Can Mediterranean terroirs withstand climate change ? Case studies at the Alentejo portuguese winegrowing region

XII Congreso Internacional TerroirClimate change introduced new challenges to vinegrowers in the Mediterranean areas such as the hot and dry winegrowing region of Alentejo, south Portugal. Warmer and drier conditions are harmful for grape yield and berry quality attributes and for vine’s longevity, mainly when optimal thresholds are exceeded. Therefore winegrowers are forced to move from rainfed to irrigated production systems making Alentejo’ wine production strongly based on available water resources for irrigation. This work aims to review and discuss ecophysiological and agronomical data obtained in irrigation trials set up at different terroirs of Alentejo. In the last four decades, classical bioclimatic temperature-based indices showed a significantly positive trend, while the dryness index present a negative trend over time. Furthermore, ecophysiological data collected in deficit irrigation experiments are reviewed and discussed, focusing on the effects of drought and heat stress on vigour, yield and berry composition. Emphasis is given on the indirect effects of leaf senescence on cluster exposure and consequences on berry temperature and composition. In order to promote the sustainability and quality of wine production in these hot and dry terroirs short- to longterm adaptation measures are suggested. The limitations and risks of using deficit irrigation during heat waves are also underlinedinfo:eu-repo/semantics/publishedVersio

Chickpea genotype adaptation to Mediterranean Environment

Genotypes that fasten their development cycle showed higher grain yield. Earlier start of flowering means higher soil water availability and lower maximum temperatures (middle of April), allowing to set more flowers and pods per plant and consequently higher grain yield. End of flowering started on May 19 in earlier genotypes. On this date the most hydrated genotypes are the ones with the longest growth cycle. On May 19 the genotypes with higher grain yield were at the end of flowering and showed lower predawn water potential. Grain yield showed a good correlation with all yield components except with the 100 Seeds Weight (100SW). End of flowering started on May 19 in earlier genotypes. On this date the most hydrated genotypes are the ones with the longest growth cycle. On May 19 the genotypes with higher grain yield were at the end of flowering and showed lower predawn water potential. Grain yield showed a good correlation with all yield components except with the 100 Seeds Weight (100SW)

Physiological responses of grapevine leaves to Bordeaux mixture under light stress conditions

The effect of Bordeaux mixture on the physiology of leaves of Vitis vinifera L., cv. Touriga Nacional, growing under field conditions in the Douro Wine Region, was evaluated. Especially in late summer, this fungicide modifies the light microclimate and leaf physiological characteristics, namely stomatal aperture and photosynthesis. Leaves treated with Bordeaux mixture showed higher reflectance, whereas transmitted photon flux density and temperature were lower compared to control leaves. Photosynthetic rates of treated leaves increased due to a lowering of both, stomatal and non-stomatal limitation. In addition, transpiration rates were higher, but neither the intrinsic efficiency of water use nor leaf water potentials were affected. Delay of leaf senescence of grapevines sprayed with Bordeaux mixture inhibited scorching of clusters and, consequently, led to higher yields per plant.

Screening chickpea resistance to water deficits: the yield perspective.

Screening a wide range of germplasm from our major crops (including legumes) to search for genetic variation of traits involved in stress resistance is extremely relevant in the context of predicted increase in aridity in several areas of the world, including the Mediterranean (1,2). On the other hand, the keystone of ‘crop drought resistance’ relies on the effective use by the crop of a limiting water supply (3,4). This can be achieved by choosing the appropriate genotype and/or agronomical practices such as the adjustment of crop phenology to its environment or the use of deficit irrigation. In the framework of the EU project KBBE-2008-212337 ‘Sustainable water use securing food production in dry areas of the Mediterranean region (SWUP-MED)’ we are studying a wide range of chickpea (Cicer arietinum L.) accessions in two sites (South Portugal and Syria/ICARDA) in what concerns yield potential under limiting and non-limiting soil water and the physiological traits underlying those responses. Chickpea is a widely grown grain legume offering high-quality protein, besides providing an input of N2 into the soil and a disease break in rotation with other crops. However, yield is still low in many of the growing regions, especially when terminal drought is likely to occur (5). We have identified a significant genetic variability in what concerns yield (from 1000 to above 2000kg. ha-1 under rainfed conditions), harvest index (from 25 to 60%) and plant water status under similar available soil water. Phenological differences may play an important role in explaining yield differences in the accessions studied. In addition to yield we will study seed quality traits as affected by the genotype and the environment. Our results will be used to model crop water requirements, predict yields and support breeding efforts (6)

Co2 efflux, co2 concentration and photosynthetic refixation in stems of Eucalyptus globulus (Labill.)

Research PaperIn spite of the importance of respiration in forest carbon budgets, the mechanisms by which physiological factors control stem respiration are unclear. An experiment was set up in a Eucalyptus globulus plantation in central Portugal with monoculture stands of 5-year-old and 10-year-old trees. CO2 efflux from stems under shaded and unshaded conditions, as well as the concentration of CO2 dissolved in sap [CO2 *], stem temperature, and sap flow were measured with the objective of improving our understanding of the factors controlling CO2 release from stems of E. globulus. CO2 efflux was consistently higher in 5-year-old, compared with 10-year-old, stems, averaging 3.4 versus 1.3 mmol m22 s21, respectively. Temperature and [CO2 *] both had important, and similar, influences on the rate of CO2 efflux from the stems, but neither explained the difference in the magnitude of CO2 efflux between trees of different age and size. No relationship was found between efflux and sap flow, and efflux was independent of tree volume, suggesting the presence of substantial barriers to the diffusion of CO2 from the xylem to the atmosphere in this species. The rate of corticular photosynthesis was the same in trees of both ages and only reduced CO2 efflux by 7%, probably due to the low irradiance at the stem surface below the canopy. The younger trees were growing at a much faster rate than the older trees. The difference between CO2 efflux from the younger and older stems appears to have resulted from a difference in growth respiration rather than a difference in the rate of diffusion of xylemtransported CO

Regulation of cell death induced by acetic acid in yeasts

Acetic acid has long been considered a molecule of great interest in the yeast research field. It is mostly recognized as a by-product of alcoholic fermentation or as a product of the metabolism of acetic and lactic acid bacteria, as well as of lignocellulosic biomass pretreatment. High acetic acid levels are commonly associated with arrested fermentations or with utilization as vinegar in the food industry. Due to its obvious interest to industrial processes, research on the mechanisms underlying the impact of acetic acid in yeast cells has been increasing. In the past twenty years, a plethora of studies have addressed the intricate cascade of molecular events involved in cell death induced by acetic acid, which is now considered a model in the yeast regulated cell death field. As such, understanding how acetic acid modulates cellular functions brought about important knowledge on modulable targets not only in biotechnology but also in biomedicine. Here, we performed a comprehensive literature review to compile information from published studies performed with lethal concentrations of acetic acid, which shed light on regulated cell death mechanisms. We present an historical retrospective of research on this topic, first providing an overview of the cell death process induced by acetic acid, including functional and structural alterations, followed by an in-depth description of its pharmacological and genetic regulation. As the mechanistic understanding of regulated cell death is crucial both to design improved biomedical strategies and to develop more robust and resilient yeast strains for industrial applications, acetic acid-induced cell death remains a fruitful and open field of study. © 2021 Chaves, Rego, Martins, Santos-Pereira, Sousa and Côrte-Real.This work was supported by the "Contrato-Programa" UIDB/04050/2020 funded by national funds through the FCT I.P.info:eu-repo/semantics/publishedVersio

Limitations to leaf photosynthesis in field-grown grapevine under drought - metabolic and modelling approaches

The effects of a slowly-imposed drought stress on gas-exchange, chlorophyll a fluorescence, biochemical and physiological parameters of Vitis vinifera L. leaves (cv. Aragonez, syn. Tempranillo) growing in a commercial vineyard (South Portugal) were evaluated. Relative to well-watered plants (predawn water potential, ΨPD = –0.13 ± 0.01 MPa), drought-stressed plants (ΨPD = –0.97 ± 0.01 MPa) had lower photosynthetic rates (ca 70%), stomatal conductance, and PSII activity (associated with a higher reduction of the quinone A pool and lower efficiency of PSII open centres). Stomatal limitation to photosynthesis was increased in drought-stressed plants relative to well-watered plants by ca 44%. Modelled responses of net photosynthesis to internal CO2 indicated that drought-stressed plants had significant reductions in maximum Rubisco carboxylation activity (ca 32%), ribulose-1,5-bisphosphate regeneration (ca 27%), and triose phosphate (triose-P) utilization rates (ca 37%) relative to well-watered plants. There was good agreement between the effects of drought on modelled biochemical parameters, and in vitro activities of key enzymes of carbon metabolism, namely Rubisco, glyceraldehyde-3-phosphate dehydrogenase, ribulose-5-phosphate kinase and fructose-1,6-bisphosphate phosphatase. Quantum yields measured under both ambient (35 Pa) and saturating CO2 (100 Pa) for drought-stressed plants were decreased relative to well-watered plants, as well as maximum photosynthetic rates measured at light and CO2 saturating conditions (three times ambient CO2 levels). Although stomatal closure was a strong limitation to CO2 assimilation under drought, comparable reductions in electron transport, CO2 carboxylation, and utilization of triose-P capacities were also adaptations of the photosynthetic machinery to dehydration that slowly developed under field conditions. Results presented in this study confirm that modelling photosynthetic responses based on gas-exchange data can be successfully used to predict metabolic limitations to photosynthesis

Impact of deficit irrigation on water use efficiency and carbon isotope composition (δ13C) of field-grown grapevines under Mediterranean climate

The objective of this study was to evaluate the effect of deficit irrigation on intrinsic water use efficiency (A/gs) and carbon isotope composition (δ 13C) of two grapevine cultivars (Moscatel and Castelão), 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 (ψpd) and the cumulative integral of ψpd (Sψ) during the season were lower in 2001 than in the 2002 growing season. Whereas differences in Wpd and SW between PRD and DI were not significantly different in 2001, in 2002 (a dryer year) both cultivars showed lower values of SW 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 δ13C were more pronounced in whole grape berries and pulp than in leaves. The δ13C of pulp showed the best correlation with intrinsic water use efficiency (A/gs) as well as with Sψ. 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/gs and δ13C. On the other hand, they showed a higher δ13C 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 d13C found in the pulp of NI vines in Castela˜o compared with Moscatel suggest different sensitivities to water deficits in the two cultivars, as was empirically observed

Grape berry metabolism in field-grown grapevines exposed to different irrigation strategies

The response of grape berry metabolism to vine water status was investigated in field grown grapevines (Vitis vinifera cv. Castelão) in southern Portugal. Water was supplied as: full irrigation (FI), to minimum water deficit corresponding to 100 % of crop evapotranspiration (Etc), partial rootzone drying (PRD) and deficit irrigation (DI), both corresponding to an irrigation amount of 50 % Etc, and a rainfed, i.e. no irrigation treatment (NI). In PRD, water was supplied to one side of the root system during each irrigation period, alternating sides every 15 d approximately. During the growing period, PRD and DI vines showed intermediate pre-dawn leaf water potential (Ψpd) values (around -0.4 MPa) by the end of the growing season, FI vines -0.2 MPa and NI -0.8 MPa. Berry weight as well as the content of glucose and fructose per berry increased in irrigated vines (PRD, DI, and FI) compared to NI vines. Although both malic and tartaric acid declined in non-irrigated vines, there was no significant difference between treatments at harvest. The activities of invertase, malate dehydrogenase and malic enzyme were not affected by irrigation throughout the ripening process. The contribution of other factors involved in the reduction of sugars and organic acids in berries of non-irrigated vines are discussed. These results show that deficit irrigation, like PRD and DI, do not have any negative impact on growth and quality of grape berries compared to fully irrigated vines, but may result in improved berry quality compared to rainfed vines

Deficit irrigation in grapevine improves water-use efficiency while controlling vigour and production quality

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 Castela ˜o) during 3 years, indicate thatwe can decrease the amount ofwater 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 weremediated by a reduction in vigour, leading to an increase on light interception in the cluster zone. Because plant water status during most of the dates along the season was not significantly different between PRD and DI, and when different, PRD even exhibited a higher leaf water potential than DI vines, we conclude that growth inhibition in PRD was not a result of a hydraulic control. The gain in crop water use in DI and PRD was accompanied by an increase of the δ13 C values in the berries in DI and PRD as compared to FI, suggesting that we can use this methodology to assess the integrated water-use efficiency over the growing season