Water Scarcity and Sustainable Agriculture in Semiarid Environment, 2018
Abstract Improved monitoring of water and heat fluxes in the vineyard can help to support more ef... more Abstract Improved monitoring of water and heat fluxes in the vineyard can help to support more efficient soil and crop management (e.g., irrigation). Row crops such as grapevines are more vulnerable to drought/heat stress due to increased exposition to radiative soil fluxes. Such soil effect can be particularly negative for canopy and cluster microclimates and conditions under Mediterranean dry and warm climate conditions. Our aim is to better understand diurnal and seasonal variation in water and heat fluxes in the vineyard and to assess how agronomic practices (e.g., irrigation, soil management) influence those fluxes in Mediterranean irrigated viticulture. We also address the use of thermography as a tool to assess vine's water status and visualize heat patterns/fluxes in a vineyard, to support canopy/soil management and feed models that can predict crop growth and irrigation needs.
Grapevine (Vitis vinifera L.) is one of the most economically important crops worldwide, especial... more Grapevine (Vitis vinifera L.) is one of the most economically important crops worldwide, especially due to the economic relevance of wine production. Abiotic stress, such as drought, may contribute to low yield, shifts in quality, and important economic loss. The predicted climate change phenomena point to warmer and dryer Mediterranean environmental conditions; as such, it is paramount to study the effects of abiotic stress on grapevine performance. Deficit irrigation systems are applied to optimize water use efficiency without compromising berry quality. In this research, the effect of two deficit irrigation strategies, sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI), in the grape berry were assessed. The effects of different levels of drought were monitored in Touriga Nacional at key stages of berry development (pea size, véraison, and full maturation) through RNA-Seq transcriptome analysis and by specific differentially expressed genes (DEGs) monitoring...
I Congresso Luso-Brasileiro de Horticultura. Sessão ViticulturaNos últimos anos tem-se verificado... more I Congresso Luso-Brasileiro de Horticultura. Sessão ViticulturaNos últimos anos tem-se verificado um aumento exponencial da utilização de robôs na agricultura, estando a União Europeia a fomentar fortemente a investigação nesta área através da Agenda de Investigação Estratégica para a Robótica na Europa. A grande importância do conhecimento da variabilidade espacial do vigor e produção em Viticultura, tem levado ao desenvolvimento de ferramentas de Viticultura de Precisão baseadas em sensores diversos montados em veículos autónomos. Neste trabalho apresentam-se alguns resultados de validação de campo obtidos no âmbito do projeto europeu VINBOT (“Autonomous cloud-computing vineyard robot to optimise yield management and wine quality”) que teve por objectivo o desenvolvimento de um robô terrestre, equipado com diversas câmaras e sensores, para obtenção de mapas de variabilidade espacial quer de características da sebe quer da produção de uma parcela de vinha. O ensaio de validação dec...
This paper aims to present some results of the EU VINBOT (Autonomous cloud-computing vineyard rob... more This paper aims to present some results of the EU VINBOT (Autonomous cloud-computing vineyard robot to optimize yield management and wine quality) project focused on vineyard yield estimation. A ground truth evaluation trial was set up in an experimental vineyard with two plots of the white varieties ‘Alvarinho’ and ‘Arinto’, trained on a vertical shoot positioning system and spur pruned. For each varietal plot, six smart points were selected with 10 contiguous vines each. During the ripening period of the 2016 season the vines were manually assessed for canopy dimensions and yield and then scanned by the VINBOT sensor head composed with a 2D laser rangefinder, a Kinect v2 camera and a set of robot navigation sensors. Ground truth data was used to compare with the canopy data estimated by the rangefinder and with the output of the image analysis algorithms. Regarding canopy features (height, volume and exposed leaf area), in general an acceptable fit between actual and estimated val...
Water is increasingly scarce in Mediterranean Europe and irrigated agriculture is one of the larg... more Water is increasingly scarce in Mediterranean Europe and irrigated agriculture is one of the largest and most inefficient users of this natural resource. Ecological topics such as the "water foot print" have become more relevant for the academy, consumers, governments and food industry. The wine sector needs solutions to improve its economical and environmental sustainability. Agronomical solutions, such as deficit irrigation (water supply below full crop evapotranspiration) have emerged as a tool for more efficient water use in irrigated viticulture and with likely positive effects on berry quality. Improving our understanding on the physiological and molecular basis of grapevine responses to water stress is an important task for research on irrigated viticulture. Better knowledge of the different genotypic responses (e.g., leaf gas exchange) to water stress can help to optimize crop/soil management and improve yield as well as berry quality traits under unfavourable climate conditions. Mild water deficits have direct and/or indirect (via the light environment in the cluster zone) effects on berry growth and composition. Another important challenge is to determine how soil water deficit regulate genes and proteins of the various metabolic pathways influencing berry composition and consequently wine quality. WATER SCARCITY, CLIMATE CHANGE AND WATER FOOT PRINT The majority of the grape acreage around the world is located in Mediterranean type climates, characterized by dry summers and mild winters (Table 1). Mediterranean Europe faces a situation of scarce water resources as a consequence of dry and hot summers, increasing consumption and mismanagement in both intensive agricultural and industrial activities (Carvalho, 2000; Tin, 2008; Collins et al., 2009). The climate change scenarios projected for the regions will exacerbate these impacts, with more frequent and extreme high temperature and drought events in many parts of Mediterranean Europe (IPPC, 2008). This may force a shift of production to cooler areas, the use of new cultivars/rootstocks better adapted to warmer and dryer conditions or changes in crop/soil management (Shultz and Stoll, 2010; Hunter et al., 2010; Lopes et al., 2011). Meanwhile consumers, retailers, politicians and the industry (agricultural included) have started to realise the need to use inputs like water in a more sustainable way (Chapagain and Orr, 2008; Cominelli et al., 2009; Clothier et al., 2010; Stefanelli et al., 2010). Therefore, concepts such as water and carbon footprint and their assessment are receiving increased attention. In basic terms, the footprint indicates the energy (carbon) or water used, related to both direct and indirect use by the consumer or producer. The water footprint is a consumption-based indicator of water use that looks at both direct and indirect water use of a consumer or producer (Hoekstra and Chapagain, 2008). It is calculated by the volume of fresh water used to produce the product, measured over the various steps of the production chain (Hoekstra, 2010). An increasing number of companies around the world recognise that reducing water foot print should be part of the corporate environmental strategy (Hoekstra, 2010; Clothier et al., 2010). A corporate water footprint strategy includes various aims and activities. Businesses can reduce their operational water footprint by decreasing water consumption in their own operations and by reducing water pollution to zero (Hoekstra et al.
Resumo Com o objectivo de estudar o efeito da rega e do regime hídrico no comportamento da casta ... more Resumo Com o objectivo de estudar o efeito da rega e do regime hídrico no comportamento da casta Touriga Nacional foi instalado um ensaio de rega numa vinha do Centro de Estudos Vitivinícolas do Dão, em Nelas. A transpiração da sebe de vinha foi estimada a partir dos registos de temperatura radiativa da sua superfície, recorrendo a um modelo bi-camada que tem por base o princípio da partição do balanço energético entre os componentes do coberto vegetal (videiras, solo e subcoberto herbáceo) admitindo que, do ponto de vista energético, a sebe e o substrato (solo+subcoberto) actuam separadamente e em paralelo. Os fluxos de calor latente da sebe de videiras são determinados a partir dos fluxos de calor sensível e do balanço de radiação. A evolução temporal de E c /ET o na modalidade de rega plena (FI) permite identificar três fases e corresponde à forma geral da curva de K cb indicada para a generalidade das culturas. A relação entre o coeficiente de secura (K s) e fracção de água utilizável do solo até 130 cm de profundidade (FTSW 130) é bifásica. Para valores de FTSW 130 superiores a 40-50%, o K s é aproximadamente constante, registando valores em torno de 1, correspondente a condições de conforto hídrico. Com valores de FTSW 130 inferiores, o K s tende a decrescer à medida que a reserva de água no solo diminui. Os menores valores de K s foram registados nos anos de 2005 (K s = 0,48) e 2006 (K s = 0,55), ambos na modalidade não regada (NI).
† Background A large proportion of vineyards are located in regions with seasonal drought (e.g. M... more † Background A large proportion of vineyards are located in regions with seasonal drought (e.g. Mediterraneantype climates) where soil and atmospheric water deficits, together with high temperatures, exert large constraints on yield and quality. The increasing demand for vineyard irrigation requires an improvement in the efficiency of water use. Deficit irrigation has emerged as a potential strategy to allow crops to withstand mild water stress with little or no decreases of yield, and potentially a positive impact on fruit quality. Understanding the physiological and molecular bases of grapevine responses to mild to moderate water deficits is fundamental to optimize deficit irrigation management and identify the most suitable varieties to those conditions. † Scope How the whole plant acclimatizes to water scarcity and how short-and long-distance chemical and hydraulic signals intervene are reviewed. Chemical compounds synthesized in drying roots are shown to act as long-distance signals inducing leaf stomatal closure and/or restricting leaf growth. This explains why some plants endure soil drying without significant changes in shoot water status. The control of plant water potential by stomatal aperture via feed-forward mechanisms is associated with 'isohydric' behaviour in contrast to 'anysohydric' behaviour in which lower plant water potentials are attained. This review discusses differences in this respect between grapevines varieties and experimental conditions. Mild water deficits also exert direct and/or indirect (via the light environment around grape clusters) effects on berry development and composition; a higher content of skin-based constituents (e.g. tannins and anthocyanins) has generally being reported. Regulation under water deficit of genes and proteins of the various metabolic pathways responsible for berry composition and therefore wine quality are reviewed.
The aim of this research was to test the effects of vineyard soil management practices combined w... more The aim of this research was to test the effects of vineyard soil management practices combined with deficit irrigation strategies on the performance of the grapevine (Vitisvinifera L.) red variety Tempranillo. Two soil management practices (soil tillage-ST and permanent resident vegetation-RV) were combined with three deficit irrigation treatments (regulated deficit irrigation-RDI, partial rootzone drying-PRD and conventional sustained deficit irrigation-DI) during two growing cycles. Compared to ST, RV reduced soil water content during spring, inducing a significant reduction in vine vegetative growth, yield and must titratable acidity. The effects of irrigation treatments were not much pronounced. Only in the second season RDI showed a significant reduction on vine vegetative growth, yield and must titratable acidity as compared to PRD and DI whose results were similar to one another. In a dry area such as ours and a low vigor vineyard, the combination of resident vegetation with deficit irrigation treatments should be carefully considered as it can reduce yield without any benefits to grape quality. In this site the conventional deficit irrigation should be preferred to RDI and PRD as it is technically the simplest deficit irrigation strategy and has enabled an efficient control of vegetative growth without negative impact on yield and berry composition as compared to the other irrigation treatments.
The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water u... more The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water use efficiency (A/g s) and carbon isotope composition (d 13 C) of two grapevine cultivars (Moscatel and Castelã o), growing in a commercial vineyard in SW Portugal. The study was done in two consecutive years (2001 and 2002). The treatments were full irrigation (FI), corresponding to 100% of crop evapotranspiration (ETc), rain-fed (no irrigation, NI), and two types of deficit irrigation (50% ETc): (i) by supplying the water either to one side of the root system or to the other, which is partial rootzone drying (PRD), or (ii) dividing the same amount of water by the two sides of the root system, the normal deficit irrigation (DI). The water supplied to the PRD treatment alternated sides approximately every 15 d. The values of predawn leaf water potential (W pd) and the cumulative integral of W pd (S W) during the season were lower in 2001 than in the 2002 growing season. Whereas differences in W pd and S W between PRD and DI were not significantly different in 2001, in 2002 (a dryer year) both cultivars showed lower values of S W in the PRD treatment as compared with the DI treatment. This suggests that partial rootzone drying may have a positive effect on water use under dryer conditions, either as a result of better stomatal control and/or reduced vigour. The effects of the water treatments on d 13 C were more pronounced in whole grape berries and pulp than in leaves. The d 13 C of pulp showed the best correlation with intrinsic water use efficiency (A/g s) as well as with S W. In spite of the better water status observed in PRD compared with DI in the two cultivars in 2002, no statistical differences between the two treatments were observed in A/g s and d 13 C. On the other hand, they showed a higher d 13 C compared with FI. In conclusion, it is apparent that the response to deficit irrigation varies with the environmental conditions of the particular year, the driest conditions exacerbating the differences among treatments. The highest values of d 13 C found in the pulp of NI vines in Castelã o compared with Moscatel suggest different sensitivities to water deficits in the two cultivars, as was empirically observed.
Grapevine irrigation is becoming an important practice to guarantee wine quality or even plant su... more Grapevine irrigation is becoming an important practice to guarantee wine quality or even plant survival in regions affected by seasonal drought. Nevertheless, irrigation has to be controlled to optimise source to sink balance and avoid excessive vigour. The results we present here in two grapevine varieties (Moscatel and Castelão) during 3 years, indicate that we can decrease the amount of water applied by 50% (as in deficit irrigation, DI, and in partial root drying, PRD) in relation to full crop’s evapotranspiration (ETc) [full irrigated (FI) vines] with no negative effects on production and even get some gains of quality (in the case of PRD). We report that in non‐irrigated and in several cases in PRD vines exhibit higher concentrations of berry skin anthocyanins and total phenols than those presented by DI and FI vines. We showed that these effects on quality were mediated by a reduction in vigour, leading to an increase on light interception in the cluster zone. Because plant w...
Improvements in water use efficiency of crops are essential under the scenarios of water scarcity... more Improvements in water use efficiency of crops are essential under the scenarios of water scarcity predicted by global change models for the Mediterranean region. In recent years, deficit irrigation, including partial root drying (PRD), has been proposed as an irrigation technique to improve water use efficiency and standardize grapevine yield and quality. The objective of this study was to evaluate the impact of deficit irrigation on photosynthetic responses of field grown grapevines of cv. Moscatel and Castelão. The treatments were: full irrigation (FI), corresponding to 100% ET c ; non-irrigated, but rain fed (NI) and partial root zone drying (PRD) and deficit irrigation (DI), both corresponding to an irrigation of 50% ET c. While in the DI treatment water was applied to both sides of the root system, in the PRD treatment, water was supplied to only one side of the root system, alternating sides periodically. In both cultivars, PRD and DI vines showed intermediate pre-dawn leaf water potential (c pd) values (around À0.4 MPa) while FI vines, showed c pd around À0.2 MPa during the growing season. NI showed the lowest c pd , reaching À0.6 MPa in Moscatel and À0.8 MPa in Castelão, at the end of growing season. Water status of PRD vines remained closer to FI than DI, especially at midday. Photosynthetic rates and fluorescence parameters of the deficit irrigation treatments (PRD and DI) did not show significant differences from FI vines, for most of the season. In Moscatel, although PRD generally showed g s , relative stomatal limitation (RSL) and intrinsic water use efficiency (A/g s) values closer to NI than DI, most of the differences between PRD and DI were not statistically significant. Our results showed a stability of the photosynthetic machinery in grapevines under low-to-moderate water availabilities, as demonstrated by the maintenance of the activity of three Calvin Cycle enzymes and of the V cmax values. However, a decline in J max was observed in NI vines, that can be a result either of a decrease in ATP production or, alternatively, of decreased mesophyll conductance to CO 2 diffusion. In general terms, stomatal limitation of photosynthesis is likely to be dominant in non-irrigated plants. Deficit irrigation had no negative impact on CO 2 assimilation, despite less water application than in full-irrigation. Differences among varieties may be related to differences in sensitivity of stomata, shoot growth and/or the interaction between rootstock and cultivar to soil water availability.
Accurate yield estimation is of utmost importance for the entire grape and wine production chain,... more Accurate yield estimation is of utmost importance for the entire grape and wine production chain, yet it remains an extremely challenging process due to high spatial and temporal variability in vineyards. Recent research has focused on using image analysis for vineyard yield estimation, with one of the major obstacles being the high degree of occlusion of bunches by leaves. This work uses canopy features obtained from 2D images (canopy porosity and visible bunch area) as proxies for estimating the proportion of occluded bunches by leaves to enable automatic yield estimation on non-disturbed canopies. Data was collected from three grapevine varieties, and images were captured from 1 m segments at two phenological stages (veraison and full maturation) in non-defoliated and partially defoliated vines. Visible bunches (bunch exposure; BE) varied between 16 and 64 %. This percentage was estimated using a multiple regression model that includes canopy porosity and visible bunch area as pr...
With the aim of analysing the infl uence of both the sub-region and weed-control practices on veg... more With the aim of analysing the infl uence of both the sub-region and weed-control practices on vegetation composition and dynamics in the Portuguese Dao Winegrowing Region, 120 vineyards were surveyed for weeds and winegrowers were asked to respond to a questionnaire in 2008. 206 taxa distributed across 31 families were recorded, with a predominance of Fabaceae, Asteraceae and Poaceae. The predominant vineyard inter-row soil management techniques were cover cropping (53%), with some cover sown but mostly relying on resident vegetation, and soil tillage (31%). Herbicides were applied in the row in 46%, and in the overall area in 4%, of the vineyards. Canonical correspondence analysis revealed signifi cant effects of the sub-region and the different soil management strategies on vineyard community structure. Compared with the last (and only) study, which took place in 1950, weed composition was different and species diversity increased. The present study showed that resident vegetation...
Nowadays it is recognized that vineyard yield estimation can bring several benefits to all the vi... more Nowadays it is recognized that vineyard yield estimation can bring several benefits to all the vine and wine industry and, consequently, there is a strong demand for fast and reliable yield estimation methods. Recently a strong effort has been made on developing machine vision tools to automatically estimate vineyard yields evolving several research teams worldwide. In this paper we aim to present preliminary results obtained in the frame of an European research project (VINBOT: "Autonomous cloud-computing vineyard robot to optimise yield management and wine quality") focus on yield estimation. A ground truth evaluation trial was set up in an experimental vineyard with the white variety Viosinho, trained on a vertical shoot positioning system and spur pruned. A sample of contiguous vines was labeled and submitted to a detailed assessment of vegetative and reproductive data to feed a viticulture data library. The vines were scanned during the ripening period of the 2015 season by the VINBOT sensor head composed with a set of sensors capable of capturing vineyard images and 3D data. Ground truth data was used to relate with images taken by the sensors and to test algorithms of image analysis. In this paper we present and discuss the relationships between actual and estimated yield computed using the surface occupied by the grape clusters in the images. Our preliminary results showed that, despite of a slight underestimation of the ground truth, caused mainly by cluster occlusion, when the canopy density allows visualization of most part of the clusters, the yield can be estimated by machine vision with a high fidelity. Further research is ongoing to test those devices and methodologies in other varieties and to improve the estimation accuracy.
Grapevines are highly dependent on arbuscular mycorrhizal fungi (AMF) for normal growth and devel... more Grapevines are highly dependent on arbuscular mycorrhizal fungi (AMF) for normal growth and development. However, vineyard soils may have low AMF abundance and diversity due to conventional soil management practices that are detrimental for these fungi. In this context, the establishment of AMF-inoculated cover crops can be a highly convenient strategy to reestablish soil mycorrhizal potential, as it combines the advantages of a vigorous inoculum source coming from mycorrhizal donor plants with the overall benefits of green covers for grape quality, microbial diversity and soil health. In this work, the potential benefits of Funneliformis mosseaeinoculated under-vine cover crops on grapevine growth, physiology and production were compared to those derived from 1) the establishment of non-inoculated under-vine cover crops, and 2) conventional herbicide-based weed control in the under-vine space. In addition, grapevine root AMF community composition was analyzed to assess if the introduction of a non-native AMF species induced changes on resident mycorrhizal community assemblies and to unveil potential variations in AMF diversity associated to herbicide replacement by green covers. Results indicated that under-vine cover crops, inoculated or not, led to a general vigor decrease in grapevines, probably due to competition between the two species. However, after a heat wave that occurred at harvest time in the second year of the experiment, grapevines growing in plots with inoculated cover crops had the highest photochemical reflectance indices and net photosynthesis rates, and partially compensated production losses due to berry sunburn. Root mycorrhizal community analysis by the end of the experiment revealed that the inoculated F. mosseae isolate colonized grapevine roots from inoculated plots, while it was absent in the other ones. Moreover, inoculation of this AMF did not lead to a replacement of native root AMF communities, but allowed further colonization by other resident Glomeraceae and non-Glomeraceae AMF taxa. Overall, the work herein demonstrates that the introduction of F. mosseae through donor plants is a suitable field inoculation method for grapevines and can help them to better withstand heat waves.
Aiming to assess the effects of irrigation amount on vegetative growth, yield and berry compositi... more Aiming to assess the effects of irrigation amount on vegetative growth, yield and berry composition of the red variety Touriga Nacional (Vitis vinifera L.) a fi eld trial was installed at the "Centro de Estudos Vitivinícolas do Dão", Nelas, Portugal. The effects of three irrigation treatments (DI30-30% of ETc; DI50-50% ETc and FI-100% ETc) were compared to a control non-irrigated (NI) during three growing seasons (2006-2008). Irrigation affected signifi cantly the fraction of available soil water and the pattern of soil water extraction by the roots either in the row and interrow. Predawn leaf water potential was also infl uenced by irrigation amount being the main differences observed between FI (highest values) and NI (lowest values). Compared to NI, the full irrigation treatment (FI) induced a signifi cantly higher vigour while the defi cit irrigation treatments (DI30 & DI50) returned intermediate values. The FI treatment induced a signifi cantly higher yield as compared to the other treatments which returned similar values. Compared to the control non-irrigated, the defi cit irrigation treatments presented similar berry composition during all the three seasons while the FI treatment showed a signifi cantly higher total acidity, lower total soluble solids and anthocyanins concentration. With the exception of the higher yield observed in FI treatment, in these three seasons irrigation had no other agronomical advantages enabling us to conclude that, in the ecological and viticultural conditions of the experiment, irrigation seems to be not necessary. However, further studies are needed mainly in soils with lower water holding capacity and in dryer years which frequency are expected to increase in the near future as a consequence of the climate change. RESUMO Com o objectivo de estudar a infl uência da rega no crescimento vegetativo, rendimento e composição da uva da casta Touriga Nacional (Vitis vinifera L.) foi instalado um ensaio numa vinha do Centro de Estudos Vitivinícolas do Dão, Nelas, Portugal. Compararam-se os efeitos de três modalidades de rega (DI30-30% ETc; DI50-50% ETc e FI-100% ETc) com uma testemunha não regada (NI) durante três anos consecutivos (2006 a 2008). A rega infl uenciou de forma signifi cativa quer a fracção de água disponível no solo quer o seu padrão de extracção na linha e entrelinha. O potencial hídrico foliar de base também foi infl uenciado pela rega tendo-se observado as maiores diferenças entre a modalidade FI (maiores valores) e a modalidade NI (menores valores). A modalidade FI apresentou um maior vigor quando comparada com a modalidade não regada enquanto as modalidades de rega defi citária (DI30 & DI50) apresentaram valores intermédios. Quando comparadas com a testemunha não regada, as modalidades de rega defi citária não apresentaram diferenças signifi cativas quer no rendimento quer na composição das uvas à vindima. A modalidade FI conduziu à obtenção de um maior rendimento e de mostos com acidez total mais elevada e teores em açúcar e antocianinas mais baixos que as restantes modalidades. Com excepção do maior rendimento obtido na modalidade FI, nestes três anos de ensaio a rega não proporcionou outras vantagens agronómicas pelo que podemos concluir que, nas condições ecológicas e vitícolas do ensaio, a rega parece ser uma técnica cultural desnecessária. No entanto são necessários mais estudos, sobretudo em solos com menor capacidade de retenção de água e em anos mais secos, cuja frequência se prevê que venha a aumentar no futuro próximo em consequência das alterações climáticas.
Water Scarcity and Sustainable Agriculture in Semiarid Environment, 2018
Abstract Improved monitoring of water and heat fluxes in the vineyard can help to support more ef... more Abstract Improved monitoring of water and heat fluxes in the vineyard can help to support more efficient soil and crop management (e.g., irrigation). Row crops such as grapevines are more vulnerable to drought/heat stress due to increased exposition to radiative soil fluxes. Such soil effect can be particularly negative for canopy and cluster microclimates and conditions under Mediterranean dry and warm climate conditions. Our aim is to better understand diurnal and seasonal variation in water and heat fluxes in the vineyard and to assess how agronomic practices (e.g., irrigation, soil management) influence those fluxes in Mediterranean irrigated viticulture. We also address the use of thermography as a tool to assess vine's water status and visualize heat patterns/fluxes in a vineyard, to support canopy/soil management and feed models that can predict crop growth and irrigation needs.
Grapevine (Vitis vinifera L.) is one of the most economically important crops worldwide, especial... more Grapevine (Vitis vinifera L.) is one of the most economically important crops worldwide, especially due to the economic relevance of wine production. Abiotic stress, such as drought, may contribute to low yield, shifts in quality, and important economic loss. The predicted climate change phenomena point to warmer and dryer Mediterranean environmental conditions; as such, it is paramount to study the effects of abiotic stress on grapevine performance. Deficit irrigation systems are applied to optimize water use efficiency without compromising berry quality. In this research, the effect of two deficit irrigation strategies, sustained deficit irrigation (SDI) and regulated deficit irrigation (RDI), in the grape berry were assessed. The effects of different levels of drought were monitored in Touriga Nacional at key stages of berry development (pea size, véraison, and full maturation) through RNA-Seq transcriptome analysis and by specific differentially expressed genes (DEGs) monitoring...
I Congresso Luso-Brasileiro de Horticultura. Sessão ViticulturaNos últimos anos tem-se verificado... more I Congresso Luso-Brasileiro de Horticultura. Sessão ViticulturaNos últimos anos tem-se verificado um aumento exponencial da utilização de robôs na agricultura, estando a União Europeia a fomentar fortemente a investigação nesta área através da Agenda de Investigação Estratégica para a Robótica na Europa. A grande importância do conhecimento da variabilidade espacial do vigor e produção em Viticultura, tem levado ao desenvolvimento de ferramentas de Viticultura de Precisão baseadas em sensores diversos montados em veículos autónomos. Neste trabalho apresentam-se alguns resultados de validação de campo obtidos no âmbito do projeto europeu VINBOT (“Autonomous cloud-computing vineyard robot to optimise yield management and wine quality”) que teve por objectivo o desenvolvimento de um robô terrestre, equipado com diversas câmaras e sensores, para obtenção de mapas de variabilidade espacial quer de características da sebe quer da produção de uma parcela de vinha. O ensaio de validação dec...
This paper aims to present some results of the EU VINBOT (Autonomous cloud-computing vineyard rob... more This paper aims to present some results of the EU VINBOT (Autonomous cloud-computing vineyard robot to optimize yield management and wine quality) project focused on vineyard yield estimation. A ground truth evaluation trial was set up in an experimental vineyard with two plots of the white varieties ‘Alvarinho’ and ‘Arinto’, trained on a vertical shoot positioning system and spur pruned. For each varietal plot, six smart points were selected with 10 contiguous vines each. During the ripening period of the 2016 season the vines were manually assessed for canopy dimensions and yield and then scanned by the VINBOT sensor head composed with a 2D laser rangefinder, a Kinect v2 camera and a set of robot navigation sensors. Ground truth data was used to compare with the canopy data estimated by the rangefinder and with the output of the image analysis algorithms. Regarding canopy features (height, volume and exposed leaf area), in general an acceptable fit between actual and estimated val...
Water is increasingly scarce in Mediterranean Europe and irrigated agriculture is one of the larg... more Water is increasingly scarce in Mediterranean Europe and irrigated agriculture is one of the largest and most inefficient users of this natural resource. Ecological topics such as the "water foot print" have become more relevant for the academy, consumers, governments and food industry. The wine sector needs solutions to improve its economical and environmental sustainability. Agronomical solutions, such as deficit irrigation (water supply below full crop evapotranspiration) have emerged as a tool for more efficient water use in irrigated viticulture and with likely positive effects on berry quality. Improving our understanding on the physiological and molecular basis of grapevine responses to water stress is an important task for research on irrigated viticulture. Better knowledge of the different genotypic responses (e.g., leaf gas exchange) to water stress can help to optimize crop/soil management and improve yield as well as berry quality traits under unfavourable climate conditions. Mild water deficits have direct and/or indirect (via the light environment in the cluster zone) effects on berry growth and composition. Another important challenge is to determine how soil water deficit regulate genes and proteins of the various metabolic pathways influencing berry composition and consequently wine quality. WATER SCARCITY, CLIMATE CHANGE AND WATER FOOT PRINT The majority of the grape acreage around the world is located in Mediterranean type climates, characterized by dry summers and mild winters (Table 1). Mediterranean Europe faces a situation of scarce water resources as a consequence of dry and hot summers, increasing consumption and mismanagement in both intensive agricultural and industrial activities (Carvalho, 2000; Tin, 2008; Collins et al., 2009). The climate change scenarios projected for the regions will exacerbate these impacts, with more frequent and extreme high temperature and drought events in many parts of Mediterranean Europe (IPPC, 2008). This may force a shift of production to cooler areas, the use of new cultivars/rootstocks better adapted to warmer and dryer conditions or changes in crop/soil management (Shultz and Stoll, 2010; Hunter et al., 2010; Lopes et al., 2011). Meanwhile consumers, retailers, politicians and the industry (agricultural included) have started to realise the need to use inputs like water in a more sustainable way (Chapagain and Orr, 2008; Cominelli et al., 2009; Clothier et al., 2010; Stefanelli et al., 2010). Therefore, concepts such as water and carbon footprint and their assessment are receiving increased attention. In basic terms, the footprint indicates the energy (carbon) or water used, related to both direct and indirect use by the consumer or producer. The water footprint is a consumption-based indicator of water use that looks at both direct and indirect water use of a consumer or producer (Hoekstra and Chapagain, 2008). It is calculated by the volume of fresh water used to produce the product, measured over the various steps of the production chain (Hoekstra, 2010). An increasing number of companies around the world recognise that reducing water foot print should be part of the corporate environmental strategy (Hoekstra, 2010; Clothier et al., 2010). A corporate water footprint strategy includes various aims and activities. Businesses can reduce their operational water footprint by decreasing water consumption in their own operations and by reducing water pollution to zero (Hoekstra et al.
Resumo Com o objectivo de estudar o efeito da rega e do regime hídrico no comportamento da casta ... more Resumo Com o objectivo de estudar o efeito da rega e do regime hídrico no comportamento da casta Touriga Nacional foi instalado um ensaio de rega numa vinha do Centro de Estudos Vitivinícolas do Dão, em Nelas. A transpiração da sebe de vinha foi estimada a partir dos registos de temperatura radiativa da sua superfície, recorrendo a um modelo bi-camada que tem por base o princípio da partição do balanço energético entre os componentes do coberto vegetal (videiras, solo e subcoberto herbáceo) admitindo que, do ponto de vista energético, a sebe e o substrato (solo+subcoberto) actuam separadamente e em paralelo. Os fluxos de calor latente da sebe de videiras são determinados a partir dos fluxos de calor sensível e do balanço de radiação. A evolução temporal de E c /ET o na modalidade de rega plena (FI) permite identificar três fases e corresponde à forma geral da curva de K cb indicada para a generalidade das culturas. A relação entre o coeficiente de secura (K s) e fracção de água utilizável do solo até 130 cm de profundidade (FTSW 130) é bifásica. Para valores de FTSW 130 superiores a 40-50%, o K s é aproximadamente constante, registando valores em torno de 1, correspondente a condições de conforto hídrico. Com valores de FTSW 130 inferiores, o K s tende a decrescer à medida que a reserva de água no solo diminui. Os menores valores de K s foram registados nos anos de 2005 (K s = 0,48) e 2006 (K s = 0,55), ambos na modalidade não regada (NI).
† Background A large proportion of vineyards are located in regions with seasonal drought (e.g. M... more † Background A large proportion of vineyards are located in regions with seasonal drought (e.g. Mediterraneantype climates) where soil and atmospheric water deficits, together with high temperatures, exert large constraints on yield and quality. The increasing demand for vineyard irrigation requires an improvement in the efficiency of water use. Deficit irrigation has emerged as a potential strategy to allow crops to withstand mild water stress with little or no decreases of yield, and potentially a positive impact on fruit quality. Understanding the physiological and molecular bases of grapevine responses to mild to moderate water deficits is fundamental to optimize deficit irrigation management and identify the most suitable varieties to those conditions. † Scope How the whole plant acclimatizes to water scarcity and how short-and long-distance chemical and hydraulic signals intervene are reviewed. Chemical compounds synthesized in drying roots are shown to act as long-distance signals inducing leaf stomatal closure and/or restricting leaf growth. This explains why some plants endure soil drying without significant changes in shoot water status. The control of plant water potential by stomatal aperture via feed-forward mechanisms is associated with 'isohydric' behaviour in contrast to 'anysohydric' behaviour in which lower plant water potentials are attained. This review discusses differences in this respect between grapevines varieties and experimental conditions. Mild water deficits also exert direct and/or indirect (via the light environment around grape clusters) effects on berry development and composition; a higher content of skin-based constituents (e.g. tannins and anthocyanins) has generally being reported. Regulation under water deficit of genes and proteins of the various metabolic pathways responsible for berry composition and therefore wine quality are reviewed.
The aim of this research was to test the effects of vineyard soil management practices combined w... more The aim of this research was to test the effects of vineyard soil management practices combined with deficit irrigation strategies on the performance of the grapevine (Vitisvinifera L.) red variety Tempranillo. Two soil management practices (soil tillage-ST and permanent resident vegetation-RV) were combined with three deficit irrigation treatments (regulated deficit irrigation-RDI, partial rootzone drying-PRD and conventional sustained deficit irrigation-DI) during two growing cycles. Compared to ST, RV reduced soil water content during spring, inducing a significant reduction in vine vegetative growth, yield and must titratable acidity. The effects of irrigation treatments were not much pronounced. Only in the second season RDI showed a significant reduction on vine vegetative growth, yield and must titratable acidity as compared to PRD and DI whose results were similar to one another. In a dry area such as ours and a low vigor vineyard, the combination of resident vegetation with deficit irrigation treatments should be carefully considered as it can reduce yield without any benefits to grape quality. In this site the conventional deficit irrigation should be preferred to RDI and PRD as it is technically the simplest deficit irrigation strategy and has enabled an efficient control of vegetative growth without negative impact on yield and berry composition as compared to the other irrigation treatments.
The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water u... more The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water use efficiency (A/g s) and carbon isotope composition (d 13 C) of two grapevine cultivars (Moscatel and Castelã o), growing in a commercial vineyard in SW Portugal. The study was done in two consecutive years (2001 and 2002). The treatments were full irrigation (FI), corresponding to 100% of crop evapotranspiration (ETc), rain-fed (no irrigation, NI), and two types of deficit irrigation (50% ETc): (i) by supplying the water either to one side of the root system or to the other, which is partial rootzone drying (PRD), or (ii) dividing the same amount of water by the two sides of the root system, the normal deficit irrigation (DI). The water supplied to the PRD treatment alternated sides approximately every 15 d. The values of predawn leaf water potential (W pd) and the cumulative integral of W pd (S W) during the season were lower in 2001 than in the 2002 growing season. Whereas differences in W pd and S W between PRD and DI were not significantly different in 2001, in 2002 (a dryer year) both cultivars showed lower values of S W in the PRD treatment as compared with the DI treatment. This suggests that partial rootzone drying may have a positive effect on water use under dryer conditions, either as a result of better stomatal control and/or reduced vigour. The effects of the water treatments on d 13 C were more pronounced in whole grape berries and pulp than in leaves. The d 13 C of pulp showed the best correlation with intrinsic water use efficiency (A/g s) as well as with S W. In spite of the better water status observed in PRD compared with DI in the two cultivars in 2002, no statistical differences between the two treatments were observed in A/g s and d 13 C. On the other hand, they showed a higher d 13 C compared with FI. In conclusion, it is apparent that the response to deficit irrigation varies with the environmental conditions of the particular year, the driest conditions exacerbating the differences among treatments. The highest values of d 13 C found in the pulp of NI vines in Castelã o compared with Moscatel suggest different sensitivities to water deficits in the two cultivars, as was empirically observed.
Grapevine irrigation is becoming an important practice to guarantee wine quality or even plant su... more Grapevine irrigation is becoming an important practice to guarantee wine quality or even plant survival in regions affected by seasonal drought. Nevertheless, irrigation has to be controlled to optimise source to sink balance and avoid excessive vigour. The results we present here in two grapevine varieties (Moscatel and Castelão) during 3 years, indicate that we can decrease the amount of water applied by 50% (as in deficit irrigation, DI, and in partial root drying, PRD) in relation to full crop’s evapotranspiration (ETc) [full irrigated (FI) vines] with no negative effects on production and even get some gains of quality (in the case of PRD). We report that in non‐irrigated and in several cases in PRD vines exhibit higher concentrations of berry skin anthocyanins and total phenols than those presented by DI and FI vines. We showed that these effects on quality were mediated by a reduction in vigour, leading to an increase on light interception in the cluster zone. Because plant w...
Improvements in water use efficiency of crops are essential under the scenarios of water scarcity... more Improvements in water use efficiency of crops are essential under the scenarios of water scarcity predicted by global change models for the Mediterranean region. In recent years, deficit irrigation, including partial root drying (PRD), has been proposed as an irrigation technique to improve water use efficiency and standardize grapevine yield and quality. The objective of this study was to evaluate the impact of deficit irrigation on photosynthetic responses of field grown grapevines of cv. Moscatel and Castelão. The treatments were: full irrigation (FI), corresponding to 100% ET c ; non-irrigated, but rain fed (NI) and partial root zone drying (PRD) and deficit irrigation (DI), both corresponding to an irrigation of 50% ET c. While in the DI treatment water was applied to both sides of the root system, in the PRD treatment, water was supplied to only one side of the root system, alternating sides periodically. In both cultivars, PRD and DI vines showed intermediate pre-dawn leaf water potential (c pd) values (around À0.4 MPa) while FI vines, showed c pd around À0.2 MPa during the growing season. NI showed the lowest c pd , reaching À0.6 MPa in Moscatel and À0.8 MPa in Castelão, at the end of growing season. Water status of PRD vines remained closer to FI than DI, especially at midday. Photosynthetic rates and fluorescence parameters of the deficit irrigation treatments (PRD and DI) did not show significant differences from FI vines, for most of the season. In Moscatel, although PRD generally showed g s , relative stomatal limitation (RSL) and intrinsic water use efficiency (A/g s) values closer to NI than DI, most of the differences between PRD and DI were not statistically significant. Our results showed a stability of the photosynthetic machinery in grapevines under low-to-moderate water availabilities, as demonstrated by the maintenance of the activity of three Calvin Cycle enzymes and of the V cmax values. However, a decline in J max was observed in NI vines, that can be a result either of a decrease in ATP production or, alternatively, of decreased mesophyll conductance to CO 2 diffusion. In general terms, stomatal limitation of photosynthesis is likely to be dominant in non-irrigated plants. Deficit irrigation had no negative impact on CO 2 assimilation, despite less water application than in full-irrigation. Differences among varieties may be related to differences in sensitivity of stomata, shoot growth and/or the interaction between rootstock and cultivar to soil water availability.
Accurate yield estimation is of utmost importance for the entire grape and wine production chain,... more Accurate yield estimation is of utmost importance for the entire grape and wine production chain, yet it remains an extremely challenging process due to high spatial and temporal variability in vineyards. Recent research has focused on using image analysis for vineyard yield estimation, with one of the major obstacles being the high degree of occlusion of bunches by leaves. This work uses canopy features obtained from 2D images (canopy porosity and visible bunch area) as proxies for estimating the proportion of occluded bunches by leaves to enable automatic yield estimation on non-disturbed canopies. Data was collected from three grapevine varieties, and images were captured from 1 m segments at two phenological stages (veraison and full maturation) in non-defoliated and partially defoliated vines. Visible bunches (bunch exposure; BE) varied between 16 and 64 %. This percentage was estimated using a multiple regression model that includes canopy porosity and visible bunch area as pr...
With the aim of analysing the infl uence of both the sub-region and weed-control practices on veg... more With the aim of analysing the infl uence of both the sub-region and weed-control practices on vegetation composition and dynamics in the Portuguese Dao Winegrowing Region, 120 vineyards were surveyed for weeds and winegrowers were asked to respond to a questionnaire in 2008. 206 taxa distributed across 31 families were recorded, with a predominance of Fabaceae, Asteraceae and Poaceae. The predominant vineyard inter-row soil management techniques were cover cropping (53%), with some cover sown but mostly relying on resident vegetation, and soil tillage (31%). Herbicides were applied in the row in 46%, and in the overall area in 4%, of the vineyards. Canonical correspondence analysis revealed signifi cant effects of the sub-region and the different soil management strategies on vineyard community structure. Compared with the last (and only) study, which took place in 1950, weed composition was different and species diversity increased. The present study showed that resident vegetation...
Nowadays it is recognized that vineyard yield estimation can bring several benefits to all the vi... more Nowadays it is recognized that vineyard yield estimation can bring several benefits to all the vine and wine industry and, consequently, there is a strong demand for fast and reliable yield estimation methods. Recently a strong effort has been made on developing machine vision tools to automatically estimate vineyard yields evolving several research teams worldwide. In this paper we aim to present preliminary results obtained in the frame of an European research project (VINBOT: "Autonomous cloud-computing vineyard robot to optimise yield management and wine quality") focus on yield estimation. A ground truth evaluation trial was set up in an experimental vineyard with the white variety Viosinho, trained on a vertical shoot positioning system and spur pruned. A sample of contiguous vines was labeled and submitted to a detailed assessment of vegetative and reproductive data to feed a viticulture data library. The vines were scanned during the ripening period of the 2015 season by the VINBOT sensor head composed with a set of sensors capable of capturing vineyard images and 3D data. Ground truth data was used to relate with images taken by the sensors and to test algorithms of image analysis. In this paper we present and discuss the relationships between actual and estimated yield computed using the surface occupied by the grape clusters in the images. Our preliminary results showed that, despite of a slight underestimation of the ground truth, caused mainly by cluster occlusion, when the canopy density allows visualization of most part of the clusters, the yield can be estimated by machine vision with a high fidelity. Further research is ongoing to test those devices and methodologies in other varieties and to improve the estimation accuracy.
Grapevines are highly dependent on arbuscular mycorrhizal fungi (AMF) for normal growth and devel... more Grapevines are highly dependent on arbuscular mycorrhizal fungi (AMF) for normal growth and development. However, vineyard soils may have low AMF abundance and diversity due to conventional soil management practices that are detrimental for these fungi. In this context, the establishment of AMF-inoculated cover crops can be a highly convenient strategy to reestablish soil mycorrhizal potential, as it combines the advantages of a vigorous inoculum source coming from mycorrhizal donor plants with the overall benefits of green covers for grape quality, microbial diversity and soil health. In this work, the potential benefits of Funneliformis mosseaeinoculated under-vine cover crops on grapevine growth, physiology and production were compared to those derived from 1) the establishment of non-inoculated under-vine cover crops, and 2) conventional herbicide-based weed control in the under-vine space. In addition, grapevine root AMF community composition was analyzed to assess if the introduction of a non-native AMF species induced changes on resident mycorrhizal community assemblies and to unveil potential variations in AMF diversity associated to herbicide replacement by green covers. Results indicated that under-vine cover crops, inoculated or not, led to a general vigor decrease in grapevines, probably due to competition between the two species. However, after a heat wave that occurred at harvest time in the second year of the experiment, grapevines growing in plots with inoculated cover crops had the highest photochemical reflectance indices and net photosynthesis rates, and partially compensated production losses due to berry sunburn. Root mycorrhizal community analysis by the end of the experiment revealed that the inoculated F. mosseae isolate colonized grapevine roots from inoculated plots, while it was absent in the other ones. Moreover, inoculation of this AMF did not lead to a replacement of native root AMF communities, but allowed further colonization by other resident Glomeraceae and non-Glomeraceae AMF taxa. Overall, the work herein demonstrates that the introduction of F. mosseae through donor plants is a suitable field inoculation method for grapevines and can help them to better withstand heat waves.
Aiming to assess the effects of irrigation amount on vegetative growth, yield and berry compositi... more Aiming to assess the effects of irrigation amount on vegetative growth, yield and berry composition of the red variety Touriga Nacional (Vitis vinifera L.) a fi eld trial was installed at the "Centro de Estudos Vitivinícolas do Dão", Nelas, Portugal. The effects of three irrigation treatments (DI30-30% of ETc; DI50-50% ETc and FI-100% ETc) were compared to a control non-irrigated (NI) during three growing seasons (2006-2008). Irrigation affected signifi cantly the fraction of available soil water and the pattern of soil water extraction by the roots either in the row and interrow. Predawn leaf water potential was also infl uenced by irrigation amount being the main differences observed between FI (highest values) and NI (lowest values). Compared to NI, the full irrigation treatment (FI) induced a signifi cantly higher vigour while the defi cit irrigation treatments (DI30 & DI50) returned intermediate values. The FI treatment induced a signifi cantly higher yield as compared to the other treatments which returned similar values. Compared to the control non-irrigated, the defi cit irrigation treatments presented similar berry composition during all the three seasons while the FI treatment showed a signifi cantly higher total acidity, lower total soluble solids and anthocyanins concentration. With the exception of the higher yield observed in FI treatment, in these three seasons irrigation had no other agronomical advantages enabling us to conclude that, in the ecological and viticultural conditions of the experiment, irrigation seems to be not necessary. However, further studies are needed mainly in soils with lower water holding capacity and in dryer years which frequency are expected to increase in the near future as a consequence of the climate change. RESUMO Com o objectivo de estudar a infl uência da rega no crescimento vegetativo, rendimento e composição da uva da casta Touriga Nacional (Vitis vinifera L.) foi instalado um ensaio numa vinha do Centro de Estudos Vitivinícolas do Dão, Nelas, Portugal. Compararam-se os efeitos de três modalidades de rega (DI30-30% ETc; DI50-50% ETc e FI-100% ETc) com uma testemunha não regada (NI) durante três anos consecutivos (2006 a 2008). A rega infl uenciou de forma signifi cativa quer a fracção de água disponível no solo quer o seu padrão de extracção na linha e entrelinha. O potencial hídrico foliar de base também foi infl uenciado pela rega tendo-se observado as maiores diferenças entre a modalidade FI (maiores valores) e a modalidade NI (menores valores). A modalidade FI apresentou um maior vigor quando comparada com a modalidade não regada enquanto as modalidades de rega defi citária (DI30 & DI50) apresentaram valores intermédios. Quando comparadas com a testemunha não regada, as modalidades de rega defi citária não apresentaram diferenças signifi cativas quer no rendimento quer na composição das uvas à vindima. A modalidade FI conduziu à obtenção de um maior rendimento e de mostos com acidez total mais elevada e teores em açúcar e antocianinas mais baixos que as restantes modalidades. Com excepção do maior rendimento obtido na modalidade FI, nestes três anos de ensaio a rega não proporcionou outras vantagens agronómicas pelo que podemos concluir que, nas condições ecológicas e vitícolas do ensaio, a rega parece ser uma técnica cultural desnecessária. No entanto são necessários mais estudos, sobretudo em solos com menor capacidade de retenção de água e em anos mais secos, cuja frequência se prevê que venha a aumentar no futuro próximo em consequência das alterações climáticas.
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