Spectra obtained from fresh grapevine organs provide information on chemical composition but could also contain valuable information on the morphological and physical attributes. The prediction of grapevine organs physical attributes using infrared spectroscopy is explored for the first time in this study. Near infrared spectroscopy (NIR) using a solid probe (NIR-SP) and a rotating integrating sphere (NIR-RS) and mid infrared (MIR) were used to obtain spectra from fresh and intact grapevine shoots, leaves, and berries. Linear partial least squares (PLS) and non-linear least absolute shrinkage and selection operator (LASSO), and extreme gradient boost (XGBoost) were implemented to predict relevant physical attributes in grapevine organs. NIR-RS using XGBoost showed coefficients of determination in validation (R2val) of 91.01% and root mean square error of prediction (RMSEP) of 0.71 mm (6.80%) for berry diameter. Shoot diameter was predicted at R2val of 62.08% and RMSEP at 0.82 mm (12.75%) using NIR-RS with LASSO regression. Monitoring these attributes throughout the growing season can lead to important viticultural information on grapevine yield, growth, and health.

Current infrared spectroscopy applications in the field of viticulture are moving toward direct in-field measuring techniques. However, limited research is available on quantitative applications using direct measurement of fresh tissue. The few studies conducted have combined the spectral data from various cultivars, growing regions, grapevine organs, and phenological stages during model development. The spectral data from these heterogeneous samples are combined into a single data set and analyzed jointly during quantitative analysis. Combining the spectral information of these diverse samples into a global data set could be an unsuitable approach and could yield less accurate prediction results. Spectral differences among samples could be overlooked during model development and quantitative analysis. The development of specialized calibrations should be considered and could lead to more accurate quantitative analyses. This study explored a model optimization strategy attempting global and specialized calibrations. Global calibrations, containing data from multiple organs, berry phenological, and shoot lignification stages, were compared to specialized calibrations per organ or stage. The global calibration for organs contained data from shoots, leaves, and berries and produced moderately accurate prediction results for nitrogen, carbon, and hydrogen. The specialized calibrations per organ yielded more accurate calibrations with a coefficient of determination in validation (R2val) at 90.65% and a root mean square error of prediction (RMSEP) at 0.32% dry matter (DM) for the berries' carbon calibrations. The leaves and shoots carbon calibrations had R2val and RMSEP at 84.99%, 0.34% DM, and 90.06%, 0.37% DM, respectively. The specialized calibrations for nitrogen and hydrogen showed similar improvements in prediction accuracy per organ. Specialized calibrations per phenological and lignification stage were also explored. Not all stages showed improvement, however, most stages had comparable or improved results for the specialized calibrations compared to the global calibrations containing all phenological or lignification stages. The results indicated that both global and specialized calibrations should be considered during model development to optimize prediction accuracy.

Biostimulants and biofertilisers are considered environmentally friendly alternatives to synthetic fertilisers, plant growth regulators and crop improvement products. Broadly, plant biostimulants are expected to improve nutrient use efficiency, tolerance to abiotic stress, quality traits and availability of nutrients in the soil or rhizosphere. While there has been increasing interest in the use and benefits of seaweed extracts in wine grape cultivation, limited research has been conducted on Ecklonia maxima (EM), a seaweed specie indigenous to South Africa. In this study EM seaweed extract (Kelpak (R)) was applied on Cabernet Sauvignon as a foliar spray in one season at three grapevine phenological stages: one week before flowering (E-L 18), berry set (E-L 27) and at veraison (E-L 35), on irrigated and non-irrigated vines. The effects on grapevine physiology, grape berry and wine metabolites and microbiota (leaf, berry and must) were evaluated. Grapevine physiology was not influenced by the applied treatments. Leaf area was positively influenced by the EM foliar applications which resulted in improved sugars and organic acids accumulation during ripening. Similar trends were observed in phenolics accumulation in the fruit during ripening. There were large differences in the bacterial and fungal communities on the leaf and berry surfaces from pea-size to harvest. Furthermore, Botrytis and Erysiphe grapevine pathogens were decreased in the leaves and berries (from veraison to harvest) with EM applications. Overall, our study suggests that the use of foliar EM products is beneficial in increasing grape and wine metabolites and the symbiotic microbiota during the ripening period and to ensure sustainable viticulture. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Climate change imposes numerous threats to viticulture. Different strategies have been developed to mitigate these effects that range from innovative vineyard management methods and precision viticulture to the breeding of new varieties and rootstocks better adapted to environmental challenges. Epigenetics refer to heritable changes in genome functioning that are not mediated by DNA sequence variations. The recent discovery that epigenetic memories can mediate acclimation and adaptation of plants to their environment now provides new levers for plant improvement facing climate changes without significant impact on the genetic information. This can be mediated either by using the epigenetic memories of stresses and/ or by creating epigenetic diversity in the form of new epialleles without changing the genetic information. Indeed, grapevine is a perennial grafted clonally propagated plant, and as such, presents epigenetic specificities. These specificities require adapting strategies that have already been developed in model plants but also offer opportunities to explore how epigenetic memories and diversity can be a major source of rapid adaptation to the environment for plants bearing similar properties. Among these strategies, both annual and trans-annual plant priming with different types of elicitors might provide efficient ways to better face (a)biotic stresses. The use of epigenetic exchanges between scion and rootstocks and/or the creation of non-targeted epigenetic variations at a genome-wide scale, or targeted using epigenetic editing, may provide innovative and promising avenues for grapevine improvement to face challenges imposed by climate changes.

Infrared spectroscopy is widely used in viticulture. Spectroscopy correlates spectral properties with reference data to obtain calibrations later used to predict the analyte content in new samples with a single spectral measurement. However, the main limitation lies in generating the reference data required to build robust prediction calibrations. This study proposes a data generation strategy to obtain reference data for larger spectral datasets. A reduced sample set was used to develop initial calibrations. These initial calibrations were subsequently applied to predict the reference data in larger spectral datasets. Calibrations for nitrogen, carbon, and hydrogen content were then attempted using the larger generated datasets. The initial nitrogen calibrations per organ showed coefficients of determination in validation (R2val) between 80.08 and 89.93%. The root mean square errors of prediction (RMSEP) ranged from 0.10 to 0.18% dry matter, and the residual predictive deviations in validation (RPD) were between 2.27 and 3.19. The larger predicted datasets showed improved prediction accuracy with coefficients of determination in validation values above 91.79%, root mean square errors of prediction below 0.14% dry matter, and residual predictive deviations in validation above 3.49. The carbon calibrations showed, on average, a 20% increase in the coefficient of determination in validation decreased root mean square errors of prediction and increased residual predictive deviations in validation. The hydrogen calibrations showed a similar increase in prediction accuracy. The results showed the suitability of using reduced sample sets to generate the reference data of larger datasets capable of yielding more accurate prediction calibrations.

Globally, 7.4 million hectares of arable land is planted with grapevine with a farm gate value of $68.3 billion. The production of grapes faces growing pressure associated with challenges such as climate change, diminishing resources as well as the overuse of chemical fertilizers and synthetic pesticides, which have an impact on sustainability. Consequently, viticulture has over the years embraced and implemented various practices such integrated pest management, organic and biodynamic farming to curb the high chemical inputs typically used in conventional farming. Biostimulants and biofertilizers are considered environmentally friendly and cost-effective alternatives to synthetic fertilizers and plant growth regulators. Seaweed is of particular interest because of its availability globally. It was reported that brown seaweed (Ascophyllum spp.) improves plant growth and agricultural productivity, hormonal signalling, and an improved secondary plant metabolism. It also provides an alternative to soil supplementation, avoiding some of the negative effects of fertilizers through the leaching of nutrients into groundwater sources. This review aims to provide a summary of the use of seaweed extracts in grape production and their influence on grapevine physiology and stress adaptation mechanisms.

Infrared spectroscopy provides extensive spectral and chemical information for plant material. However, the raw spectral data of fresh grapevine organs are poorly understood. This study investigated the spectral properties of grapevine shoots, leaves, and berries collected throughout the growing season. Near infrared (NIR) spectral analysis was performed using a solid probe (NIR-SP) and a rotating integrating sphere (NIR-RS) on samples collected from multiple cultivars and vintages from commercial growing sites at various phenological stages. Clustering patterns of the spectral properties were investigated using principal component analysis (PCA), and unsupervised self-organising maps (SOM) as a novel approach. Separation based on grapevine organ type was seen using both PCA and unsupervised SOM. Thereafter, unsupervised SOM analysis showed organ-specific differences between phenological stages (berries and shoots) and lignification (shoots). Supervised SOM was performed for classification purposes as a novel application on viticultural data for the prediction of grapevine organ and accurate prediction of organ type at 90.3% was observed for the NIR-SP dataset collected from 2019 to 2021. The prediction of individual phenological stages proved more challenging, but when phenological stages were grouped together, a prediction of 85.6% for the NIR-RS grape berry dataset was found. The prediction of shoot lignification yielded accurate results of 74.4% and 89.9% for the NIR-SP 2019-2021 and NIR-RS 2020-2021 datasets, respectively. Furthermore, spectral variable selection with orthogonal partial least squares discriminant analysis (OPLS-DA) and S-plots improved the discrimination of shoots and leaves up to 14% for the NIR-RS 2020-2021 dataset. Lignification predictions also improved by 9.8% for the NIR-SP shoot 2019-2021 (92.3%) and 12.7% for the NIR-RS shoot 2020-2021 (95.9%) datasets. Clustering methods, especially unsupervised SOM, showed important groupings in the raw spectral data for fresh grapevine organs. Organ type, phenological stage, and lignification were highlighted for showing prominent separation over multiple vintages.

The fourth agricultural revolution is leading us into a time of using data science as a tool to implement precision viticulture. Infrared spectroscopy provides the means for rapid and large-scale data collection to achieve this goal. The non-invasive applications of infrared spectroscopy in grapevines are still in its infancy, but recent studies have reported its feasibility. This review examines near infrared and mid infrared spectroscopy for the qualitative and quantitative investigation of intact grapevine organs. Qualitative applications, with the focus on using spectral data for categorization purposes, is discussed. The quantitative applications discussed in this review focuses on the methods associated with carbohydrates, nitrogen, and amino acids, using both invasive and non-invasive means of sample measurement. Few studies have investigated the use of infrared spectroscopy for the direct measurement of intact, fresh, and unfrozen grapevine organs such as berries or leaves, and these studies are examined in depth. The chemometric procedures associated with qualitative and quantitative infrared techniques are discussed, followed by the critical evaluation of the future prospects that could be expected in the field.

The fourth agricultural revolution is leading us into a time of using data science as a tool to implement precision viticulture. Infrared spectroscopy provides the means for rapid and large-scale data collection to achieve this goal. The non-invasive applications of infrared spectroscopy in grapevines are still in its infancy, but recent studies have reported its feasibility. This review examines near infrared and mid infrared spectroscopy for the qualitative and quantitative investigation of intact grapevine organs. Qualitative applications, with the focus on using spectral data for categorization purposes, is discussed. The quantitative applications discussed in this review focuses on the methods associated with carbohydrates, nitrogen, and amino acids, using both invasive and non-invasive means of sample measurement. Few studies have investigated the use of infrared spectroscopy for the direct measurement of intact, fresh, and unfrozen grapevine organs such as berries or leaves, and these studies are examined in depth. The chemometric procedures associated with qualitative and quantitative infrared techniques are discussed, followed by the critical evaluation of the future prospects that could be expected in the field.</p>

Conventional agriculture has made the search for sustainability urgent, more so with regards to climate change. This has extended to the grape and wine industry, an important industry in South Africa in terms of labor employment and foreign exchange. This paper aims to review the current state of knowledge with regards to the three pillars of sustainability and with regards to climate change. In order to understand sustainability in South Africa, a historical context is needed, because the welfare of farm workers still retains vestiges of past Apartheid. Ecological responsibility and higher profits are the main reasons for sustainable practices. Additionally, water use, chemical use, and soil erosion are important environmental sustainability concerns. With regards to climate change, in terms of economic sustainability, there will be winners and losers and social sustainability issues will intensify as changes occur in farms. Table grape producers are relatively more profitable than wine grape producers. Furthermore, pest, disease, irrigation pressure will worsen as the climate warms. However, there are long- and short-term adaptation strategies such as changes in viticulture practices and grape cultivars, respectively, to stem the effects of climate change, but this may be stymied by cost and farmers’ perceptions of climate change.

The stage at which grapes are harvested has an influence on the aromatic and phenolic composition of the berries and the resulting wines. The aim of this study was to evaluate wines harvested sequentially as outlined in the berry sugar accumulation model. Two vintages and treatments in which the light quality and quantity were altered at the fruit zone were compared. In 2010/2011, the grapes were harvested at two ripening stages after the sugar loading plateau was reached, namely the “fresh fruit” stage (20-25 days afterwards) and “pre-mature” stage (at approximately 35 days). In the 2011/2012 season, grapes were harvested 45 days after the sugar loading plateau was reached (the “mature fruit” stage). Vegetative aromas were synonymous with the “fresh fruit” stage in 2010/2011, while the 2011/2012 wines from the “mature fruit” harvest date were characterized by raisin, prune and spicy aromas. In both seasons, the control treatments were rated more intense in ‘satin in the mouth’ in and after expectoration. Wines in which the UV-B radiation was excluded during berry growth were rated the highest in the mouthfeel attribute ‘coarseness’ in both treatment seasons. Wines were analyzed chemically for phenolic content using HPLC, and sensorial using descriptive analysis with a trained panel. In the leaf removal treatments, higher acidity content enhanced the perception of astringency in the wine. Wines were analyzed chemically for phenolic content using HPLC and sensorial using descriptive analysis with a trained panel. Overall, the data showed that grape composition was altered by varying light quality, within a season, but seasonal variation overrode treatment effects. Flavonol concentration in 2011/2012 wine was higher in the exposed leaf removal treatment compared to the other treatments. High light intensities in 2011/2012 season increased anthocyanin concentration in the wine.. This study emphasizes the importance of the quality and quantity of light on the composition and quality of wines, and presents new findings regarding sensory attributes associated with harvesting at different ripening stages.

The evolution of flavonoids under altered temperature and light conditions in the fruit zone was followed in Cabernet Sauvignon (Vitis vinifera L.) grapes during ripening. The study was conducted over two consecutive seasons in 2010/2011 and 2011/2012 comprising two main treatments in which the light quantity was manipulated in the bunch zone: (1) standard (STD) with no lateral shoot or leaf removal and (2) leaf removal west (LRW) treatment with leaf removal on the western side of the bunch zone. Furthermore, the light quality was altered by installing ultraviolet B-suppression sheets within the bunch zone in both seasons. Tannin evolution was dependent on the prevailing light quality/quantity and temperatures during berry development in a particular season. Grape seed tannin accumulation coincided with seed development and commenced at the early stages of berry development. Seed proanthocyanidin composition was not influenced by the treatments. The largest impact on proanthocyanidin accumulation and structure in the skin was due to seasonal variations highlighting the complex interaction between light quality and/or quantity across the two growing seasons and eventually the complex interaction with temperature. Flavonol accumulation was significantly influenced by the light quality, which is known to be the main abiotic driver of flavonol biosynthesis regulation. Anthocyanin concentration and content were largely dependent on the temperature and light quality in a particular season. Anthocyanin composition was altered by the season rather than the treatment.

Grape berry phenolic compounds are widely described in literature. Phenolics can be divided into two main groups: flavonoids and non-flavonoids, of which the flavonoids are the most important. The two best-known groups of flavonoids are the anthocyanins and condensed tannins (also called proanthocyanidins). Anthocyanins are responsible for the red colour in grapes. The condensed tannins (proanthocyanidins) are responsible for some major wine sensorial properties (astringency, browning, and turbidity) and are involved in the wine ageing processes. This review summarises flavonoid synthesis in the grape berry and the impact of environmental factors on the accumulation rate during ripening of each of the flavonoids. The impact of the accumulated flavonoids in grapes and the resulting impact on the sensorial aspects of the wine are also discussed.