Effects of cane-and spur-retained node numbers on the pre-flowering vegetative growth of cane-pruned Sauvignon blanc

In established vineyards, node number retention at winter pruning is the first step to achieving and maintaining vine balance. Balanced vines exhibit timely and quasi-uniform 100 percent budburst. To understand how vine capacity and balance are expressed before flowering, mature Sauvignon blanc vines were pruned according to a 5 [total node numbers on canes: 10, 20, 30, 40, 50] x 3 [total node numbers on spurs: 1, 2, 3] factorial design in one site, and in two other sites according to a 5 [total node numbers on canes: 10, 20, 30, 40, 50] x 2 [total node numbers on spurs: 1, 2] factorial design. Two spurs of one, two or three nodes each were retained on either side of the vine. The number of canes laid down per vine was one, two, three and four canes each of 10 nodes for the 10-, 20-, 30-and 40-node treatments, and four canes averaging 12.5 nodes for the 50-node treatment. The budburst percentage was calculated on the whole vine, canes, and spurs. Blind nodes, count shoots, non-count shoots and double shoots were counted and mapped along canes and spurs. Many non-count shoots were measured on the vine head of 10-node vines (29.5 ± 3.0 shoots, p < 0.001), compared to 50-node vines (2.8 ± 1.9 shoots, p < 0.001). 50-node vines had an overall budburst of 100 %, despite having the highest number of blind nodes (7.6 ± 0.3 nodes, p < 0.001). These were mainly located at the canes’ proximal sections relative to the vine head and were likely caused by correlative inhibition and primary bud necrosis. Cane budburst provided a more accurate assessment of the vine response to node loading than vine budburst. The number of double shoots was not associated with the vine node load, as they appeared on both low-node and high-node vines. Three-node spurs developed more blind nodes than one-node and two-node spurs (p < 0.001). Based on the findings of this research, we recommend a composite metric (cane percent budburst, cane blind node count and head shoot count) to assess vine capacity and balance between budburst and flowering, and the practice of retaining one-or two-node spurs at cane pruning is also justified

Bunch microclimate influence amino acids and phenolic profiles of Pinot noir grape berries

IntroductionThe increase of temperature due to climate change at different phenological stages of grapevine has already been demonstrated to affect accumulation of primary and secondary metabolites in grape berries. This has a significant implication for Pinot noir especially in New Zealand context as these compounds can have direct and indirect effects on wine quality. MethodsThis study investigates how varying bunch microclimate through changes in temperature applied at veraison stage can affect: fresh weight, total soluble solids, the accumulation of anthocyanins, total phenolics and amino acids of the grape berries. This was studied over two growing seasons (2018/19 and 2019/20) with Pinot noir vines being grown at two different temperatures in controlled environment (CE) chambers. The vines were exposed to 800 µmol/m2/s irradiance with diurnal changes in day (22°C or 30°C) and night (15°C) temperatures. This experimental set up enabled us to determine the accumulation of these metabolite at harvest (both seasons) and throughout berry development (second season). Results and discussionThe results showed that berry weight was not influenced by temperature increase. The total soluble solids (TSS) were significantly increased at 30°C, however, this was not at the expense of berry weight (i.e., water loss). Anthocyanin content was reduced at higher temperature in the first season but there was no change in phenolic content in response to temperature treatments in either season. The concentrations of total amino acids at harvest increased in response to the higher temperature in the second season only. In addition, in the time course analysis of the second season, the accumulation of amino acids was increased at mid-ripening and ripening stage with the increased temperature. Significant qualitative changes in amino acid composition specifically the α-ketoglutarate family (i.e., glutamine, arginine, and proline) were found between the two temperatures. SignificanceThis study is the first to provide detailed analysis and quantification of individual amino acids and phenolics in Pinot noir in response to changes in temperature applied at veraison which could aid to develop adaptation strategies for viticulture in the future

Investigation of an early harvest regime and pre-fermentative blending treatments to produce lower alcohol wines: impact on grape and wine composition and quality

Warmer and shorter grape ripening periods, as well as concomitant extreme weather events like heatwaves, have been posing considerable challenges for wine producers, particularly when winemakers seek to extend fruit hang-times to meet consumer demands of fuller flavoured wines. Consequently, grapes may not be harvested at desired qualities and may be exposed to over-ripeness or berry shrivel, which likely translate into excessive wine alcohol concentrations. As the nature of these weather events is rather unpredictable and succumbs to annual fluctuations, winemakers rely on flexible and economic strategies (e.g. alternative to current physical dealcoholisation techniques) to ameliorate situations of excessive grape ripeness. Among the various methods to manage wine alcohol levels, one recently proposed strategy is the pre-fermentative dilution of sugar in juice with either a very low alcohol wine (~5 % alcohol by volume) or water. However, the effect of such manipulations on wine compositional and sensory qualities was not entirely understood. Further, it has been unclear how the resulting wines would compare to those of similar alcohol levels made from earlier harvested grapes that are picked to avoid grape over-maturity. For this purpose, studies were undertaken to evaluate these approaches to alcohol management for the production of Cabernet Sauvignon and Shiraz wines under a variety of vintage conditions. The studies have been drafted as manuscripts that have been prepared for publication or have already been submitted or published in peer-reviewed journals. The manuscripts are presented in chapters as outlined below after an introductory chapter. The first study reports on the initial vintage (2015), in which extremely warm and dry conditions caused an exemplary over-maturity of the Cabernet Sauvignon grapes. Experimental wines of various lower alcohol concentrations were produced via prefermentative substitution of juice with a very low alcohol green harvest wine (GHW) or ii water at various rates. The consequences for non-volatile wine composition (colour parameters, tannin and polysaccharide composition) of these pre-fermentative approaches were reported relative to the high alcohol control wine. The characteristics of the substituted wines were discussed in the context of wines of similar alcohol content produced from earlier harvested grapes, thereby providing an evaluation of the role of harvest decision in this extreme vintage scenario. It was shown that colour and tannin parameters were not significantly affected even by the highest substitution rates (with GHW and water) compared to the control and in fact retained values superior to those in wines resulting from earlier harvests. A manuscript detailing this work has been published in Food Chemistry, 244 (2018) 50-59. Further building on the 2015 experimental winemaking, a second manuscript presents the consequences of the alcohol management treatments on wine volatile composition (qualitative and quantitative data obtained with GC-MS analysis) and wine sensory profiles (determined with descriptive sensory analysis). Analysing the same wines as before, the substitution treatments were contrasted with wines arising from earlier harvests to outline potential merits and disadvantages of each approach, this time in terms of volatile and sensory profiles. According to the GC-MS data, the implementation of water had the least effect on the volatile composition, causing rather minor concentration changes of a small fraction of the analysed volatiles. This was further mirrored in the sensory profiles of the lower alcohol wines, which were found to be strongly reminiscent of the overripe control wine, hence there not only positive results (aroma intensity, red fruit, dark fruit) but also negative attributes (hotness) sustained when adjusting the wine alcohol levels via the proposed pre-fermentative treatments. This indicated that wine styles are more affected by harvest date than the substitution treatments. This study has been published in Food Chemistry 259 (2018) 196-206. iii The two studies reporting on the 2015 winemaking trial provided evidence that prefermentative additions of GHW or water are suitable for the production of lower alcohol wines from highly mature Cabernet Sauvignon grapes without greatly affecting the wine quality. The objective of the subsequent study in 2016 was to confirm these findings and to further evaluate an early harvest regime and pre-fermentative substitution treatments as means to produce lower alcohol wines under milder vintage conditions and with relevance to changes in regulation allowing water addition under certain circumstances. Cabernet Sauvignon and Shiraz were investigated and the resulting wines were examined for colour, tannin parameters, volatile composition and sensory properties. The benign nature of the substitution treatments on wine quality parameters, for instance stable levels of anthocyanin and tannin concentrations, was confirmed for Cabernet Sauvignon, but less so in case of Shiraz, where more pronounced differences emerged according to the blending component used. In this case, water substitution was identified as the more suitable treatment to manage wine alcohol levels under mild vintage conditions while preserving the wine quality as defined by harvest date. Wine volatile profiles were generally more affected by the blending treatments in the 2016 vintage context and as a function of the variety. Different responses for Cabernet Sauvignon and Shiraz were associated with the different blending components, however without largely influencing the volatile profiles in comparison to the controls. This study was prepared as a manuscript for submission to a peer-reviewed journal. Following a recent change in regulation that allows the addition of water into the winemaking process (and consequently lowering the wine alcohol concentrations), there has been a particular interest by the wine industry to understand the consequences on wine composition, wine style and quality to facilitate decision making around this newly available winemaking technique. In this context, the final study of experimental Shiraz wines from 2017 extended upon the conclusions drawn in the preceding studies and addressed additional gaps in knowledge about adding water during winemaking. The experiments focused on iv evaluating two options for pre-fermentative water addition during the winemaking process – that is, substitution versus addition without juice removal (i.e., dilution). In addition, the importance of grape maturity on producing high quality, lower alcohol wines with prefermentative water addition was assessed using grapes harvested at two distinct maturity levels, targeting “fresh” and “mature” stages of fruit development. Based on a lower grape maturity (i.e., Fresh Fruit), low juice substitution with water did not change colour properties, whereas the analogous dilution treatment with water elicited declines in colour intensity and stability in line with decreases in total phenolics and tannin concentrations. The juice dilution further resulted in declines of important sensory attributes, such as ‘flavour intensity’ and ‘body’, diverging from the more benign substitution treatments. When applied at a greater grape maturity level (i.e., Mature Fruit), substitution or dilution with water appeared to have a greater effect on colour properties with only small implementation volumes, but high dilution rates in particular resulted in dramatically decreased tannin concentrations. In terms of wine sensory profiles, the differences between substitution and dilution treatments appeared to be less pronounced for Mature Fruit Shiraz wines compared to the Fresh Fruit counterparts, but high implementation rates well beyond the legal limit of must dilution (minimum of 13.5 °Bé) led a noticeable decline in an array of sensory attributes. Analysis of the volatile data is underway and the study will be reported in form of a manuscript for submission to peer-reviewed journal. In conclusion, this work has provided knowledge on the consequences for wine quality associated with pre-fermentative alcohol management approaches involving the implementation of water or a very low alcohol wine into the must. The managed wines were hereby around 1% - 6% lower in alcohol by volume, so generally exceeding the capabilities of other viticultural or microbiologic strategies, but lying within the possibilities of postfermentative physical dealcoholisation technologies. Although observed implications on final wine sensory attributes were marginal particularly at low to moderate levels of alcohol v adjustment, this study has illustrated that higher grape maturities with subsequent alcohol management provides only limited merits to the wine quality, so that an earlier harvest could be a more appropriate solution. Given that this project included three distinct vintage situations and two important red wine varieties, the results can help support winemakers to make informed decisions regarding wine alcohol management according to harvest situation and preferred wine style.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 201

Fifty shades of green – the need to redefine best practice viticulture

Enhancing biodiversity in vineyards is increasingly being recognised as a means of remedying some of the ongoing challenges facing more conventionally-managed properties, such as pest and disease outbreaks. Biodiversity-based strategies are commonly referred to as ‘green infrastructure’. Olaf Schelezki, Wendy McWilliam and Anna-Kate Goodall, from New Zealand’s Lincoln University, outline some of the issues and opportunities around these strategies, particularly from a New Zealand perspective, ahead of an Australasian symposium on the topic of ‘greening vineyards’ this year

Digging a little deeper: Using potted vines to explore the role of roots in vine balance in Pinot noir

The root of our problem is that, by trying to optimise the yield-quality seesaw and understand vine balance, we often forget to go below ground. Potted vine systems are a model system that presents the opportunity to explore these challenges. Since this trial has confirmed that we can successfully increase the size of competing sinks (roots), which leads to changes in our vine balance (overall increased vegetative growth, but no increase in yield) in this model system, we can now extend the investigation to explore potential effects on the grape composition in response to changing the yield­-quality seesaw. This will allow us to better understand the limitations of tilting the yield-quality seesaw at different vineyard conditions in practice while maintaining a sustainable vine balance

Evaluation of an Incentive Programme for Increasing Green Infrastructure on Vineyards

Wine grape ecosystems with low species richness and reliance on agrichemicals have weak resilience to environmental impacts. Increasing biodiversity through green infrastructure (GI) not only helps mitigate some of these impacts but can provide additional benefits to growers and the public. Despite this, many vineyards have limited GI. While scholars suggest incentive programmes may help to encourage GI implementation, few studies have evaluated their effectiveness. We surveyed winegrowers and their vineyards in the Waipara Valley sub-region, New Zealand, to evaluate an incentive programme aimed at increasing GI on vineyards, particularly indigenous vegetation. The results indicated the programme was effective in encouraging growers to plant indigenous plants in areas incapable or unsuitable for growing grapes, largely in support of nature conservation, aesthetics, branding, and sales. It was less successful in encouraging growers to plant them in productive areas. While substantial GI, primarily in the form of inter-row cover crops, was managed in these areas, most were exotic plants seen by growers to provide superior services (especially erosion control, weed suppression and pest regulation) at lower management complexity and cost. Growers identified six GI enablers: (1) promoting GI types that provide greater grower services than disservices and costs of implementation and management; (2) implementing GI where biophysical conditions support success; (3) providing assistance with plant selection and design; (4) providing GI implementation and/or management funding; (5) developing GI certification policies and regional association programmes; and (6) providing government GI regulations, strategies, and incentives. They also identified five barriers: (1) insufficient grower appreciation for indigenous GI services; (2) grower concerns that some GI disservices were greater than their services; (3) grower belief that costs of GI implementation and/or management were greater than those of alternative practices; (4) harsh and remote GI growing conditions; (5) lack of grower knowledge regarding how to design plantings, especially those that could provide multiple services; and (6) lack of sufficient financial resources for GI implementation and/or management. Twenty recommendations for improving GI implementation are provided

Comparison of consecutive harvests versus blending treatments to produce lower alcohol wines from Cabernet Sauvignon grapes: Impact on wine volatile composition and sensory properties

Available online 27 March 2018Abstract not availableOlaf J. Schelezki, Katja Šuklje, Paul K. Boss, David W. Jeffer

Potted vines: Exploring the management effect of leaf area to fruit weight ratios on yield and quality

The concept of vine balance is attaining a functional equilibrium between the three essential grapevine sinks — fruit, shoots, and roots. This means that any manipulation of source-sink balance that alters competing sinks will influence the equilibrium of the plant. The leaf area to fruit weight ratio (LA:FW) is a key metric used for assessing balance between the vegetative and reproductive growth of the vine. This ratio indicates that the main source of carbohydrates supplied to the fruit derives from leaf photosynthesis. A leaf area of 0.8-1.5m² of leaf/kg of fruit is reported to be optimal in the field. An alternative measure is that to ripen a bunch a shoot requires 14 leaves. Thus, vines that are source limited (inadequate leaf area) or have a high yield and excessive sink demand, will potentially have inadequate carbohydrates to enable fruit to reach an optimum ripening. The outcome of this imbalance is grapes can be low in soluble solids concentration, lighter colour, and undeveloped flavours and aroma at harvest. Therefore, it is essential to define the right balance between the vegetative and productive relationship to increase yield as well as improving the biochemical composition of the grape, ultimately affecting the yield-quality seesaw

Characterizing retained dormant shoot attributes to support automated cane pruning on Vitis Vinifera L. cv. Sauvignon Blanc

Background and Aims: The shortage of skilled pruners portends automation as an alternative. To train an Artificial Intelligence (AI) system in cane pruning, the attributes of grapevine dormant shoots were characterised. Methods and Results: Eight attributes of dormant shoots, diameter, length, vertical and horizontal distance, node number, internode length, origin and position relative to bottom fruiting wire, were measured prior to and after pruning. Vine canopies were modified according to a 5 [total node numbers on canes: 10, 20, 30, 40, 50] × 3 [total node numbers on spurs: 1, 2, 3] factorial design. Compared to non-retained dormant shoots, retained dormant shoots were thicker (9.2 ± 0.07 mm), longer (104.7 ± 0.93 cm), close to the vine trunk (11.4 ± 0.65 cm) and below the bottom fruiting wire (83.2 ± 0.54 cm). Spurs had the shortest horizontal (9.8 ± 0.93 cm) and vertical (77.8 ± 0.7 cm) distance, originating from the vine head, base nodes and first nodes of old canes and old spurs. Modifying the vine canopy via increased node numbers had a significant effect on all retained dormant shoot attributes (P < 0.05) except on the position relative to the bottom fruiting wire. Conclusions: Cane pruning in commercial vineyards is consistent and follows rules based on viticulture knowledge. Retained, non-retained dormant shoots, canes and spurs exhibit distinct attributes useful in quantifying, assessing and modelling cane pruning. Significance of the Study: Data and knowledge from the research are currently being used in modelling and training AI cane-pruning algorithms