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The exposure of viticulture to climate change and extreme weather conditions makes the winemaking sector particularly vulnerable, being one of its major challenges in the current century. While grapevine is considered a highly tolerant crop to several abiotic stresses, Mediterranean areas are frequently affected by adverse environmental factors, namely water scarcity, heat and high irradiance, and are especially vulnerable to climate change. Due to the high socio-economic value of this sector in Europe, the study of adaptation strategies to mitigate the negative climate change impacts are of main importance for its sustainability and competitiveness. Adaptation strategies include all the set of actions and processes that can be performed in response to climate change. It is crucial to improve agronomic strategies to offset the loss of productivity and likely changes in production and fruit quality. It is important to look for new insights concerning response mechanisms to these stresses to advance with more effective and precise measures. These measures should be adjusted to local terroirs and regional climate change projections for the sustainable development of the winemaking sector. This review describes the direct climate change impacts (on phenology, physiology, yield and berry quality), risks, and uncertainties for Mediterranean viticulture, as well as a set of canopy, soil and water management practices that winegrowers can use to adapt their vines to warmer and drier conditions.

Field-grown grapevines are often exposed to multiple environmental stresses, which challenges wine-growers to develop sustainable measures to sustain vine growth, yield, and quality. Under field conditions this task is demanding, due to differences in the magnitudes of stresses and associated plant responses. In this study we explored the hypothesis that kaolin-particle film application improves grapevine photoprotection through the regulation of xanthophyll cycle genes, limiting the thermal dissipation of excess energy under harsh environmental conditions. Hence, we selected two grapevine varieties, Touriga-Nacional (TN) and Touriga-Franca (TF), grown in the Douro Demarcated Region, and evaluated changes in light dissipation mechanisms, xanthophyll cycle components, and the expression of xanthophyll cycle genes during the 2017 summer season. The results showed that, from veraison to ripening, kaolin triggered the up-regulation of violaxanthin de-epoxidase (VvVDE1) and zeaxanthin epoxidase (VvZEP1) genes, indicating optimised regulation of the xanthophyll cycle. Kaolin treatment also decreased chlorophyll (Chla, Chlb, Chl(a+b)) and carotenoid (Car) accumulation under increasing summer stress conditions in both varieties and lowered the non-photochemical quenching (NPQ) of grapevines on ripening, suggesting a long-term response to summer stress. In addition, kaolin-treated grapevines showed increased Chla/Chlb and lower Chl(a+b)/Car ratios, displaying some features of high light adapted leaves. Overall, this study suggests that kaolin application enabled grapevines to benefit from fluctuating periods of summer stress by managing chlorophyll and carotenoid content and limiting down-regulation of both photochemistry and photoinhibition processes. Under Mediterranean field conditions, kaolin application can be considered an efficient method of minimising summer stress impact on grapevines., This work was supported by National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020, the Clim4Vitis project – “Climate change impact mitigation for European viticulture: knowledge transfer for an integrated approach”, funded by the European Union's Horizon 2020 Research and Innovation programme, under grant agreement no. 810176, and by the project I&D&I AgriFood XXI, operation NORTE-01-0145-FEDER-000041, co-funded by the European Regional Development Fund (FEDER) through NORTE 2020 (Programa Operacional Regional do Norte, 2014/2020). Sara Bernardo acknowledges the financial support provided by the FCT-Portuguese Foundation for Science and Technology (PD/BD/128273/2017) under the Doctoral Programme “Agricultural Production Chains – from Fork to Farm”.

Kaolin-particle film has been considered a low-cost technology to mitigate the adverse effects of high light and temperature, and drought in several crops. However, the underlying excess energy absorption and dissipation mechanisms, and related components associated with kaolin photoprotective effects in grapevines are poorly explored. This study aims to understand the interactions between kaolin foliar treatment and photosynthetic pigments accumulation, carotenoids metabolism, xanthophyll cycle regulation, and its putative role on the non-photochemical quenching (NPQ) processes in Touriga-Franca (TF) and Touriga-Nacional (TN) varieties. The experiments were conducted during the 2017 summer season in a commercial vineyard, and measurements were performed at pre-dawn and midday in each sampling date (EL35 – veraison; EL38 – full mature). Overall, TF variety showed higher accumulation of chlorophylls, xanthophylls, and de-epoxidation state (DPS) than TN. Kaolin treatment enhanced TN chlorophyll accumulation up to 114 % at EL35 (veraison) and 123 % at EL38 (full mature), highlighting its protective role on chlorophyll degradation, while no changes were found in TF, which might indicate a lower need for particle-film technology in this variety under the current environmental conditions. Individual carotenoids were mainly higher in the treated leaves of both varieties, as well as the xanthophyll cycle pigments zeaxanthin (Zx) and violaxanthin (Vx). Simultaneously, the DPS and NPQ values were lower in TN and TF treated leaves (1.92 – 2.36) compared to untreated vines (3.19 – 3.24), suggesting that there might be other components influencing NPQ levels beyond Zx, with an indirect role in long-lasting NPQ processes. In addition, in the TF kaolin-treated leaves, violaxanthin de-epoxidase (VvVDE1) and zeaxanthin epoxidase (VvZEP1) gene expression were respectively 3-fold and 4-fold upregulated at stage EL35, while VvZEP1 gene expression decreased at stage EL38 in TN kaolin-treated leaves, indicating an optimised regulation of the xanthophyll cycle. These findings suggest that kaolin treatment promoted a fine-tuning of grapevine summer stress responses under sustained summer stress factors, by managing xanthophyll cycle dynamics, and pigments accumulation., This work was supported by National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020, the Clim4Vitis project – "Climate change impact mitigation for European viticulture: knowledge transfer for an integrated approach", funded by European Union's Horizon 2020 research and innovation programme, under grant agreement no. 810176. Authors acknowledge Rui Flores from “Herdade do Esporão”, for the collaboration and efforts in making the vineyard facilities available for this study, as well as BASF collaboration, namely Paulo Matos. The technical assistance of Inmaculada Carbonell (IATA-CSIC) in pigment analysis is also gratefully acknowledged. Sara Bernardo acknowledges the financial support provided by the FCT-Portuguese Foundation for Science and Technology (PD/BD/ 128273/2017), under the Doctoral Programme "Agricultural Production Chains – from fork to farm", and Dinis L.-T. thanks the FCT and UTAD for the research contract (D.L. Law no. 57/2017).

Different SA concentrations (10, 100 and 1000 μM) were applied in young olive trees (Olea europaea L.) subjected to drought and rewatering. Plants treated with 10 μM exhibited a close behavior to SA-starved plants. Although both 100 and 1000 μM improved the balance between ROS production and scavenging, 100 μM was more efficient. During drought, 100 μM improved ROS detoxification and scavenging by the maintenance or overaccumulation of soluble proteins. During recovery, soluble proteins return to well-watered values and increased the investment in non-enzymatic antioxidants. 100 μM was also the most effective in plant ionome regulation, improving macro and micronutrients uptake, namely P, Fe, Mn and Zn, and changing mineral allocation patterns. Therefore, 100 μM also countered the drought-induced decline in total plant biomass accumulation. The application of suitable SA concentrations is an efficient tool to improve cellular homeostasis and growth of plants subjected to recurrent drought episodes.

In the context of climate change, the combination of the drought, salinity, heat and high irradiance felt in many regions around the world will be intensified, further worsening the adverse effects on plant growth and development at different scales. This scenario will have severe repercussions on agricultural crops, compromising yields and harvest qualities. Kaolin (KL) clay has been recognized as a promising short-term strategy for the sustainable alleviation of adverse abiotic stress. However, some mechanisms that support KL-induced stress alleviation remain minimally discussed, and there is still no consensus on its effectiveness in different crops and under different stress prevalences and/or intensities. Based on most available reports, this review illustrates KL’s modes of action and critically appraises crop responses to KL application, namely, its influence on temperature, irradiation reflection, leaf structure, water status, photosynthetic capacity, biochemical responses, mineral composition, growth, yield and quality. Finally, this review briefly highlights some less explored aspects that merit attention.

Research ArticleReceived: 22 December 2020 Revised: 6 April 2021 Accepted article published: 5 July 2021 Published online in Wiley Online Library:(wileyonlinelibrary.com) DOI 10.1002/jsfa.11413Uncovering the effects of kaolin on balancingberry phytohormones and quality attributesof Vitis vinifera grown in warm-temperateclimate regionsSara Bernardo,aLia-Tânia Dinis,aNelson Machado,bAna Barros,aMarta Pitarch-Bielsa,cAureliano C Malheiro,aAurelio Gómez-Cadenascand José Moutinho-Pereir aa*AbstractBACKGROUND: The application of kaolin particle lm is considered a short-term strategy against several environmental stres-ses in areas with a Mediterranean-like climate. However, it is known that temperature uctuations and water availability overthe season can jeopardize kaolin efciency in many Mediterranean crops. Hence, this study aims to evaluate the effects of kao-lin foliar application on berry phytohormones, antioxidant defence, and oenological parameters at veraison and harvest stagesof Touriga-Franca (TF) and Touriga-Nacional (TN) grapevines in two growing seasons (2017 and 2018). The 2017 growing sea-son was considered the driest (−147.1 dryness index) and the warmest (2705 °C growing degree days) of the study.RESULTS: In 2017, TF kaolin-treated berries showed lower salicylic acid (−26.6% compared with unsprayed vines) and abscisicacid (ABA) (−10.5%) accumulation at veraison, whereas salicylic acid increased up to 28.8% at harvest. In a less hot season, TNand TF kaolin-treated grapevines showed a twofold in ABA content and a threefold increase in the indole-3-acetic acid contentat veraison and lower ABA levels (83.8%) compared with unsprayed vines at harvest. Treated berries showed a decreased sugarcontent, without compromising malic and tartaric acid levels, and reactive oxygen species accumulation throughout berryripening.CONCLUSION: The results suggest kaolin exerts a delaying effect in triggering ripening-related processes under severe summerstress conditions. Treated berries responded with improved antioxidant defence and phytohormone balance, showing signif-icant interactions between kaolin treatment, variety, and developmental stage in both assessed years.

Der Weinbau ist einer Zunahme von Extremwetterereignissen und dem Klimawandel ausgesetzt und reagiert in besonderen Masse hierauf. Aufgrund der hohen soziookonomischen Bedeutung des Weinbausektors in Europa ist die Entwicklung von geeigneten Anpassungsstrategien zur Abschwachung der Auswirkungen des Klimawandels von groster Bedeutung fur seine kunftige Nachhaltigkeit und Wettbewerbsfahigkeit. In diesem Artikel sollen als Output des Forschungsprojektes Clim4Vitis (https://clim4vitis.eu/) einige mogliche kurzfristigen Anpassungsstrategien (Abbildung 1) zusammengefasst werden. Langzeitanpassungsstrategien werden in einem gesonderten Technical Review beschrieben.

The Mediterranean wine regions are characterized by a marked intra (and inter) annual climate variability, where high water deficits in the atmosphere and soil can develop, particularly during the summer. In addition, the climate change scenarios point to an intensification of these environmental conditions in the near future. Thus, the combination of survival strategies, which include the ability to reduce water losses, increase absorption or control dehydration, becomes an important tool for crop water management. Adaptation measures involving cultural practices must also be adopted to ensure the sustainability of the wine sector. One of the main adaptation viticultural practice is the selection of the training system. In this context, mature vines trained to two different systems in the Douro Demarcated Region (NE Portugal) were selected and several measurements (e.g. weather variables, soil moisture, leaf water potential, leaf area index, sap flow and trunk diameter fluctuations) were performed under variable soil water availability. The results highlight the key role of plant survival strategies, such as stomatal control and adjustment of the total leaf area, in order to reduce transpiration, as well as a nocturnal rehydration. Furthermore, and in terms of water dynamics, the results point to the effect of the shorter length of the hydraulic pathways of the Guyot-trained vines, in contrast to the higher trunk and the permanent horizontal cordon of the vines trained to spur pruned cordon. The research findings support the selection of the Guyot as a training system that is better adapted to the projected climate change in Mediterranean wine-producing regions.

At a local scale, kaolin particle-film technology is considered a short-term adaptation strategy to mitigate the adverse effects of global warming on viticulture. This study aims to evaluate kaolin application effects on photochemistry and related defence responses of Touriga Franca (TF) and Touriga Nacional (TN) grapevines planted at two Portuguese winegrowing regions (Douro and Alentejo) over two summer seasons (2017 and 2018). For this purpose, chlorophyll a fluorescence transient analysis, leaf temperature, foliar metabolites, and the expression of genes related to heat stress (VvHSP70) and stress tolerance (VvWRKY18) were analysed. Kaolin application had an inhibitory effect on VvHSP70 expression, reinforcing its protective role against heat stress. However, VvWRKY18 gene expression and foliar metabolites accumulation revealed lower gene expression in TN-treated leaves and higher in TF at Alentejo, while lipid peroxidation levels decreased in both treated varieties and regions. The positive kaolin effect on the performance index parameter (PIABS) increased at ripening, mainly in TN, suggesting that stress responses can differ among varieties, depending on the initial acclimation to kaolin treatment. Moreover, changes on chlorophyll fluorescence transient analysis were more pronounced at the Douro site in 2017, indicating higher stress severity and impacts at this site, which boosted kaolin efficiency in alleviating summer stress. Under applied contexts, kaolin application can be considered a promising practice to minimise summer stress impacts in grapevines grown in Mediterranean-like climate regions.

Kaolin protective effect was assessed in a white grapevine cultivar &lsquo, Cerceal&rsquo, in &lsquo, Alentejo&rsquo, Region (southeast Portugal) where plants face extreme conditions during the summer season. We addressed the hypothesis that kaolin effects lead to several changes in leaves, fruits, and wine characteristics on the primary and secondary metabolism. Results showed that kaolin reduces leaf temperature which provokes an improvement in physiological parameters such as net photosynthesis and water use efficiency. This protection interferes with berry color, leaving them more yellowish, and an increase in phenolic compounds were observed in all fruit tissues (skin, seed, and pulp). Additionally, both berry and wine characteristics were strongly affected, with an increase of tartaric and malic acid and consequently high total acidity, while the sugar concentration decreased 8.9% in berries provoking a low wine alcohol level. Results also showed that kaolin induces high potassium, magnesium, and iron, and low copper and aluminum concentrations. Moreover, the control wine showed higher content of esters related with hostile notes whereas wine from kaolin treated vines presented higher content of esters associated with fruity notes. Overall, the results strengthen the promising nature of kaolin application as a summer stress mitigation strategy protecting grapevine plants and improving fruit quality and creating more balanced wines.

Pine pitch canker (PPC), caused by Fusarium circinatum Nirenberg and O’Donnell, represents an important threat to conifer forests worldwide, being associated with significant economic losses. Although essential to develop disease mitigation strategies, little research focused on host susceptibility/resistance mechanisms has been conducted. We aimed to explore the response of a highly susceptible (Pinus radiata D. Don) and a relatively resistant (Pinus pinea L.) species to F. circinatum infection at different stages of infection. Morpho-physiological, hormonal and oxidative stress-related changes were assessed for each pine species and sampling point. Most of the changes found occurred in symptomatic P. radiata, for which an increased susceptibility to photoinhibition was detected together with decreased superoxide dismutase activity. Abscisic acid catabolism was activated by F. circinatum inoculation in both pine species, leading to the accumulation of the inactive dihydrophaseic acid in P. radiata and of the less-active phaseic acid in P. pinea. Hormone confocal analysis revealed that this strategy may be of particular importance at 6 d.p.i. in P. pinea, which together with photosynthesis maintenance to fuel defense mechanism, could in part explain the species resistance to PPC. These results are of great interest for the development of hormone-based breeding strategies or for the use of hormone application as inducers of resistance to F. circinatum infection.

The predicted accentuation of drought events highlights the importance of optimize plants capacity to tolerate drought, but also the capacity to recovery from it, especially in species, as olive tree (Olea europaea L.), that grows in particularly susceptible regions. Three different concentrations (10, 100 and 1000 μM) of salicylic acid (SA), a stress signaling phytohormone, was sprayed on 3-year-old potted olive trees subjected to three successive drought and rewatering events. Trees responses to SA application are concentration dependent, being 100 μM the most effective concentration to improve drought tolerance and recovery capacity. During drought events, this effectiveness was achieved by osmolytes accumulation, leaf water status maintenance, reduced photosynthetic systems drought-associated damages, and by optimizing shoot/root ratio. The better plant fitness during drought allowed a fast recovery of the physiological functions upon rewatering and reduced the necessity to invest in extra repair damages, allowing the regrowth. The intense abscisic acid (ABA) signal close to upper epidermis in stressed controls suggests a “memory” of the worst water status displayed by those plants. SA attenuated the limitation of total biomass accumulation imposed by drought, mainly in root system, increased water use efficiency and lead to a higher intense signal of indoleacetic acid (IAA) in leaves during recovery period. In summary, in a suitable concentration, SA demonstrate to be a promising tool to increase drought adaptability of olive trees.

Climate change is ongoing but the magnitude, extent and duration of its impacts is far from being known and, in particular, its consequence on Earth’s life is still under study. This article presents an overview about many research lines aiming to increase the resilience of chestnut in climate changes frame. In Europe, chestnut is considered a Mediterranean crop, facing nowadays significant heat and drought stresses with important consequences on species health. So, modelling its production is fundamental to project the future production and species area redistribution according to the new expected climatic conditions. These models are being developed based on specific meteorological variables and indices well related to different aspects and stages of the vegetative cycle. For example, the best range of growing degree days (GDD) for better ‘Judia’’s chestnut production was found to be within the range 2000-2200°D (between May and October). At orchard level, it is also demonstrated the benefits of preserving a good soil herbaceous vegetation cover, complemented with smart irrigation which can prevent the reduction on nut production by about 25-50%, depending on the annual precipitation, and increase the edible mushroom production. Results also clearly demonstrated the importance of bees on pollination, where a decrease of about 70% was observed when they were absent. New hybrid rootstocks are being developed (e.g., ColUTAD) aiming to face the new climatic context, namely to maximize photosynthesis rate at high air temperature (T100 = 34°C). Also in ‘Judia’, such plasticity was observed between genotypes from cold and warm localities. Calibers ranged between 58 and 107 nuts kg-1. The tolerance against blight disease (Chryphonectria parasitica) also significantly varied. Finally, additional mineral nutrition with silicon seems to lead to a lower mortality rate and phenol’s inhibition as well as to an increased tolerance of the specie to thermal and hydric stress. The addition of silicon appears to have protective effect on trees against ink (Phytophthora cinnamomi) and blight diseases as well as to prepare and adapt trees for a future climate that is expected to be warmer and drier.

Olive orchards, rainfed managed, are threatened by the current and predicted adverse environmental conditions, which change the yield and quality of olive products, largely known for its benefits to human health. To mitigate these problems, it is highly recommended to perform some adjustments in agronomic practices, such as the use of foliar sprays that cloud help the trees to cope with climate change. During two consecutive years, olive trees were pre-harvest sprayed with kaolin (KL) and salicylic acid (SA) to attenuate the adverse effects of summer stress. Olive yield was increased by 97% and 72% with KL and SA, respectively. Phenolics and antioxidant capacity of both olives and olive oil increased and decreased in the first and second year, respectively, in a closely association with the prevailing climatic conditions. The foliar sprays did not significantly affect the oil quality indices, free acidity, peroxide value and K232 coefficient and decreased the K270 coefficient. This study strongly suggests that the applied products might be effective in mitigating the adverse environmental conditions, without substantial changes in fruit and olive oil quality. Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/ 52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. INTERACT project - "Integrative Research in Environment, Agro-Chains and Technology", no. NORTE-01-0145- FEDER-000017, in its lines of research entitled ISAC, co-financied by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020). info:eu-repo/semantics/publishedVersion

Knowledge about short-term climate change adaptation strategies for Mediterranean vineyards is needed in order to improve grapevine physiology and yield-quality attributes. We investigated effects of kaolin-particle film suspension on water relations, photosynthesis and oxidative stress of field-grown grapevines in the Douro region (northern Portugal) in 2012 and 2013. Kaolin suspension decreased leaf temperature by 18% and increased leaf water potential (up to 40.7% in 2013). Maximum photochemical quantum efficiency of PSII was higher and the minimal chlorophyll fluorescence was lower in the plants sprayed by kaolin. Two months after application, net photosynthesis and stomatal conductance at midday increased by 58.7 and 28.4%, respectively, in treated plants. In the same period, kaolin treatment increased photochemical reflectance, photosynthetic pigments, soluble proteins, soluble sugars, and starch concentrations, while decreased total phenols and thiobarbituric acid-reactive substances. Kaolin application can be an operational tool to alleviate summer stresses, which ameliorates grapevine physiology and consequently leads to a higher yield.

The present research aimed to evaluate the water dynamics of grapevines trained in Cordon and Guyot systems by coupling sap flow and trunk diameter measurements under Mediterranean climate conditions. The study was conducted in a vineyard with Touriga-Nacional located at the Douro Valley, Portugal, during 2017. The results showed daily trunk diameter fluctuations (TDFs), with the contraction, recovery and increment phases and higher sap flow (SF) rates at earlier stages. Under harsh pedoclimatic conditions, SF was reduced and TDF flattened. Rehydration and stomatal mechanisms were mostly associated with these responses. Guyot vines showed higher changes in TDF for the same SF values, whereas the TDFs of Cordon vines remained practically unchanged over maturation. Guyot vines generally showed increased values of cumulative increment and maximum daily trunk shrinkage. Although Guyot vines had a similar leaf area index (LAI), they showed higher SF/LAI ratios than Cordon vines. These results highlight the e ect of the shorter length of the hydraulic pathways of the Guyot training system, in contrast to the higher trunk and the permanent horizontal branch (cordon) of the Cordon training system, indicating good adaptation to local pedoclimatic conditions. The study pointed to the complementary use of both techniques in the evaluation of grapevine water dynamics info:eu-repo/semantics/publishedVersion

Increasing consciousness regarding the nutritional value of olive oil has enhanced the demand for this product and, consequently, the expansion of olive tree cultivation. Although it is considered a highly resilient and tolerant crop to several abiotic stresses, olive growing areas are usually affected by adverse environmental factors, namely, water scarcity, heat and high irradiance, and are especially vulnerable to climate change. In this context, it is imperative to improve agronomic strategies to offset the loss of productivity and possible changes in fruit and oil quality. To develop more efficient and precise measures, it is important to look for new insights concerning response mechanisms to drought stress. In this review, we provided an overview of the global status of olive tree ecology and relevance, as well the influence of environmental abiotic stresses in olive cultivation. Finally, we explored and analysed the deleterious effects caused by drought (e.g., water status and photosynthetic performance impairment, oxidative stress and imbalance in plant nutrition), the most critical stressor to agricultural crops in the Mediterranean region, and the main olive tree responses to withstand this stressor.

In the latest decades, global warming impacts become an emergent issue, and short-term techniques such as kaolin have been proposed to mitigate summer stress effects on Mediterranean viticulture. Nevertheless, the impact of this technology on grape berry composition, particularly on different fractions of whole berry (skin, pulp, and seed) is not yet studied, being these data crucial to the expansion of waste and by-product industry. Thus, the purpose of the present study was to fulfill the identified gap of knowledge by investigating how a pre-veraison kaolin (5% w/v) exogenous application may impact secondary metabolites and antioxidant capacity (ABTS + and DPPH methods) at veraison and maturation, in whole berries and their fractions (skin, pulp, and seed), from seven red varieties (‘Touriga Franca’, ‘Touriga Nacional’, ‘Tinta Francisca’, ‘Vinhao’, ‘Grenache’, ‘Borracal’, and ‘Cornifesto’) under Mediterranean conditions conjugated with global warming. Afterwards, biometric, color and oenological parameters (soluble solids, pH, acidity, and soluble protein) were also quantified in whole berries. Our findings indicate that kaolin increased the berry size (up to 62.2 %) which reduced the skin-to-pulp weight ratio and consequently the anthocyanins contents (reaching − 41.7 %). Additionally, particle film reduced leaf temperature (until – 11.78 %) avoiding thermal stress which seems to decrease the production of proteins in grape berries treated (up to – 27.01 %), indicating a potential reduction of heat shock proteins production. Our results enlighten that it was crucial to analyze the several fractions of grape berries separately, because output resulting from the whole berry might lead to an inaccurate conclusion. In this vein, although often no changes were reported in the whole berry, when analyzing their specific fractions, we found that kaolin enhanced the production of secondary metabolites and antioxidant capacity in the seed (reaching 49,40 and 48.29 %, respectively), leading to a positive influence on berry quality which might be favorable to industrial by-products expansion. The findings also support that kaolin can represent a resilience strategy aiming to improve berry quality under the changing climatic scenario.

Extreme conditions, such as drought, high temperature, and solar irradiance intensity, are major factors limiting growth and productivity of grapevines. In a field experiment, kaolin particle film application on grapevine leaves was examined during two different summer conditions (in 2012 and 2013) with the aim to evaluate benefits of this practice against stressful conditions hindering photochemical processes. We used chlorophyll a fluorescence to investigate attached leaves. Two months after the application, during the hottest midday, the kaolin-treated plants showed by the JIP test significantly higher quantum yield of PSII photochemistry, flux ratios, maximum trapped excitation flux of PSI, absorption flux, electron transport flux, maximum trapped energy flux per cross section, and performance index than plants under control conditions in the warmer year. On the contrary, the treated plants showed a lower initial slope of relative variable fluorescence and a decrease in the absorption and electron transport per cross section. The JIP test showed higher efficiency of PSII in the plants treated with kaolin mainly in 2013 (higher temperature and drought). Our results supported the hypothesis that the accumulation of active PSII reaction centres was associated with decreased susceptibility to photoinhibition in the kaolin-treated plants and with more efficient photochemical quenching. Grapevines in the Douro Region seems to profit from the kaolin application.

Regarding the foreseeing climate change is reasonable to expect harmful consequences to olive tree (Olea europaea L.), an iconic species of Mediterranean region. Thus, the selection of practices that allow a better drought resistance and recovery capacity needs the immediate attention of scientific community. This study evaluates the strategies adopted by young potted olive trees, subjected to three cycles of drought and rewatering, in the presence of a reflective clay, kaolin (KL). The results demonstrated that KL induced shade-related leaf structural changes and was effective in keeping leaf water status during the most stressful periods. In general, photosynthetic activity of sprayed plants was improved by the alleviation of drought-induced stomatal and non-stomatal limitations. Moreover, during stress imposition sprayed leaves showed reduced oxidative damages, allowing lower investment in antioxidant defences. Furthermore, sprayed plants also had lower nighttime water losses due to inferior nighttime stomatal conductance, and are able to maintain higher respiration rates. Upon rewatering, the shaded effect conferred by KL limited gas exchange restauration, but improved the plants' capacity to restore the metabolic functions. In spite of the induced physiological and biochemical changes, no significant differences were found in whole-plant water use efficiency and plant biomass accumulation, possibly by the attenuation of photosynthesis restauration during the recovery events. In conclusion, the changes induced by KL might be beneficial under severe conditions, as on realistic Mediterranean field environments.

Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.jplph.2018.02.004., Water scarcity is associated with extreme temperatures and high irradiance, and significantly and increasingly affects grapevine yield and quality. In this context, the foliar application of kaolin, a chemically inert mineral that greatly reflects ultraviolet and infrared radiations, as well as, in part, photosynthetically active radiation, has recently been shown to decrease photoinhibition in mature leaves. Here, the influence of this particle film on grapevine leaf metabolome and carbohydrate metabolism was evaluated. Molecular mechanisms underlying photoassimilate synthesis, metabolism and transport capacity were assessed by targeted transcriptional analyses and enzymatic activity assays. Kaolin application increased sucrose concentration in leaves and sucrose transport/phloem loading capacity, as suggested by the stimulation of the transcription of sucrose transporters VvSUC12 and VvSUC27 in these source organs. While the biosynthesis of sucrose increased, as evidenced by higher sucrose content and sucrose phosphate synthase (SPS) activity in leaves, the concentration of transitory starch before the dark period remained unaltered, despite a higher total amylolytic activity in the leaves of kaolin-treated plants. Metabolomic analysis by GC-TOF-MS showed that the application of kaolin enhanced the amounts of simple sugars, including fructose, maltose, xylulose, xylose, sophorose, ribose and erythrose; sugars-phosphate, like mannose-6-Pi, hexose-6-Pi, glucose-6-Pi, glucose-1-Pi, glycerol--Pi and fructose-6-Pi; polyols, like xylitol, maltitol, lactitol, glycerol, galactinol and erythritol; organic acids and amino acids., The work was supported by European Union Funds (FEDER/ COMPETE-Operational Competitiveness Programme – INNOVINE – ref. 311775, Enoexcel – Norte – 07-0124-FEDER-000032, and INTERACT – NORTE-01- 0145-FEDER-000017 – Linha VitalityWine – ON 0013), and by Portuguese national funds (FCT-Portuguese Foundation for Science and Technology) under the project UID/AGR/04033/2013. Artur Conde was supported by INTERACT – NORTE-01- 0145-FEDER-000017 – Linha VitalityWine – ON 0013 (BPD/UTAD/INTERACT/VW/218/ 2016). Richard Breia was supported by FCT under the fellowship PD/ BD/113616/2015., info:eu-repo/semantics/publishedVersion

Background Cropping practices focusing on agronomic water use efficiency and their impact on quality parameters must be investigated to overcome constraints affecting olive groves. We evaluated the response of olive trees (Olea europaea, cv. 'Cobrancosa') to different water regimes: full irrigation (FI, 100% crop evapotranspiration (ETc )), and three deficit irrigation strategies (DIS) (regulated (RDI, irrigated with 80% of crop evapotranspiration (ETc ) in phases I and III of fruit growth and 10% of ETc in the pit hardening stage), and two continuous sustained strategies (SDI) - a conventional SDI (27.5% of ETc ), and low-frequency irrigation adopted by the farmer (SDIAF, 21.2% of ETc ). Results The effects of water regimes on the plant water status, photosynthetic performance, metabolite fluctuations and fruit quality parameters were evaluated. All DIS treatments enhanced leaf tissue density; RDI and SDI generally did not affect leaf water status and maintained photosynthetic machinery working properly, and the SDIAF treatment impaired olive tree physiological indicators. The DIS treatments maintained the levels of primary metabolites in leaves, but SDIAF plants showed signs of oxidative stress. Moreover, DIS treatments led to changes in the secondary metabolism, both in leaves and in fruits, with increased total phenolic compounds, ortho-diphenols, and flavonoid concentration, and higher total antioxidant capacity, as well higher oil content. Phenolic profiles showed the relevance of an early harvest in order to obtain higher oleuropein levels with associated higher health benefits. Conclusion Adequate DIS are essential for sustainable olive growing, as they enhance the competitiveness of the sector in terms of olive production and associated quality parameters. © 2019 Society of Chemical Industry.