Early defoliation in a temperate warm and semi-arid Tempranillo vineyard: vine performance and grape composition

Abstract

Background and Aims Early defoliation (ED) can reduce vine yield and improve fruit composition in vigorous vineyards. The objective of this study was to test the effectiveness of this technique for the Vitis vinifera (L.) cultivar Tempranillo under the temperate warm and semi‐arid climatic conditions of south‐eastern Spain. Methods and Results Four treatments were applied over three seasons to drip‐irrigated vines, planted with rows orientated north–south and shoots vertically positioned. Non‐defoliated vines (control) were compared with vines defoliated either just before anthesis (phenological stage H, treatment ED) or at fruitset [phenological stage J, treatment late defoliation (LD)]. In the fourth treatment, only the leaves facing east were removed at phenological stage H (treatment east ED). In the fourth experimental season, all treatments were managed similarly. Defoliation did not reduce fruitset but reduced berry mass, particularly in the ED and the LD treatments. Defoliation, however, had a cumulative negative effect on vine bud fertility. Even in the fourth experimental season, the yield of the ED treatment was 18% lower than that of the control. Both the ED and particularly the LD treatments increased berry total soluble solids (TSS) and phenolic concentration. The effect of leaf removal on berry TSS and phenolic concentration was not significant in the east ED treatment. Conclusions Defoliation at fruitset was the most effective treatment for increasing berry phenolics and TSS while maintaining must acidity. Growers should take into account, however, the important yield penalty because of defoliation, particularly in the mid‐term. Significance of the Study Early defoliation of Tempranillo grapes growing in semi‐arid and temperate climates needs to be applied with caution and probably limited to specific seasons while consecutive defoliations should be avoided.

Impact of Leaf Removal, Applied Before and After Flowering, on Anthocyanin, Tannin, and Methoxypyrazine Concentrations in ‘Merlot’ (Vitis vinifera L.) Grapes and Wines

“…15,16 Similar to TSS, the impact of leaf removal before or after flowering on TA is still controversial. Experiments carried out on 'Pinot noir', 'Trebbiano', 'Merlot' (V. vinifera L.), 'Cabernet Sauvignon', and 'Sangiovese' reported no impact of this technique on TA, 15,28,29 while an increase of TA was shown under leaf removal before flowering in 'Sangiovese' and in 'Tempranillo'.…”

“…However, this results have not always been consistent between climates, vintages, and cultivars. 15,16 Despite the fact that this strategy has been suggested for high-yielding varieties, the reduction of crop size might help improve the composition of red grapes even in vineyards where leaf area-to-yield ratios are above limiting thresholds (0.8 m 2 /kg), 17 but crop size reduction via, for example, cluster thinning is normally applied by grape growers to improve grape composition. Indeed, there is a lack of information on how the reduction of crop size and the increase in leaf area-to-yield ratio can affect the accumulation of secondary metabolites and particularly volatiles such as methoxypyrazines.…”

Agronomic performance of 'Cabernet Sauvignon' with leaf removal management in a high-altitude region of Southern Brazil

“…In this sense, defoliation has been an important canopy management to improve the quantity and quality of the phenolic compounds of berries (Moreno et al, 2014), and the timing of leaf removal is another key factor in the accumulation of phenolic compounds (Gatti et al, 2012). In previous studies, Moreno et al (2014) also observed that leaf removal resulted in greater accumulation of phenolic compounds, whereas Tardaguila et al (2010) and Risco et al (2014) found that early leaf removal caused an increase in polyphenol content. It has been suggested that the biosynthesis of polyphenols is light dependent, favoring their accumulation (Sun et al, 2012).…”

“…Early leaf removal, associated with a high incidence of solar radiation, provides a reduction in total acidity contents, due to the degradation of malic acid Risco et al, 2014). This effect may also be a result of the direct exposure of clusters to the sun, which increases their temperature and, consequently, the rate of cellular respiration, causing malic acid degradation (Conde et al, 2007).…”

Timing of leaf removal modifies chemical and phenolic composition of Sauvignon Blanc wine

“…At both harvests, leaf removal carried out until berries pepper-corn size phenological stages resulted wines with the lowest values of total acidity, while wines from plants without leaf removal show the highest total titratable acidity. Early leaf removal associated with high solar radiation provides a reduction in berries acidity due to the greater degradation of malic acid [24,25]. For pH of the wine, it was observed that earlier leaf removal, before véraison, showed elevation of pH ( Table 1).…”