Use of Metabolic Profiling To Study Grape Skin Polyphenol Behavior as a Result of Canopy Microclimate Manipulation in a ‘Pinot noir’ Vineyard

Abstract

Canopy microclimate manipulation can have a significant effect on grapevine gene expression and can thus affect the yield of many important berry compounds. Focusing on only a few targeted phenolics in the past, advanced multimethod analytical approaches are opening up much wider possibilities to fill in the gaps of missing knowledge about plant secondary metabolism. Different leaf removal timings, leading to different microclimate scenarios, were thus introduced in a 'Pinot noir' vineyard to reveal related alterations of multiple classes of skin phenolics, including some rarely studied to date. Different accumulation trends during cluster development were detected not only between groups but also between individual compounds within groups. Although many significant changes were observed early in the season, these were later often less significant. However, at harvest, 31 of 72 detected compounds showed significant differences in comparison to control for at least one of three leaf removal approaches.

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

“…The relative abundance of di-and triand OH-and OCH 3 -substituted anthocyanins was unaffected by leaf removal when applied before flowering (Table 3), in contrast to previous studies. 14,15 As for tannin content, our data support the results of previous studies indicating that viticultural practices have a limited effect on skin and seed tannin content. 14,22,35 Both leaf-removal treatments affected the concentration of MPs during berry development; at harvest, significantly lower values were measured in LRAF berries ( Table 2).…”

“…14,15 As for tannin content, our data support the results of previous studies indicating that viticultural practices have a limited effect on skin and seed tannin content. 14,22,35 Both leaf-removal treatments affected the concentration of MPs during berry development; at harvest, significantly lower values were measured in LRAF berries ( Table 2). The MP concentration in the berry can be affected by multiple factors, specifically light and temperature, 2,9,36−39 crop level, 40 vigor, and high leaf area-to-yield ratio.…”

“…4,11 Moreover this technique can improve grape composition 4,12 by increasing total soluble solids (TSS), 4,11,13 anthocyanins, and other polyphenols; 4,11,14 possibly by improving the leaf area-to-yield ratio. However, this results have not always been consistent between climates, vintages, and cultivars.…”

Influence of cluster zone leaf removal on Pinot noir grape chemical and volatile composition

“…The concentration of quercetin glycosides increased with increasing cluster exposure and increasing PAR during all 3 years of the study. Others have shown increased quercetin glycosides with cluster exposure (Price et al, 1995;Spayd et al, 2002;Sternad Lemut, Sivilotti, Franceschi, Wehrens, & Vrhovsek, 2013). Quercetin glycosides have been associated with anthocyanin polymerisation in wine and can enhance wine colour stability and quality (Price et al, 1995).…”

Leaf removal at veraison stage differentially affects qualitative attributes and bioactive composition of fresh and dehydrated grapes of two indigenous Cypriot cultivars

“…Leaf removal is a common preharvest canopy management practice used in viticulture to modify the cluster zone microclimate, thus enhancing grape ripening, reducing the incidence of diseases, and facilitating pesticide penetration into the canopy. The main objectives of leaf removal are the increase of grape exposure to sunlight and the subsequent elevation of berry temperature, which are both factors that directly affect the metabolism of grapes and consequently their composition and quality . However, the alteration of grape composition by leaf removal might also rely on factors other than microclimate, namely, changes in leaf‐to‐yield ratio, assimilation rates of the remaining leaves, changes in source‐sink balance, berry size, and consequently the skin‐to‐pulp ratio…”