Photoselective Shade Films Mitigate Heat Wave Damage by Reducing Anthocyanin and Flavonol Degradation in Grapevine (Vitis vinifera L.) Berries

Abstract

Wine grape production is challenged by forecasted increases in air temperature and droughts due to climate change and photoselective overhead shade films are promising tools in hot viticulture areas to overcome climate change related factors. The aim of this study was to evaluate the vulnerability of ‘Cabernet Sauvignon’ grape berries to solar radiation overexposure, optimize shade film use for preserving berry composition. An experiment was conducted for two years with four shade films (D1, D3, D4, D5) with differing solar radiation spectra transmittance and compared to an uncovered control (C0). Integrals for leaf gas exchange and mid-day stem water potential were unaffected by the shade films in both years. At harvest, berry primary metabolites were not affected by treatments applied in either year. Despite precipitation exclusion during the dormant seasons in shaded treatments, and cluster zone temperatures reaching 58°C in C0, yield was not affected. Berry skin anthocyanin and flavonol composition and content were measured by C18 reversed-phase HPLC. In 2020, total skin anthocyanins (mg·berry-1) in the shaded treatments were 27% greater than C0 during berry ripening and at harvest. Conversely, flavonol content in 2020 decreased in partially shaded grapevines compared to C0. Berry flavonoid content in 2021 increased until harvest while flavonol degradation was apparent from veraison to harvest in 2020 across partially shaded and control grapevines. Untreated control showed lower di- to tri-hydroxylated flavonol ratios closer to harvest. Our results provided evidence that overhead partial shading of vineyards mitigate anthocyanin degradation by reducing cluster zone temperatures and is a useful tool in combatting climate change in hot climate regions.

Overhead photoselective shade films mitigate effects of climate change by arresting flavonoid and aroma composition degradation in wine

“…Briefly, wine samples collected after pressing were centrifuged at 5,000 rpm for 10 mins, filtered with PTFE membrane filters (diameter 13mm, pore size: 45 mm, Overhead shade films installed above the experimental vineyard and the percentage of solar radiation spectra transmitted through them at solar noon. Portion of this figure previously appeared in Marigliano et al (2022).…”

“…The experiment was arranged in a randomized complete block with four replications. The photoselective shade film treatments were previously described in Marigliano et al (2022) and their properties presented in Figure 1. Shade films were designed to target portions of the electromagnetic spectrum previously observed and measured at the experimental site (Martıńez-Lüscher et al, 2017;Martıńez-Lüscher et al, 2019).…”

“…The effect of photoselective overhead shade films on whole plant physiology and temporal development of berry flavonoids of Cabernet Sauvignon development over two growing seasons was previously studied in a hot region (Marigliano et al, 2022). Grape berries growing under reduced near-infrared radiation exposure in hotter than average years, resulted in a 27% increase in anthocyanin content at harvest than the exposed control due to decreases in anthocyanin degradation due to high berry temperatures (Marigliano et al, 2022). Moreover, flavonol degradation was similarly decreased, thus optimizing flavonol content in the grape berry under reduced near-infrared radiation exposure (Marigliano et al, 2022).…”

“…Grape berries growing under reduced near-infrared radiation exposure in hotter than average years, resulted in a 27% increase in anthocyanin content at harvest than the exposed control due to decreases in anthocyanin degradation due to high berry temperatures (Marigliano et al, 2022). Moreover, flavonol degradation was similarly decreased, thus optimizing flavonol content in the grape berry under reduced near-infrared radiation exposure (Marigliano et al, 2022). The objectives of this study aimed to determine the extent to which the impact of photoselective overhead shade films on flavonoid development transfer to wine and the cascading effects of partial solar radiation exclusion had on aroma composition of resultant wines.…”

Not All Light Spectra Were Created Equal: Can We Harvest Light for Optimum Food‐Energy Co‐Generation?

“…The majority of these studies, although sometimes with contrasting results, suggest that some parts of the light spectrum are less efficient in terms of carbon assimilation and water use and could be more effectively used to produce solar energy. Studies under field conditions where photo‐selective shade nets were applied to lettuce (Amaro de Sales et al., 2021), apple trees (Bastías et al., 2021), and grapevine (Marigliano et al., 2022; Martínez‐Lüscher et al., 2017) also suggest that proper sunlight management can lead to improved crop performance, higher water use efficiency (WUE), and mitigation of heat wave damage.…”