Secondary Bud Gas Exchange, Growth, and Fruitfulness of Vitis vinifera L. cultivars, ‘Grenache’ and ‘Cabernet Sauvignon’ Grown on the Texas High Plains

In 2017, the grape and wine industry had an overall economic impact of $13.1 billion within the state of Texas. The majority of grapes grown in Texas are produced within the Texas High Plains American Viticultural Area (AVA). However, vineyards within the Texas High Plains AVA are subject to late spring frosts which can potentially diminish fruit quality, and reduce crop production. To assist in planning and production efforts, Texas High Plains AVA grape growers require information regarding vine secondary bud growth and fruitfulness. Therefore, the objectives of this experiment were to compare the growth and fruitfulness of shoots grown from primary and secondary buds of Vitis vinifera L. ‘Grenache’ and ‘Cabernet Sauvignon’ vines grafted to 110R rootstocks. Vines were planted in an experimental vineyard in 2008. Each year over two consecutive growing seasons (2016 – 2017) vines were exposed to the following treatments: primary bud growth intact, and following bud break allowing primary bud shoot growth to reach 15.0 cm in length then removing primary bud shoots (forcing growth from secondary buds). Gas exchange, growth, fruitfulness, and fruit total soluble solid data were collected each year. Collected data followed similar trends each growing season. Hence, data from each growing season were pooled. Gas exchange data indicate leaves from primary shoots had lower photosynthetic rates, and stomatal conductance when compared to leaves grown on secondary shoots. In addition, ‘Grenache’ leaves had greater gas exchange when compared to ‘Cabernet Sauvignon’ leaves. Pruning weights, vine yield, cluster mass, and total soluble solids were greater for shoots grown from primary buds. ‘Cabernet Sauvignon’ vines had greater pruning weights, but ‘Grenache’ vines had greater crop load (Ravaz Index) and cluster mass. Yield and total soluble solids did not differ between grape cultivars, but the number of clusters from each vine, and berry mass varied with cultivar and bud treatment. In the late spring frost-prone Texas High Plains AVA, cultivar selection continues to be a critical factor for vineyard success. Results indicate decreased yields from all vines with shoot growth only from secondary buds. However, even though ‘Grenache’ and ‘Cabernet Sauvignon’ vines responded differently to bud treatments (‘Cabernet Sauvignon’ vines generally produced a greater number of smaller clusters when compared to ‘Grenache’ vines), for each cultivar overall yield was similar across all bud treatments. Therefore, Texas High Plains AVA and other grape producers now have additional information that may assist them when making critical vineyard management choices.

Impact of training system on ‘Blanc Du Bois’ vegetative growth, yield components and fruit composition

‘Blanc Du Bois’ (Vitis spp.) is the most widely grown Pierce’s disease tolerant white grapevine cultivar in Texas. As an interspecific hybrid, its growth habit is seimi-drooping, and 'Blanc Du Bois' is characterized as vigorous. This study evaluated the impact of training system (Mid-Wire Cordon with VSP, Mid-Wire Cane with VSP and Smart-Dyson, High-Wire Quadralateral, and Watson) on 'Blanc Du Bois' growth, yield components, and fruit composition at two locations in Texas. The first site was located in the Rio Grande Valley where the mean extreme minimum winter temperature is -1.1 to 1.7° C (USDA Cold Hardiness Zone 10a). As a result of climate and site conditions, vine size, determined by dormant pruning weight, was very large averaging from 3.71 to 5.56 kg per vine across training systems over a three-year period. At this site, the horizontally divided systems, High-Wire Quadrilateral and Watson were the highest yielding averaging 10.66 and 7.49 kg per vine, respectively, as a result of more shoots per vine, and higher fruitfulness. The Mid-Wire Cordon and Mid-Wire Cane Pruned Training Systems had lower yields in two out of three years, but fruit maturity indices soluble solids and pH reflected more advanced maturity at harvest. At the second site, located in the Central Gulf Coast of Texas (USDA Cold Hardiness Zone 8b), vines were less vigorous with pruning weights averaging 1.66 to 1.83 kg per vine across training systems over three years. Consistent differences in yield components, vine size, and fruit composition were not observed, and all the three training systems under study had acceptable growth and fruiting characteristics. The results of this research suggest that 'Blanc Du Bois’ vigor potential and growth habit makes it well-suited for horizontally divided canopy training systems, particularly on vigorous sites.

Effect of the plot variability on the qualitative and quantitative characteristics of the berry's skins and seeds of grape cultivar Agiorgitiko (Vitis vinifera L.)

Soil properties, climatic conditions and cultivation techniques constitute significant variables, which affect the quality of the final product. In particular, soil data (soil texture, soil electrical conductivity etc.) and weather data (average temperature, humidity etc.) affect both crop quality data (sugar content, anthocyanins content, phenolic compounds concentrations etc.) and crop quantity data (crop yield, berry weight and size etc.). The aim of this study was to investigate the variations of the microclimatic areas that exist within the same vineyard and their effect on the qualitative and quantitative characteristics of the berry skins and seeds of the grapes. These microclimatic areas could be identified and classified as those which could produce grapes for PDO wines and those which could be used for the production of other types of wines. The overall results of this study indicated important differences between the grapes of different sub-zones from the perspective of their chemical analyses, namely with notable differences identified between the grapes in the anthocyanin concentration and mainly in the concentration of malvidin, acetyl and coumaric esters of malvidin. A significant variability was observed in the characters of the must and in berry mechanical properties. More specifically, higher weight of berries was observed in the lower part of the vineyard, based on its slope. In the north-eastern part of the vineyard, a higher concentration of polyphenolic compounds was recorded. The concentration of total anthocyanins was found to be positively correlated with the soil slope, while significant variability in the concentration of total anthocyanins was revealed.

Opening data and research objects in viticulture: The Viticulture Data Journal (VDJ)

The Viticulture Data Journal (VDJ) is launched with the aim of offering a publication venue for non-conventional but valuable outputs of the research cycle: data, models, methods, software, data analytics pipelines and visualisation methods in viticultural research. VDJ is published on the ARPHA journal platform, which supports the full life cycle of a manuscript, from writing through submission, peer review, publication and dissemination within a single online collaborative platform. During the AGINFRA+ project, which has supported the journal launch, ARPHA has been extended to be used from the AGINFRA+ Virtual Research Environment (VRE).

Comparative study of qualitative and quantitative characters of grape cultivar 'Mavrodafni' (Vitis vinifera L.) and 'Renio' grown in different regions of the Protected Designation of Origin Mavrodafni Patras

'Mavrodafni' (Vitis vinifera L.) is considered one of the oldest grapevine cultivars indigenous to the Greek vineyards, with western Peloponnese being its primary centre of cultivation. 'Renio' is considered to be either a biotype of 'Mavrodafni' or an altogether different cultivar. Both 'Mavrodafni' and 'Renio' can be found in the vineyards of the areas of cultivation, since 'Renio' is considered to be more productive compared to 'Mavrodafni' and, for this reason, it has gradually replaced 'Mavrodafni' from cultivation over the course of time. 'Mavrodafni' and 'Renio' contain appreciable amounts of quality characters of grape and must in terms of total polyphenol and total anthocyanins content in berry skins, depending on the different regions where they are cultivated and they would be worthy of further study and use for the production of different types of wines.