Background and Aims
Earlier ripening of grapes due to global warming could be mitigated by delaying hand pruning on pre‐pruned canes. Hand pruning on pre‐pruned vines was delayed until after distal ...buds on canes had burst for Sangiovese (Vitis vinifera L.) vines, and the effect on phenology, canopy development, leaf gas exchange, yield and berry development and composition was assessed.
Methods and Results
Pre‐pruned vines, which were subsequently hand‐pruned during winter, were compared to vines where hand pruning was delayed (DP) until shoots from distal nodes of canes had burst and developed 3–4 (DP3) or 7–8 (DP7) expanded leaves. Delayed pruning delayed budburst by about 30 days in DP3 vines and 37–47 days in DP7 vines, which led to a slowing of canopy development and berry growth. Veraison was delayed by between 10 and 20 days. Yield was substantially reduced by delaying hand pruning but the concentration of phenolic substances and the acidity of berries was increased.
Conclusions
Delaying hand pruning on vines that had already been pre‐pruned delayed budburst, anthesis and veraison, reduced yield and significantly affected berry composition. The magnitude of these effects increased with the length of the pruning delay.
Significance of the Study
Delaying hand pruning on pre‐pruned grapevines may represent a promising technique to mitigate against some of the deleterious effects of global warming in vineyards.
Background and Aims
The effect of global warming on grape ripening has led to the development of strategies for delaying sugar accumulation. This study evaluated the effectiveness of the application ...of the film‐forming anti‐transpirant di‐1‐p‐menthene on the berry ripening of Sangiovese grapevines with different crop loads.
Methods and Results
Over 2 years, the vines with high (H) or medium (M) crop load (leaving about one bunch for every two shoots) were sprayed (T) or not (C) with the anti‐transpirant film‐forming spray post‐veraison (as assessed by a colour change). The di‐1‐p‐menthene treatment inhibited leaf photosynthesis during bunch ripening for about 30 days, limiting berry sugar accumulation. Yield per vine was related to TSS, with di‐1‐p‐menthene‐treated vines showing the greatest effects. Increments of 1 kg of yield corresponded to a reduction of about 0.67°Brix in the Control vines and of 0.79°Brix in the treated vines.
Conclusions
The temporary reduction of photosynthesis reduced berry TSS. In high crop‐load vines, the application of di‐1‐p‐menthene delayed TSS accumulation more than the high crop load.
Significance of the Study
The anti‐transpirant applied during post‐veraison delayed the accumulation of sugar in berries more than the high crop load.
BACKGROUND AND AIMS: Accelerated berry sugar accumulation resulting in wines of excessive alcohol concentration, subâoptimal colour and atypical flavour has become increasingly frequent in warm ...growing districts, a trend induced by factors that include global warming. The application of a filmâforming antitranspirant may be an effective way of reducing early sugar accumulation without affecting colour development. METHODS AND RESULTS: An antitranspirant emulsion was applied in 2013 and in 2014 on fieldâgrown cv. Barbera vines at preâflowering (PF), preâveraison (PV) and at both dates (PFPV), and compared with the unsprayed control. Postâtreatment assessment included seasonal gas exchange, yield components, growth of berry organs and must composition. Although all treatments were effective in reducing gas exchange by as much as 46% compared with that of the control, berry growth was not affected. Conversely, whereas PF slightly modified the ripening pattern, PV and PFPV markedly delayed accumulation of sugar in the warm 2013 season (â2.4 and â3.7° Brix, respectively, vs control) without detriment to colour development because the onset of anthocyanins occurred at lower TSS. In the cooler, wet 2014 season, PV and PFPV were again able to delay sugar accumulation without affecting colour development. CONCLUSIONS: Preâveraison application of the antitranspirant alone or in combination with a PF spray proved effective in slowing sugar accumulation while avoiding concurrent delay of colour development. SIGNIFICANCE OF THE STUDY: The use of antitranspirants is a practical and flexible way of regulating the sugarâ:âanthocyanin ratio under conditions of excessively fast ripening.
Background and Aims
Higher temperature during the season is forcing growers in Central Italy to explore ways to reliably control vine yield and grape ripening, while maintaining grape composition. ...The most common approaches include altering winter pruning, shoot thinning (St), leaf removal and bunch thinning. These studies, however, rarely evaluated these practices in concert and over multiple seasons.
Methods and Results
From 2009 to 2013, five treatments were applied to Vitis vinifera L. cv. Montepulciano: winter pruning only (Wp, Control); Wp plus St; St plus pre‐flowering defoliation (St + Dpa); St plus pre‐veraison defoliation (St + Dpv); and St + Dpv plus bunch thinning (St + Dpv + Bt) applied prior to veraison. Effects on canopy architecture, yield, ripening and berry composition were measured. Compared to Wp, St, St + Dpv and St + Dpv + Bt treatments reduced leaf area and leaf layer number in the fruiting zone, while St + Dpv + Bt reduced yield. No treatment slowed ripening. The treatment St + Dpa reduced yield and the incidence of Botrytis cinerea, and improved fruit composition, but increased TSS in berries. All treatments were ceased after 2013 and the vines were pruned in winter only. The treatment St + Dpa imposed in 2013 had a strong carry‐over effect on yield but not TSS in 2014.
Conclusions
Shoot thinning alone reduced canopy density but failed to reduce yield or improve fruit composition. Both the St + Dpv and St + Dpv + Ct treatments provided a more open fruit zone, had no effect on yield and increased TSS in fruit at harvest. Shoot thinning plus pre‐flowering defoliation decreased yield and improved berry composition in a Mediterranean climate; however, given its observed carry‐over effects on yield this approach should be applied only in alternate years, suggesting the need for further research exploring additional viticultural practices.
Significance of the Study
Despite some benefits of St, defoliation and bunch thinning on their own or even in concert, no combination tested was consistently effective for controlling vine yield and grape ripening, while maintaining grape composition.
Background and Aims
Global warming is inducing a general earliness in the onset of grapevine phenological stages including ripening, a phenomenon that occurs often in the hottest seasons and which ...leads to unbalanced wines. Our aim was to assess the physiological basis of late leaf removal applied above the bunch area as a tool for delaying ripening.
Methods and Results
Potted cv. Sangiovese grapevines were subjected to leaf removal treatments applied preveraison (DEF‐I) and postveraison (DEF‐II) by pulling out six to seven primary leaves and laterals, if any, above the bunch zone; untouched vines served as the control. Whole‐canopy net CO2 gas exchange was monitored seasonally from 9 days before DEF‐I to 35 days after DEF‐II. Concurrently, single‐leaf gas exchange was assessed, and at harvest yield components, grape composition and the leaf‐to‐fruit ratio were determined. The seasonal carbon/yield ratio did not differ between treatments because of the high capacity for photosynthetic compensation shown by the DEF treatments and quantified as about a 35% higher net CO2 gas exchange per unit of leaf area per day. While ripening was temporarily retarded in both DEF treatments, with sugar content being lower and titratable acidity higher, a week later both treatments had fully or partially recovered; phenolic ripening was unaffected at either harvest date.
Conclusions
Defoliation above the bunch zone applied at lag‐phase and postveraison (average 12°Brix) was effective in temporarily delaying technological ripeness without affecting colour and phenolics. This result depended upon the high compensation capacity for photosynthesis shown by vines in both treatments.
Significance of the Study
The data provide a preliminary yet robust physiological background for targeting better field application of the technique.
Background and Aims
Postveraison limitation of canopy photosynthesis delays grape berry ripening and reduces sugar accumulation, thus lowering the alcohol content of the subsequent wines. This study ...was designed to evaluate whether similar results could be obtained by defoliation apical to the bunch zone using a leaf‐plucking machine when berry sugar content was approximately 16–17°Brix.
Methods and Results
In 2011 and 2012, defoliation treatments were applied postveraison to cv. Sangiovese vines (D) on either side of each row using a mechanical leaf remover, and these D vines were compared to a nondefoliated control (C). The machine removed 35% of the leaves on the vine and created a 50‐cm vertical window without leaves above the bunch area, but retained a few leaves at the canopy apex (about 0.50 m2/vine). In both years, leaf removal reduced the rate of berry sugar accumulation and led to a 1.2 lower harvest °Brix and consequently, a lower wine alcohol (−0.6%) content in D relative to that of C vines. In 2012, sugar content of D vines, monitored in a group of vines that was not harvested, had recovered to that of C vines 2 weeks after harvest. The concentration of total phenolic compounds in the grapes, the chemical and chromatic characteristics of the wines and the replenishment of soluble sugars, starch and total nitrogen in the canes and roots were similar in the D and C vines.
Conclusion
To achieve an effective delay in sugar accumulation in the berries, leaves should be removed at 16–17°Brix, and at least 30–35% of vine leaf area should be removed.
Significance of the Study
Mechanical removal of leaves postveraison above the bunch zone of Sangiovese can be an easy and economically viable technique for delaying sugar accumulation in the berries and for limiting the alcohol content of wines with no negative impact on desirable composition of either berries or wines.
Malate is accumulated in grape pericarp until the start of ripening and then it is dissimilated. One aim of this study was to determine if the potential contribution of stored malate to the substrate ...requirements of metabolism in ripening grape pericarp is dependent on the cultivar. Two Vitis vinifera L. cultivars which accumulated different amounts of malate and had ripening periods of a different length were compared. The potential contribution of stored malate over the whole period of ripening was around 20 % in the cv. Sagrantino and 29 % in the cv. Pinot Noir. The contribution was higher in Pinot Noir because it contained more malate and had a shorter ripening period. A second aim of this study was to evaluate the contribution of gluconeogenesis to the amount of sugar accumulated in the pericarp. If all the dissimilated malate was utilized by gluconeogenesis, then the maximum contribution of stored malate to the total amount of sugar accumulated in the pericarp over the whole period of ripening was around 2.4 % in Sagrantino and 2.9 % in Pinot Noir. However, the actual contribution was only about 0.1–0.6 % in both cultivars because the majority of stored malate was not utilized by gluconeogenesis. However, it is likely that the actual contribution is much lower. This suggests that the function of gluconeogenesis is not to support accumulation of sugars in the fruits, but probably it plays other roles.
Testing of new rootstocks for drought tolerance targets traditionally rain-fed districts where supplemental irrigation is more frequently needed due to the pressures of global warming. A seasonal ...evaluation of gas exchange and water-use efficiency (WUE) of cv. Sangiovese grafted to the new drought-tolerant genotype M4 in a dry-down trial against the commercial SO4 stock is reported. The experiment was conducted in 2014 on twelve 2-year-old, non-fruiting potted Sangiovese grapevines grafted on M4 and SO4 stocks and assigned to SO4-WW (well-watered), SO4-WS (water-stressed), M4-WW and M4-WS treatments. Progressive water deficit was imposed by reducing water supply to 70, 50 and 30 % of whole-canopy demand derived from concurrent measurements of transpiration in WW. Unlike SO4, M4 showed slower stress progression, as highlighted by pre-dawn leaf water potential, and retained higher whole-canopy net CO
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exchange rates (NCER) and transpiration rates per unit of leaf area at all replenishment levels as well as exhibiting higher canopy WUE at both 50 and 30 % WW. Although single-leaf assessment was in partial disagreement with data recorded on the whole-canopy basis, robust data were acquired to confirm that the M4 stock performs better than SO4 at any water replenishment level in terms of higher NCER/leaf area and/or canopy WUE. Findings feed expectations that grafting Sangiovese to the M4 rootstock should result in a problem-solving tool for rain-fed areas subject to temporary summer drought.
Ripe berries often results too rich in sugar in recent years, though harvest is done in advance, thus the hypothesis of limiting berry sugar accumulation by lowering canopy carbon assimilation during ...ripening phase was tested in 2011 season. Post-veraison removal of the most functional leaves on the upper part of the canopy of vertical shoot positioned medium-vigour ‘Sangiovese’ and ‘Montepulciano’ grapevines was performed mechanically in a hillside vineyard established in 2006 nearby Ancona, Central Italy. Grapevines, 2.75x1.2 m spaced, were cordon trained and spur pruned. The tractor-mounted Plucker leaf stripper (Tanesini Technology, Faenza, Italy) operated on both side of the canopy on August 26, 2011 (i.e. 28 days after veraison and 34 days before harvest), when berry sugar concentration was already at 22°Brix and total acidity was still around 9-10 g/L. The leaf stripper removed from the upper part of the canopy (0.7-1.0 m above the cordon) 60 and 29% of the leaf area in ‘Sangiovese’ and ‘Montepulciano’ respectively. As a consequence, total leaf area per vine lowered by 25% in ‘Sangiovese’ and 14% in ‘Montepulciano’. Leaf/fruit ratio at harvest lowered from 1.18 to 0.73 m2/kg in ‘Sangiovese’ and from 1.23 to 1.03 m2/kg in ‘Montepulciano’. The significant reduction of total leaf area registered in post-veraison defoliated grapevines of both cultivars did not affect yield per vine, bunch and berry weight, total acidity and pH of the must, but lowered juice soluble solids concentration (-0.7°Brix in comparison to control in both cultivars). Post-veraison defoliation negatively affected anthocyanins and polyphenols concentration at harvest in ‘Montepulciano’ grapevines, but not in ‘Sangiovese’ ones. Thus mechanical leaf removal, quick and easy to perform late in the season to obtain grapes less rich in sugar, may be detrimental to berry colour according to genotype and should be carefully tested on black-berried cultivars before large scale application.
Background and Aims: Total leaf area and its distribution inside the canopy are known to influence the photosynthesis capacity as well as grape quality and health. The aim of this work was to ...evaluate the effectiveness of a simple and innovative training system characterised by an open canopy called ‘SAYM’ (a closing Y‐shaped training system derived from the spur‐pruned single cordon and trained to an inclined shoot‐positioned trellis type) as well as the possibility of using traditional machines during harvesting and pruning after closing the structure just before grape harvesting.
Methods and Results: The SAYM was applied on eight rows of 80 vines from an experimental Sangiovese vineyard and compared to vertically shoot‐positioned (VSP) trellis type during the 2004–2008 seasons. In comparison to VSP vines, the SAYM was able to reduce the incidence of botrytis rot and improve grape and wine quality (alcohol, anthocyanins, phenolics, tannins and colour intensity), while maintaining an adequate yield (about 13 t/ha) without significantly increasing the management operations of the vineyard.
Conclusions: The SAYM was able to bring together economically and easily the advantages guaranteed by training systems characterised by horizontally divided canopy with the limitation of production costs by the use of traditional mechanical harvesters and pruners.
Significance of the Study: SAYM can be proposed as a functional training system able to improve grape and wine quality, which is easy and inexpensive to manage.
