictive function is related to soil properties that are taken into consideration in the South African soil classification and that are important for grapevine root growth, as well as the thickness of the described horizons and the physical and chemical differences between the horizons. Soil properties have an important influence on root morphology. Due to the fundamental role played by the root system in the overall plant functioning, soil properties are of critical importance. In an arid area, the low water pressure in the atmosphere and the high temperature greatly affect the plant water status. The soil-root system combination plays an important role in the ability of the root system to supply the plant with water during times of high evaporative demand. Different cultivars will react differently due to differences in transpiration control. The maintenance of an adequate water status will have an immense influence on canopy development and maintenance, and on normal and steady berry ripening. In this study it was found that not all the soil-root combinations can fulfil this satisfactorily. Thus, the grapevine balance determined by the combination of the soil-root-canopy complex and the influence of management techniques is extremely important for the favouring of a good canopy:root system ratio, a functional canopy throughout the season and a steady berry ripening curve.

Au Québec, la viticulture commerciale ou artisanale n’a que 35 ans. Cependant, le Québec est soumis à de nombreuses pressions climatiques comme la présence de gel hâtif à l’automne et tardif au printemps. La période de croissance (la différence entre le dernier gel au printemps et le premier gel à l’automne) est donc très limitée par la présence du froid. Dans un contexte de réchauffement climatique, cette période de croissance sera portée à s’allonger. Une plus longue période de croissance pourrait inciter les vignerons à modifier leurs cépages ou à augmenter la superficie cultivée. Trois vignobles ont fait l’objet d’étude et des prises de mesures spectrales des ceps y ont été effectuées. Des indices climatiques appliqués à la viticulture y ont été calculés sur une période de 30 ans avec les données du NARR et validés avec les données des stations météorologiques d’Environnement Canada. La moyenne de certains indices permet de les comparer à ceux des régions viticoles renommées comme Bordeaux et Dijon en France. L’étude des indices climatiques des 30 dernières années puis des 10 dernières années permet de découvrir qu’il existe un réel potentiel pour l’implantation de cépages nobles dans le sud du Québec. Ainsi, on remarque que l’énergie thermique est suffisante pour faire la culture de ces cépages. Cependant, la période sans gel est très variable et vient tempérer ces résultats. L’analyse des signatures spectrales de données de réalité de terrain permet de faire une différenciation entre les cépages en fonction des étapes de développement et de la vitesse d’adaptation des ceps aux pratiques culturales et au climat. Les longueurs d’onde entre 720-740 nm (proche infrarouge) et 550 nm (vert) sont les plus touchées par le changement. L’analyse dérivative permet d’éliminer les facteurs d’éclairement. De plus, il est possible de rehausser les différences dans les longueurs d’onde du pic de réflectance de la chlorophylle (≈720 nm). Avec toutes ses informations, il devient possible d’identifier les principaux cépages dans les vignobles grâce à des mesures spectrales temporelles. L’utilisation d’une image hyperspectrale et de données de réalité de terrain ont permis de différencier les cépages et d’en faire l’évolution phénologique entre deux saisons de croissance. Ainsi, avec l’extraction des signatures des pixels d’un secteur n’ayant pas subi de changement physiologique majeur (secteur de vieux ceps), la signature spectrale mesurée par le capteur est comparable à celles des données de réalité de terrain. L’analyse a permis de confirmer que l’énergie thermique acquise pour le 9 juillet 2009 (422 ∘C) est comparable à celle du 27 juin 2011 (419 ∘C). L’énergie thermique cumulée à ces deux dates suppose un développement comparable des cépages. Les similarités dans les signatures spectrales reflètent ce développement comparable.

In arid and semi-arid regions, water harvesting systems can augment water supply for crop production purposes. The functioning of this type of system is controlled by three major factors: weather, crop and soil characteristics. In particular, the weather factors vary stochastiscally and thus, need to be predicted on the basis of their probability of occurrence. Furthermore, long-term historical data is scarce in the arid regions. Consequently, the simulation approach is a good alternative for designing the system. This study developed a micro-computer based model, SSWHS89.BAS, for design of small scale water harvesting systems for perennial crops. The model uses elements of a simulation computer program, CLIMATE.BAS (Woolhiser, 1988), to generate daily rainfall, maximum and minimum temperature and radiation data and predicts evapotranspiration and runoff data from a deterministic computer program, PENMNSCS.BAS for the location of interest. The model was used to determine the characteristics of a water harvesting system in a vineyard field at Sonoita, Az.

Agricultural practices play a crucial role when discussing sustainable development in the world. Organic farming is a possibility to increase the overall sustainability, because it balances the environmental, economic, social and productive spheres better than conventional farming. Thus, Germany strives to have 20 % of the agricultural land organically certified. However, with current organic farmland at 6.2 %, the goal is far from being reached and conversion rates are slowing down, whereas organic viticulture indicates more successful conversion rates. Thus, the objective of this study is to investigate which motives and barriers wine farmers in Pfalz and Rheinhessen, Germany, have to convert to organic farming. Furthermore, it is explored which role one of the world’s biggest retailers, Systembolaget, plays in the decision process to produce organically or not. The study was carried out reviewing literature and through a questionnaire and interviews with, in both cases, eight farmers from the regions of which four were certified organic and four were conventional farmers. Moreover, the five capitals framework, which attempts to assess livelihood strategies, was applied to analyze findings. Results indicate that most motives for organic farming identified in the literature could be placed in the financial, social and human capital, whereas the questionnaire and interviews found as many categories in the natural capital. Barriers to convert to organic farming were most frequent in the natural and physical capital both in the literature and the empirics. However, the findings suggest that a focus lies on the financial and human capital, in which the economic situation and the ideology of a farmer played a crucial role in the decision process. Systembolaget plays a supporting role in the conversion to organic farming, but it is not the driving factor in a conversion process. The findings indicate that policy could consider revising financial support schemes, address ideological barriers against organic farming and decide on the use of copper. Moreover, the organic label as marketing tool could be stressed and the influence of the private sector could be acknowledged in order to reach the organic farmland goal of Germany.

Thesis (DPhil)--Stellenbosch University, 1970. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (PhD(Agric))--Stellenbosch University, 1970. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Climate is one of the most important factors influencing where wine grapes can be grown and the quality of wine produced from those grapes. A plants habitat has a profound influence on its growth and development. The surrounding climatic conditions at both the macro- and meso-scales influence the plant-climate miro-scale interactions. The main study site is the McKenzie Vineyard that is owned by Torlesse Wines. The climatic conditions of the surrounding Waipara region was also studied using climate data from the following vineyards; Canterbury House, River Terrace and Waipara West. The overall aim of this research is to improve understanding of the influence of the climatic environment on grapevine development at the meso- to micro-scale. The main findings of the research were firstly, that the most important climatic factor influencing grapevine development and growth is temperature and secondly that there is variability in the temperature across the Waipara Basin. Future research should be conducted for the entire growth season to gain a better understanding of how temperature influences the development of grapevine over the growing season as a whole.

Resumé The aim of the thesis is to provide a comprehensive overview of the current legislation of viticulture and winemaking in the Czech Republic, its historical evolution and it tries to approach the changes that shall be introduced by upcoming amendment of Act. No. 321/2004 Coll., on viticulture and winemaking and on changes of related laws. The work is divided to five chapters which are for clarity and better understanding of the issue divided to subchapters. The first part deals with the historical development of legislation of viticulture and winemaking in the context of evolution of the society and historical events that affected the development of viticulture and winemaking activities. The second part deals with the position of viticulture and winemaking law in the legal system of the Czech Republic and its connections with other branches of law. The third part provides complex overview of current Czech legislation of individual institutes of viticulture and winemaking law in relation to the provisions of the European law. The fourth part includes the overview of domestic and foreign organizations which activities are connected with aforementioned areas of crop production. The fifth and the last part of the thesis is aimed at provision of overview of changes to the Act on viticulture and winemaking...