Grapevine Quality Research Articles

Thompson Seedless Grapevines Growth and Quality as Affected by Glutamic Acid, Vitamin B, and Algae

Grapevine (Vitis vinifera L.) quality and growth are affected by the foliar fertilization. Algae extract, glutamic acid, and vitamin B are known as foliar fertilizer but there is little information available about the best combinations of these materials for grapevine. Here, 2-year field study in a randomized complete block design (RCBD) were conducted to study the influence of foliar applications of vitamin B, glutamic acid, and algae (Amphora ovalis) extract on Thompson Seedless grapevines (Vitis vinifera L.) growth and yield. The growth, yield, and quality of grapevine were affected significantly (P < 0.05) by the different treatments. The foliar application of vitamin B, glutamic acid, and algae increased the pruning wood, total chlorophyll, leaf area, and fruit yield compared with the control. In addition, these treatments induced an increase in the concentrations of N, P, and K. The berries quality characteristics of the sprayed vines were significantly better than non-treated ones. Based on the obtained results, the foliar application of glutamic acid, vitamin B complex, and algae besides of their combinations has positive effects on the growth of grapevine plants and berry quality.

Overexpression of VaWRKY12, a transcription factor from Vitis amurensis with increased nuclear localization under low temperature, enhances cold tolerance of plants.

Overexpression of VaWRKY12, whose nuclear translocation increased under low temperature, enhanced the cold tolerance of Arabidopsis and grapevine calli and significantly increased the expression of antioxidant-related genes. Low temperature causes injuries to buds during winter and to young shoots during early spring, thereby affecting grapevine quality and yield. Understanding the regulatory mechanisms of cold stress responses is essential for the breeding of new grapevine cultivars with excellent cold tolerance. Previous studies indicated that WRKY family genes are induced by low temperature in grapevine, but their function in cold stress responses was not clear. Here, a cold-induced WRKY gene, named VaWRKY12, was cloned from Vitis amurensis, which displays remarkable cold tolerance. An atypical transmembrane (TM) region was found in its C-terminal region. Transient expression assays showed that VaWRKY12 was localized in the nucleus and cytoplasm at normal temperature but only in the nucleus after cold treatment. By contrast, a truncated version of VaWRKY12 without the TM region was found specifically in the nucleus at normal temperature, and its binding activity to tandem W-box elements in yeast was stronger than that of VaWRKY12, indicating that the TM region might affect the location and function of VaWRKY12. Overexpression of VaWRKY12 enhanced the cold tolerance of transformed Arabidopsis and grapevine calli. Transcriptome data revealed that the expression of genes encoding antioxidant enzymes, including peroxidases and glutathione S-transferases, was upregulated after cold treatment in VaWRKY12-overexpressing grapevine calli compared to the control calli. This study identifies candidate target genes as a basis for further studies on the roles of VaWRKY12 in cold stress responses in grapevine.

Effects of seawater irrigation on fruit quality of grapevine, soil properties and microbial diversity

Extensive researches have been conducted over the decades to investigate the effects of seawater on many crop plants, either by irrigation or foliar spray, in an attempt to enhance yield and quality, but there are few studies on the effects of seawater irrigation on soil properties. The purpose of this study was to determine the effects of seawater irrigation on the fruit quality of Cabernet Sauvignon grapevines, soil pH, soil salinization, soil bulk density properties and soil microbial diversity. Field experiments were conducted using seawater (10% concentrations) during the fruit expansion period, the early veraison period, the veraison period and the late veraison period in Penglai (pH 6.5–6.7). Seawater irrigation led to increased levels of fruit soluble solids, phenolic content, anthocyaninand sugar/acid ratio, resulting in slowly-increased pH values of soils. After 4 years of continuous seawater irrigation, the pH value of the 0–20 cm soil layer increased 0.24 units at the vineyard of the Guobin Winery and increased 0.17 and 0.18 units after one and two years of seawater irrigation, respectively, at the vineyard of the COFCO Winery. Moreover, seawater irrigation did not affect soil properties, since soil bulk density, specific gravity and porosity did not differ significantly from the control soil. Furthermore, seawater irrigation had less effect on the types of soil microbial communities. The results suggest that combined with rainfall, seawater irrigation could be useful for improving fruit quality and soil pH without inducing secondary soil salinization problems, and seawater irrigation could be used in acidic vineyard soils.

VINESYM: an integrated vine and grapevine mathematical model for vegetative development and production quality forecast

The present work deal with the development of a mathematical model able to predict, using time dependent meteorological data, soil and vine characteristics, the growing of a vine and grapevine in terms of leaf area, shoot length, fruit and vegetative mass and finally sugar and acid content of the berry. The model is based upon a source-sink relationship approach, integrated with a soil-atmosphere model, where water accumulation in soil, sap flow across vine are coupled with potential carbon demand functions to directly consider possible water and temperature stresses. The model includes also a N2 sink-source approach, limiting growth rate following N2 availability. Finally, a mechanistic model to evaluate sugar accumulation and a correlation-based model for acid concentration evaluation in the berry is coupled with vegetative growth, to provide the information required to manage vineyard operations and evaluate the impact to the potential wine quality. The primary distinctive trait of this model is then the integration and feedback among prediction of grapevine quality model (sugar an acid content) and vegetative growth model, using a common initial ad boundary conditions data set.

A 30-years vineyard trial: Plant communities, soil microbial communities and litter decomposition respond more to soil treatment than to N fertilization

Soil management strategies in viticulture should not only aim to optimize yield and quality of grapevines, but also sustain soil biodiversity and soil functioning. Here, we report on the combined effects of soil treatment and nitrogen fertilization on parameters related to soil fertility and litter decomposition, as well as plant, fungal, and bacterial communities in a long-term vineyard experiment, where these management practices have been applied since 1987. Plots in this vineyard (Hesse, Germany) were treated with different yearly amounts of nitrogen fertilizer (0, 30, 60, 90, 120, and 150 kg N ha−¹) with two types of inter-row soil treatment (tillage vs. permanent cover). We analyzed soil properties of the topsoil, decomposition parameters using the Tea Bag Index approach, the inter-row plant community, and microbial communities (bacteria and fungi) by next generation sequencing techniques.Long-term tillage decreased soil carbon and nitrogen levels as well as some plant available nutrients, whereas soil pH and plant available phosphorus increased. Elevated amounts of nitrogen fertilization slightly increased soil carbon and nitrogen levels. Relative mass loss of tea bag content due to decomposition was decreased, while stabilization of labile litter components was increased by tillage, compared to permanent cover treatments. Plant community patterns were changed by soil treatment with tillage inter-rows exhibiting annual, ruderal species and being more diverse compared to permanent cover inter-rows. Relative abundance of several bacterial phyla and fungal orders responded strongly to soil treatment. Changes in soil pH and levels of phosphorus could partly explain the underlying mechanisms involved in shifts of bacterial and fungal communities, respectively. In contrast, long-term nitrogen fertilization only slightly shifted plant and microbial community composition. This study shows that over the long-term, soil treatment strongly affects soil functioning and biodiversity, exceeding the effect of even high nitrogen fertilization levels.

Productivity and chemical quality of grapevines cultivated in agroecological system under subtropical climate

Abstract The productive potential of grapevine cultivars recently released in the market, especially for preparation of 100% grape juices, must be proved on the different Brazilian soil and climatic conditions of production, focusing on the Southwest of Paraná. The objective of this study was to evaluate the main yield components and chemical attributes of the juice of the following grapevine cultivars: Bordô, BRS Carmem, BRS Lorena, BRS Magna, BRS Rubea, BRS Violeta, Concord, Concord Clone 30, Isabel, Isabel Precoce, Moscato Bailey, Moscato Embrapa, Niagara Branca, Niagara Rosada and Seibel 5455. Paulsen 1103 was the rootstock used. The study was conducted during two harvests, 2015/2016 and 2016/2017, in Dois Vizinhos, Paraná State, Brazil. Due to the crop, we determined the number of bunches per plant, fresh biomass of bunches (g) and the estimates of productivity (kg/plant and ton/ha). We extracted the juice of cultivars to evaluate soluble solids (SS) contents, pH and titratable acidity (TA), as well as the ratio. The cultivars BRS Violeta, Isabel Precoce and Seibel 5455 were the most productive. The cultivars BRS Rúbea, BRS Violeta, Isabel, Moscato Embrapa, Moscato Bailey, Niagara Branca and Niagara Rosada have desirable soluble solids contents, pH and titratable acidity for preparation of 100% grape juices of quality in Dois Vizinhos and microregion. The best year-harvest of cultivation was 2016/2017.

Effects of a biostimulant derived from the brown seaweed Ascophyllum nodosum on ripening dynamics and fruit quality of grapevines

Abstract Most modern and traditional grape-growing regions are facing challenging times due to the unpredictability of weather conditions and warming trends. Innovative and sustainable tools such as seaweed-based biostimulants may play a key-role in the development of environment-friendly viticultural strategies to improve yields, biotic/abiotic stress tolerance and fruit and wine quality. A sprayable Ascophyllum nodosum extract was tested on grapevines cv. Sangiovese grown under Mediterranean conditions (central Italy) and on grapevines cv. Pinot Noir and Cabernet Franc within a cool-climate viticulture region (Michigan, USA). The product was sprayed on the canopies at label doses (1.5 kg/ha) five times during the season, starting two weeks before veraison. The seaweed extract did not affect leaf gas exchanges, yield or cluster and berry size, but hastened veraison, improved anthocyanins accumulation in all cultivars and increased phenolic content particularly in Sangiovese. Therefore, medium-late application of the seaweed extract can be a simple way to favour chromatic and chemical proprieties of grapes and wines. This is the first report of positive effects of Ascophyllum nodosum extracts on the quality of cultivated wine grapes. The adoption of the technique can be particularly suitable to cool-climate viticulture, especially as it pertains to short growing seasons and genotypes with a limited phenolic profile.

Vineyard microbiome variations during different fertilisation practices revealed by 16s rRNA gene sequencing

Fertilisation practices are increasingly recognised as factors influencing the soil microbial communities, and they have a pivotal role in maintaining soil fertility and regulating ecosystem functions. Soil microbial communities react to different fertilisation practices and environmental conditions. It is known that vineyards harbour a specific set of microorganisms. The vineyard microbiome has been extensively investigated to decipher the associated microbial populations in soil, as well as the dynamics of microorganisms in grapes and the phyllosphere. Wine harbours a wide range of microorganisms originating from the belowground environment, many of which are recognised for their role in driving the grapevine quality. This study evaluates the long term-effect of two fertilisation practices (mineral, MD and organo-mineral, OMD) on the soil bacterial community in a nine-year-old vineyard. Sequencing was done on environmental DNA soil samples to amplify the hypervariable region V3–V4 of the 16S rRNA gene using an Illumina platform. The results provide information on the distribution of different bacterial groups in relation to fertilisation practices and temporal variability. Our work reveals that the assortment and distribution of microorganisms in agricultural systems depend on several factors, underlining the importance of fertilisation strategy in the overall management of soil quality and fertility.

Grapevine quality: A multiple choice issue

Abstract Over decades, the concept of grape quality has evolved emphasizing its multidisciplinary nature and that the same “desired quality” might correspond to even strikingly different compositional patterns. The review takes a long journey throughout the multiple factors impinging on grape quality, not excluding also sections devoted to table grapes. It starts with a through survey on the genetic factors influencing grape quality focusing on diversity in different compositional traits (sugar, organic acid, pH, phenolics and aromas) relating to cultivars and clones. Then, most recent knowledge about the effects of soil characteristics, nutrients, light, temperature and water availability, as standalone factors or in interaction, on grape quality are summarized. The more applied section of the review introduces the very much debated yield-quality relationship that, over years, is being interpreted with more flexibility and with greater consensus for an “optimal yield range” that within a given context can anyway reach the desired quality. The impact of the main summer pruning operations (leaf removal, shoot and cluster thinning, shoot trimming) is reviewed and special care taken to highlight most recent contributions with adjusted summer pruning developed to either adapt to climate change issues or to induce specific composition patterns. Review ends with a quick survey on methods nowadays available for fast, non-destructive grape composition assessment.

Grapevine quality characteristics as affected by the training system

The aim of this research, conducted during the 2015 growing season, was to compare two different training systems, Gobelet (bush vine) and pruned upward vertical shoot positioning (VSP), through the analysis of canopy efficiency: vegetative and productive activity, as well as physiological behavior. Leaf area, shoots and light interception, and single leaf gas exchanges were measured. Furthermore, investigations in productive activity, qualitative and quantitative grape characteristics were carried out: berry samples were collected from the veraison to harvest, and sugar content, titratable acidity, pH, extractable anthocyanins and polyphenols were analyzed. The main differences between Gobelet and VSP were related to the enhancements of vegetative activity and yield (berry and cluster weights), generally due to improved exposed leaf area and hence light interception. Gobelet training system may be indicated in climates characterized by high photosynthetic active radiation (PAR), to increase yields while preserving the quality of the grapes.

Retraction Note to: Physiological comparative study of six wild grapevine (Vitis sylvestris) accession responses to salinity

Salinity problems for vineyards are in concerns, especially in coastal areas where several aquifers are reported to be affected by seawater intrusion and agricultural contamination. Saline irrigation affects growth, yield, and fruit quality of grapevines. Exploring germplasm base through wild ancestors of the target species is a novel adopted strategy to increase crop tolerance to irrigation with saline water. The effects of salt on growth, organic and inorganic solute accumulations, and chlorophyll florescence were studied on 3-month-old plants of six Tunisian wild grapevines with the objective to identify salt tolerance mechanisms and select tolerant genotypes. Potted plants were grown under controlled conditions and irrigated for 14 days with 0, 100, and 150 mM NaCl nutrient solution. Parameters analyzed were related to growth, water relations, mineral nutrition, and chlorophyll fluorescence. Several processes are operating either at the whole plant or at cell level. They appear to be involved in salt tolerance of wild grapevines and are more efficient in tolerant accessions. Salt adversely affects plant growth and plant nutrition. Reductions of shoot growth rate (relative growth rate, day−1) reached 49% of control since 100 mM NaCl. They were assigned to stomatal closure and alteration of potassium nutrition and photochemistry. There were significant differences (P < 0.05) within accessions, Tebaba was the most tolerant and Houamdia the most sensitive, while the others were intermediate.

Differences in chemical composition of 'Plavac mali' grape berries

Evaluation of differences in yield and quality of grapevine is often based on the random samples of berries harvested on the same date. Due to differences in ripeness of berries from the same cluster, and among berries from different clusters of the same vine, the determined differences among examined treatments (clones, agricultural practices etc.) based on random berry samples may be over- or underestimated. The aims of this study were to determine: (1) differences among three 'Plavac mali' clones in the proportion of berries of different density classes (sugar concentration level) using the flotation method; (2) differences in berry weight and chemical composition among density classes of the same clone, and (3) differences between clones of the same density class. Significant differences were determined for all observed characteristics, among different berries density classes and clones. The results obtained indicate that berry samples used to compare different clones should be, to the greatest possible extent, at the same level of ripeness, as this significantly effects chemical composition. This can be achieved using the density separation of berries with the simple flotation method presented in this study. The presented results could be useful in the future improvement of clonal selection methodology as well as in improvement of sampling strategy for other types of researches.

Radiometric properties, vine physiology and yield parameters of irrigated ‘Sublima’ table grape under different plastic films in South Italy

Covering plastic materials are used to protect vines and grapes from adverse weather conditions and to influence the microclimate, aiming at modifying the growing conditions in comparison with those in open field. This technique may advance or delay berry ripening in table grapes according to the period of covering. The radiometric properties of the plastic covering films influence canopy microclimate, leaf functioning, yield components and berry quality of grapevines. Three polyethylene films were tested in Southern Italy during the 2012 season: two commercial films, coded “YELLOW” and “NEUTRAL” according to their color, and an experimental film coded “BASF”, as it was provided by BASF Italia SpA. The plastic films were tested on a seedless grapevine variety (Vitis vinifera 'Sublima Seedless') grown with three different irrigation treatments, i.e. V1, V2 and V3 corresponding to 100, 80 and 50% of the estimated vine evapotranspiration. Radiometric tests were carried out in laboratory on the plastic films at the beginning and at the end of the vegetation period. In the field, environmental parameters, such as photosynthetic photon flux, air temperature and relative humidity, were recorded. Vine water status and leaf gas exchange were measured during berry growth. At harvest, the vine productivity and the grape quality were assessed. At the beginning of the growing season the plastic films were characterized by PAR total transmissivity coefficient equal to 86.3% for the BASF film and 86.0% for YELLOW films; this coefficient was lower for NEUTRAL film (81.8%). Concerning the solar IR transmissivity coefficient, the YELLOW film was characterized by the highest value (90.0%), while BASF film by the lowest one (81.0%). Vines that received the lowest irrigation volume showed the worst water status and the lowest rates of leaf gas exchange, as expected; moreover, they limited their leaf area expansion. Leaves of vines under NEUTRAL film showed a tendency for a higher stomatal conductance and leaf transpiration, but not for a higher photosynthetic rate. The cluster weight was reduced on vines that received the lowest irrigation volume, while the berry reached the highest sugar content. The skin color parameters (L*, a*, b*) were influenced by the different irrigation treatments and the different covering plastic films.

RETRACTED ARTICLE: Physiological comparative study of six wild grapevine (Vitis sylvestris) accession responses to salinity

Salinity problems for vineyards are in concerns, especially in coastal areas where several aquifers are reported to be affected by seawater intrusion and agricultural contamination. Saline irrigation affects growth, yield, and fruit quality of grapevines. Exploring germplasm base through wild ancestors of the target species is a novel adopted strategy to increase crop tolerance to irrigation with saline water. The effects of salt on growth, organic and inorganic solute accumulations, and chlorophyll florescence were studied on 3-month-old plants of six Tunisian wild grapevines with the objective to identify salt tolerance mechanisms and select tolerant genotypes. Potted plants were grown under controlled conditions and irrigated for 14 days with 0, 100, and 150 mM NaCl nutrient solution. Parameters analyzed were related to growth, water relations, mineral nutrition, and chlorophyll fluorescence. Several processes are operating either at the whole plant or at cell level. They appear to be involved in salt tolerance of wild grapevines and are more efficient in tolerant accessions. Salt adversely affects plant growth and plant nutrition. Reductions of shoot growth rate (relative growth rate, day−1) reached 49% of control since 100 mM NaCl. They were assigned to stomatal closure and alteration of potassium nutrition and photochemistry. There were significant differences (P < 0.05) within accessions, Tebaba was the most tolerant and Houamdia the most sensitive, while the others were intermediate.

Water deficit effects on the molecular processes, physiology and quality of grapevine

Water deficit effects on the molecular processes, physiology and quality of grapevine

Ecophysiology, Vigour, Berry and wine Quality of Grapevines Growing on and off Heuweltjies

Heuweltjies are unique landscape features putatively created by the termite Microhodotermes viator through their burrowing and nest-building activities. They have been closely examined in the natural veld of the Western Cape in the recent past and are the focus of many ecological studies, but their effect in cultivated landscapes (e.g. vineyards and orchards) has remained unexplored. This study addresses the vigour and physiology of vines growing on and off heuweltjies, as well as the wine emanating from these vines. This study was conducted on Cabernet Sauvignon and Shiraz in two climatic regions of the Western Cape, namely Stellenbosch (Mediterranean climate) and Robertson (semi-arid climate) respectively, to better understand how differences in heuweltjie characteristics correspond to differences in rainfall and temperature. Through the use of ANOVAs and Fisher’s LSD post hoc tests to indicate statistical significance, it was apparent that the soil on and off heuweltjies differed significantly in respect of several physical and chemical properties. Consequently, soil water content was more favourable on heuweltjies, especially in the Stellenbosch area, where only supplementary irrigation was applied. Heuweltjies induce substantial changes in grapevine vigour and grape composition. Differences in grapevine physiology between heuweltjie and non-heuweltjie plots were subtle, but vine vigour was severely altered on the heuweltjieassociated vines, exhibiting excessive vegetative growth in Stellenbosch and leading to variations in berry and wine characteristics on and off the heuweltjies. The opposite was observed in the semi-arid climate of Robertson. The presence of heuweltjies in vineyards presents an opportunity to produce and market wines with a difference in respect of their characteristics and unique origin.

Expression of Vitis amurensis NAC26 in Arabidopsis enhances drought tolerance by modulating jasmonic acid synthesis.

The growth and fruit quality of grapevines are widely affected by abnormal climatic conditions such as water deficits, but many of the precise mechanisms by which grapevines respond to drought stress are still largely unknown. Here, we report that VaNAC26, a member of the NAC transcription factor family, was upregulated dramatically during cold, drought and salinity treatments in Vitis amurensis, a cold and drought-hardy wild Vitis species. Heterologous overexpression of VaNAC26 enhanced drought and salt tolerance in transgenic Arabidopsis. Higher activities of antioxidant enzymes and lower concentrations of H2O2 and O2 (-) were found in VaNAC26-OE lines than in wild type plants under drought stress. These results indicated that scavenging by reactive oxygen species (ROS) was enhanced by VaNAC26 in transgenic lines. Microarray-based transcriptome analysis revealed that genes related to jasmonic acid (JA) synthesis and signaling were upregulated in VaNAC26-OE lines under both normal and drought conditions. VaNAC26 showed a specific binding ability on the NAC recognition sequence (NACRS) motif, which broadly exists in the promoter regions of upregulated genes in transgenic lines. Endogenous JA content significantly increased in the VaNAC26-OE lines 2 and 3. Our data suggest that VaNAC26 responds to abiotic stresses and may enhance drought tolerance by transcriptional regulation of JA synthesis in Arabidopsis.

Growth, Yield and Fruit Quality of Grapevines under Organic and Biodynamic Management.

The main objective of this study was to determine growth, yield and fruit quality of grapevines under organic and biodynamic management in relation to integrated viticultural practices. Furthermore, the mechanisms for the observed changes in growth, yield and fruit quality were investigated by determining nutrient status, physiological performance of the plants and disease incidence on bunches in three consecutive growing seasons. A field trial (Vitis vinifera L. cv. Riesling) was set up at Hochschule Geisenheim University, Germany. The integrated treatment was managed according to the code of good practice. Organic and biodynamic plots were managed according to Regulation (EC) No 834/2007 and Regulation (EC) No 889/2008 and according to ECOVIN- and Demeter-Standards, respectively. The growth and yield of the grapevines differed strongly among the different management systems, whereas fruit quality was not affected by the management system. The organic and the biodynamic treatments showed significantly lower growth and yield in comparison to the integrated treatment. The physiological performance was significantly lower in the organic and the biodynamic systems, which may account for differences in growth and cluster weight and might therefore induce lower yields of the respective treatments. Soil management and fertilization strategy could be responsible factors for these changes. Yields of the organic and the biodynamic treatments partially decreased due to higher disease incidence of downy mildew. The organic and the biodynamic plant protection strategies that exclude the use of synthetic fungicides are likely to induce higher disease incidence and might partially account for differences in the nutrient status of vines under organic and biodynamic management. Use of the biodynamic preparations had little influence on vine growth and yield. Due to the investigation of important parameters that induce changes especially in growth and yield of grapevines under organic and biodynamic management the study can potentially provide guidance for defining more effective farming systems.

Effects of climate change including elevated CO2 concentration, temperature and water deficit on growth, water status, and yield quality of grapevine (Vitis vinifera L.) cultivars

In the Mediterranean area, climate change is associated with atmospheric CO2 concentration increases, enhanced temperatures and scarce water availability, limiting seriously crop yield and decreasing quality. The aim of this study was to investigate the effects of elevated CO2, elevated temperature and water deficit, acting individually and/or interacting, on vegetative and reproductive growth, substrate and plant water status, and must quality in fruit-bearing cuttings of two grapevine (Vitis vinifera L.) cultivars (red and white Tempranillo). In four temperature gradient greenhouses, eight treatments were applied, from fruit set to maturity: CO2 level (400 versus 700μmolmol−1), temperature (ambient versus ambient +4°C), and water availability (full irrigation versus cyclic drought). Effects of climate change on grape yield and quality were cultivar dependent. Generally, red Tempranillo had more vegetative growth and grape yield than the white cultivar. Also, grape yield was less affected by the treatments than vegetative growth. Drought, especially under elevated temperature, drastically reduced vegetative growth, bunch fresh and dry weights in both cultivars. Interestingly, elevated CO2 attenuated these negative effects of drought. The effects of climatic factors on yield were not associated with a worse water status of the vegetative or reproductive organs. In red Tempranillo, the combination of elevated CO2, elevated temperature and drought reduced total polyphenol index (TPI), malic acid and increased color density, but did not modify anthocyanin concentration. In white Tempranillo, the combined action of the three factors associated with climate change modified only tartaric acid. In this latter cultivar, drought increased TPI under ambient temperature, regardless of CO2 level, when compared with full-irrigated plants. In conclusion, climate change-related factors (elevated CO2, elevated temperature and water deficit) individually (especially drought) and/or interacting affected to different extent red and white Tempranillo vegetative growth and yield. Drought combined with elevated temperatures reduced grapevine performance, and elevated CO2 mitigated such deleterious effect.

Yield and mineral composition of grapevine (Vitis vinifera L. cv. Karaerik)as affected by boron management

Boron (B) deficiency is widespread in the northeastern Anatolian region of Turkey. This could impact the production and quality of grapevine (Vitis vinifera L. cv. Karaerik). A field experiment was conducted for determining the optimum economic B rate (OEBR), critical soil test, and tissue B values for yield and quality response of grapevine to B fertilizer application method (foliar and soil) at 5 doses (0, 1, 3, 9, and 12 kg B/ha) for 2 years. OEBR of foliar and soil application ranged from 6.4 to 8.5 kg B/ha with an average yield of 20.2-12.8 t/ha, respectively. The average soil B content at the OEBR was 0.32-2.52 mg/kg. Leaf tissue B content amounted to 98.9 and 64.4 mg/kg, and berry B content amounted to 21.4 and 12.9 mg/kg for foliar and soil application methods, respectively. Independently of application method, B application increased tissue N, Ca, Mg, P, K, and Zn, yet decreased Fe, Mn, and Cu content. We concluded that a B addition of 6.4 kg/ha for foliar application and 8.5 kg/ha for soil application is sufficient to elevate soil B to nondeficient levels.