Viticulture in Argentina under extreme weather scenarios:Actual challenges,future perspectives

Viticulture in Argentina is an important socioeconomic sector,reflected in a significant wine market and tourism.However,climate change and related extreme events are serious concerns.The main issues are heatwaves,hail-storms,and heavy rainfall,resulting in damage to vineyards.While climate change impacts have already been discussed for regions such as the Mediterranean,the literature lacks an up-to-date overview of Argentine viticul-ture and potential mitigation solutions.In a country culturally and economically connected to the world of wine,it is strategic to bridge this gap to be prepared for a climatically adverse future.This perspective paper presents an overview of Argentine viticulture and its relationship to climate change.We focus on the Mendoza region,one of the most productive areas and home to cultural landscapes where internationally recognized wines are produced.Climate change is already occurring,a fact we observed by analyzing data from the past decades.We discussed how heatwaves in the lowlands drive farmers to move to the Andes slopes looking for more favorable conditions.But new threats arise,such as extreme rainfall.Due to surface hydrological processes,they can cause land degradation and compromise vineyards.We investigate these phenomena in detail,highlighting how they represent a growing challenge that must be addressed for the sustainable development of future viticulture in the area.Therefore,we propose mitigation strategies for more resilient production,drawing inspiration from the Sustainable Development Goals and suggesting a framework that can be extended to broader contexts worldwide。

The Landscape Analysis of Viticulture and Enology in Georgia

Georgia has been the country of vines and wine since ancient times, and historically vine growing and wine making has performed the function of one of the leading branches of economy. The diverse and rich information about growing vines and producing wine in Georgia can be found in historical and modem scientific literatures as well. Javakhishvili reviewed 413 vine species from the ancient period in his work： ＂Economic History of Georgia＂. Nowadays there are more than 420 species in Georgia or 2.5% of the whole world assortment, from which 27 are for wine, 14 edible and 41 standard species. According to the ecological and economic conditions, Georgia is divided into 11 main regions from the viewpoint of specialization and concentration of vine growing, of which Kakheti, Kartli, Imereti, Racha and Lechkhumi are the most important regions. All these regions are both producers and users of grapes and wine. The climate of Kakheti is favorable to develop the vine industry here. They are： Rkatsiteli, Saperavi, Mtsvane, Kabeme and Khikhvi. Kakheti gives more than half of branded wines of the republic. Fifty-four percent of vineyards of the country are placed, and 65%-68% of total wines in Georgia are produced in Kakheti.

New Scenarios for a Shift towards Agroecology in Viticulture

In the light of its negative impacts on the environment and human health, conventional agriculture is currently facing new challenges;for example, reducing pesticide reliance, improving biodiversity, adapting to climate change and reconciling winegrowers with consumers, which require changes to be made to vineyard management. A shift towards more sustainable agriculture via the development of agroecological systems may be key to meeting these environmental, economic and social challenges. This study aimed to evaluate the performance of existing viticultural systems, as well as that of three new scenarios that we built to change conventional vine production systems and their related practices. The end aim is to adopt the principles of agroecology, and more virtuously, to ensure that vine production remains in line with societal expectations. First, thirty-eight different viticultural systems were chosen. Three realistic scenarios for changing these production systems were then built by working with stakeholders and incorporating the best practices that had been identified in the vineyard. Conventional practices were optimised in the first scenario and an agroecological approach was adopted for the other two scenarios: an Agroecological scenario (using synthetic chemicals) and an Agroecological-Bio scenario (organic system). All three scenarios were based on a combination of good practices which contribute to enhancing vineyard biodiversity, and which thus restore biological regulation and in turn reduce pesticides. The viticultural systems performances have been evaluated with a methodology involving multicriteria decision aid using ELECTRE Tri-C and ELECTRE III methods. Seven evaluation criteria were selected which covered socio-economic performance (economic profitability, workload and system complexity) and environmental performance (pesticide pressure, pesticide ecotoxicity, agroecological practices and pesticide drift). The best performances were achieved by the two agroecological scenarios, and this methodology can be adaptable to different production systems everywhere in different viticultural regions.

Climate Change Favors Grapevine Production in Temperate Zones

Wine production has a long-standing history in Palatinate (Southwestern Germany), dating back to Roman times. Especially “Riesling”, but also several “Pinot” varieties gained major significance. Red wine varieties gained prominence over the last 20 years only, which may be a consequence of climate change. Our objective was to review temperature and rainfall data over the last 40 years, measured “on-winery” in Hainfeld and correlate these data with grapevine growth parameters: the development of bud break, flowering, veraison and harvest dates, yields and grape sugar concentrations of “Pinot Gris”, “Pinot Noir”, “Riesling”, “Silvaner” and “Müller-Thurgau”. Since the 1970s, bud break, flowering and veraison are 11 - 15, 18 - 22 and 16 - 22 days earlier;harvest dates are 25 - 40 days earlier. Sugar concentrations increased significantly, but yields decreased. Annual rainfall has not significantly risen, while the mean annual minimum and maximum air-temperatures rose by ~0.9°C, and by ~3.4°C, respectively, resulting in an average increase of the mean annual temperature of ~2.1°C. Remarkably, both mean monthly minimum and maximum temperatures rose especially in springtime, which should have been the driver for earlier bud break and flowering. A change in the climatic conditions, therefore, appears to be one of the key reasons for more favorable grapevine production in Palatinate, especially for “Pinot Noir”, which showed the highest increase in sugar concentrations. The Huglin-index, a measure for the suitability of growing specific grapevine varieties in given environments, increased from 1685 to 2063. According to this index, the climate change may be favorable already for growing grape varieties so far rarely grown in temperate zones, such as “Cabernet Sauvignon”, “Syrah” and “Tempranillo” that are more suited to warmer, Mediterranean climates.

Performance of interspecific grapevine varieties in north-east Italy

A renewed interest in interspecific varieties has recently emerged, due mainly to producers and consumers more aware of organic farming and impact of phytochemicals in the environment. The assessment of 19 European Vitis hybrids was investigated in an area mostly dedicated to viticulture, the North-EasternItaly. Major agronomic traits, yield, quality characteristics and disease resistance were evaluated during a three-year period (2004 to 2006). Wine sensory analyses were performed and compared with international Vitis vinifera varieties. Even though no genotypes resulted adequate for market release, the results obtained confirm the potential importance of hybrids in an “eco-friendly” viticulture and identify the genotypes interesting for further investigation and breeding: GF 138-3 and GA 48-12 showed good agronomic performance, resistance to more grape diseases and high quality wine.

Evaluation of Some New Wine Grape Cultivars under S^o Francisco Valley Conditions

This study aimed to evaluate the performance and characteristics of the grapes as subsidies to the recommendation of new wine grape cultivars for the S^o Francisco Valley. An experiment was carried out in Petrolina, Pernambuco state, during four seasons in 2014 and 2015 and the treatments were represented by 10 cultivars and three breeding selections： Grenache, Tempranillo, Merlot, Cabernet Sauvignon, Malbec, Petit Verdot and Syrah for red wines and Sauvignon Blanc, Chardonnay, Chenin Blanc and breeding selections 46, 14 and 47 for white wines. The experimental design was a randomized block with four replicates and two useful plants per plot. The following variables were evaluated： sprouting, bud fertility rate, Ravaz index, production, number of clusters, weight, length and width of cluster, weight and volume of 100 berries, soluble solids and titratable acidity. A better balance between production and vigour was obtained in Grenache, Merlot and Tempranillo cultivars, presenting values of 7.56, 6.50 and 5.93, respectively, for Ravaz index. Grenache, Chenin Blanc and Tempranillo were the most productive cultivars with average yields estimated at 10.4, 8.7 and 8.4 ton/ha/season. Selection 14 had longer, wider and less compact clusters, which can reduce clusters rottenness. The percentage of sprouting ranged from 38.13% in selection 14 to 77.6% in cv. Chenin Blanc. The average index of bud fertility was 0.79 cluster/bud, with no significant differences among cultivars. Greater potential for sugar accumulation was found in the selections 14, 46 and 47, while the titratable acidity ranged from 0.63% in cv. Merlot to 0.89% in selection 47. Grenache and Tempranillo have showed potential to obtain adequate yield and balanced vines, while Sauvignon Blanc, Chardonnay, Cabemet Sauvignon, Malbec and Petit Verdot presented low yield being necessary to select clones more productive and well adapted to the tropical conditions. Further information about the quality of grapes and wines should be added to these results to allow the recommendation of new cultivars or breeding selections of wine grapes for the Sao Francisco Valley.

Canopy Management of Table Grapes Cultivar in Tropical Conditions

The production of some seedless table grapes under tropical conditions presents low bud fertility on the main canes and low yield, which leads to the need of pruning in the lateral shoots. The objective of this study was to evaluate the influence of the canopy management for the formation of lateral shoots associated with dellsity of canes on the yield and quality of grapes ＂Sugraone＂ in the Sao Francisco Valley. The experiment was carried out over two growing seasons （2011-2012） in a commercial vineyard of Sugraone in Petrolina, Pernambuco state, Brazil. The treatments consisted of two canopy managements （shoot topping associated to elimination of lateral shoots and shoot topping and formation of lateral shoots） combined with two to three densities of canes after pruning （1.8, 2.8 and 3.8 canes/m^2）. The formation of ＂lateral shoots＂ increased yield and number of clusters per plant during two consecutive growing seasons, besides using 2.8 varas/m^2 resulted in highest yields only in 2011 growing season. The variables mass bunch, mass berry, soluble solids （SS）, soluble sugar, titxatable acidity （TA） and pulp firmness were not affected by treatments, while the attributes related to color, as like brightness and hue angle of the skin, and total extractable polyphenols content were influenced by canopy management, especially in the 2012 growing season. Shoot topping to induce formation of laterals shoots associated with density of 2.8 canes/m2 increased the yield of seedless grapes cultivar Sugraone grown in the Sao Francisco Valley, not significantly affecting the quality of the grape.

Population genomics highlights structural variations in local adaptation to saline coastal environments in woolly grape

Structural variations(SVs)are a feature of plant genomes that has been largely unexplored despite their significant impact on plant phenotypic traits and local adaptation to abiotic and biotic stress.In this study,we employed woolly grape(Vitis retordii),a species native to the tropical and subtropical regions of East Asia with both coastal and inland habitats,as a valuable model for examining the impact of SVs on local adaptation.We assembled a haplotype-resolved chromosomal reference genome for woolly grape,and conducted population genetic analyses based on whole-genome sequencing(WGS)data from coastal and inland populations.The demographic analyses revealed recent bottlenecks in all populations and asymmetric gene flow from the inland to the coastal population.In total,1,035 genes associated with plant adaptive regulation for salt stress,radiation,and environmental adaptation were detected underlying local selection by SVs and SNPs in the coastal population,of which 37.29% and 65.26% were detected by SVs and SNPs,respectively.Candidate genes such as FSD2,RGA1,and AAP8 associated with salt tolerance were found to be highly differentiated and selected during the process of local adaptation to coastal habitats in SV regions.Our study highlights the importance of SVs in local adaptation;candidate genes related to salt stress and climatic adaptation to tropical and subtropical environments are important genomic resources for future breeding programs of grapevine and its rootstocks.

Digital surface model applied to unmanned aerial vehicle based photogrammetry to assess potential biotic or abiotic effects on grapevine canopies

Accurate data acquisition and analysis to obtain crop canopy information are critical steps to understand plant growth dynamics and to assess the potential impacts of biotic or abiotic stresses on plant development.A versatile and easy to use monitoring system will allow researchers and growers to improve the follow-up management strategies within farms once potential problems have been detected.This study reviewed existing remote sensing platforms and relevant information applied to crops and specifically grapevines to equip a simple Unmanned Aerial Vehicle(UAV)using a visible high definition RGB camera.The objective of the proposed Unmanned Aerial System(UAS)was to implement a Digital Surface Model(DSM)in order to obtain accurate information about the affected or missing grapevines that can be attributed to potential biotic or abiotic stress effects.The analysis process started with a three-dimensional(3D)reconstruction from the RGB images collected from grapevines using the UAS and the Structure from Motion(SfM)technique to obtain the DSM applied on a per-plant basis.Then,the DSM was expressed as greyscale images according to the halftone technique to finally extract the information of affected and missing grapevines using computer vision algorithms based on canopy cover measurement and classification.To validate the automated method proposed,each grapevine row was visually inspected within the study area.The inspection was then compared to the digital assessment using the proposed UAS in order to validate calculations of affected and missing grapevines for the whole studied vineyard.Results showed that the percentage of affected and missing grapevines was 9.5%and 7.3%,respectively from the area studied.Therefore,for this specific study,the abiotic stress that affected the experimental vineyard(frost)impacted a total of 16.8%of plants.This study provided a new method for automatically surveying affected or missing grapevines in the field and an evaluation tool for plant growth conditions,which can be implemented for other uses such as canopy management,irrigation scheduling and other precision agricultural applications.