Late trimming delays sugar accumulation in grapes

Background and Aims Climate change can alter the synchronous accumulation of sugar and other main berry compounds during ripening. The aim of this study was to determine whether post-veraison trimming could delay sugar accumulation and influence the production of anthocyanins and seed tannins in Sangiovese grapes. Methods and Results Shoots were trimmed in 2009, 2010 and 2011 when the berry total soluble solids (TSS) reached 15–17°Brix, leaving eight nodes on each main shoot. The accumulation of TSS, anthocyanins and seed tannins was measured during ripening, and yield parameters were recorded at harvest. Grapes from trimmed vines contained a lower TSS in 2009 and 2010, but there was no impact on the concentration of anthocyanins and seed tannins. In 2011, leaf area limitation was insufficient to reduce TSS accumulation, because yield constraints were observed and the leaf area/yield ratio was within the optimal range. Conclusions The lower rate of TSS accumulation in berries had no impact on the concentration of anthocyanins and seed tannins, suggesting that this approach could produce grapes with a lower TSS at harvest or delay harvest. In low-vigour vines suffering from water deficit, the post-veraison trimming repeated over the years could reduce yield, which may be responsible for the lack of TSS reduction compared with that of control vines. Significance of the Study Our study provides insight into the relationship between TSS accumulation and the production of anthocyanins and seed tannins in the berry in response to post-veraison leaf area reduction

Increasing the source/sink ratio in Vitis vinifera (cv Sangiovese) induces extensive transcriptome reprogramming and modifies berry ripening

<p>Abstract</p> <p>Background</p> <p>Cluster thinning is an agronomic practice in which a proportion of berry clusters are removed from the vine to increase the source/sink ratio and improve the quality of the remaining berries. Until now no transcriptomic data have been reported describing the mechanisms that underlie the agronomic and biochemical effects of thinning.</p> <p>Results</p> <p>We profiled the transcriptome of <it>Vitis vinifera </it>cv. Sangiovese berries before and after thinning at veraison using a genome-wide microarray representing all grapevine genes listed in the latest V1 gene prediction. Thinning increased the source/sink ratio from 0.6 to 1.2 m²leaf area per kg of berries and boosted the sugar and anthocyanin content at harvest. Extensive transcriptome remodeling was observed in thinned vines 2 weeks after thinning and at ripening. This included the enhanced modulation of genes that are normally regulated during berry development and the induction of a large set of genes that are not usually expressed.</p> <p>Conclusion</p> <p>Cluster thinning has a profound effect on several important cellular processes and metabolic pathways including carbohydrate metabolism and the synthesis and transport of secondary products. The integrated agronomic, biochemical and transcriptomic data revealed that the positive impact of cluster thinning on final berry composition reflects a much more complex outcome than simply enhancing the normal ripening process.</p

Maturazione accelerata delle uve ed eccessivo grado alcolico del vino. Cosa può fare la ricerca se cambia il clima?

E’ noto che negli ultimi 20 anni si sono verificati importanti cambiamenti climatici, le cui principali manifestazioni hanno riguardato l’aumento delle temperature che ha determinato in molti ambienti viticoli, ed in particolare per le uve rosse, una accelerazione dei processi di accumulo degli zuccheri nelle bacche, con un evidente anticipo temporale del momento in cui il livello glucometrico del mosto risulta ottimale per la raccolta. In tale momento, peraltro mentre non risultano ancora presenti gli aromi tipici dell’uva ed altre fondamentali caratteristiche positive dell’acino (colore della buccia, sintesi dei composti fenolici, imbrunimento dei vinaccioli, perdita di astringenza, ecc.), che genericamente sono indicate con il termine di “maturità fenolica”.Tenuto conto di ciò è possibile chiedersi se vi siano interventi agronomici capaci di contrastare l’accorciamento del periodo di accumulazione zuccherina. Una possibile tecnica potrebbe essere l’utilizzo di tagli meccanici drastici sulle parti medio-alte dei germogli in post-invaiatura per eliminare le foglie più funzionali, ridurre la sintesi dei carboidrati e rallentare il loro trasferimento nelle bacche. Per i medesimi scopi potrebbe essere applicata in post-invaiatura anche la defogliazione meccanica per tutta l’altezza della chioma o di prodotti antitraspiranti

Vitigni e portinnesti ottenuti per incrocio intraspecifico e interspecifico

L'ampio programma di miglioramento genetico messo in atto negli anni '80 e '90 presso l'Universit\ue0 di Bologna, e portato a termine in questi anni ha permesso di selezionare il Merlese (incrocio tra Merlot e Sangiovese) e due accessioni di portinnesti nanizzanti

Potatura del Nebbiolo

Prova di potatura su cv. Nebbiol

Interaction of leaf age, fruiting and exogenous cytokinins in Sangiovese grapevines under non-irrigated conditions. II. Chlorophyll and nitrogen content

The interactions of leaf age, chlorophyll, and nitrogen content, together with modifications induced by fruiting and kinetin application, were investigated in horizontally trained shoots of field-grown Sangiovese (Vitis vinifera L.) grapevines. Dry weight per unit leaf area (W) increased over a leaf age span of five months and showed a curvilinear relationship with Pn rates reported earlier in the companion paper. Regression of chlorophyll per unit leaf area versus leaf age was curvilinear, maximum chlorophyll content being recorded at 80 to 90 days of age. The correlation of chlorophyll versus Pn was not significant within any shoot zones. Leaf nitrogen content plotted against leaf age exhibited different patterns depending on the unit chosen to express the data. An exponential negative regression was found when leaf N was given as percentage of dry weight. By contrast, a cubic regression fit the data when leaf N content was on a leaf-area basis. Nitrogen accumulated in the leaf up to about 45 to 50 days of age, and then an export pattern set in. Correlation of N versus Pn within each shoot zone was significant only for basal mature leaves when nitrogen data were expressed on a dry-weight basis, whereas the data for median leaves were significant when given on a leaf-area basis. Leaf age effects were not modified by crop level or kinetin. These results indicate that caution is needed when trying to use W, chlorophyll, and nitrogen as indicators of photosynthesis capacity for grapevine leaves of varying age

Un'analisi critica dei rapporti tra produzione e qualit\ue0 dell'uva

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I sistemi di allevamento della vite: tradizione e innovazione

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