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Abstract Background Weed control is essential for agricultural floor management in vineyards and the inter-row mulching is an eco-friendly practice to inhibit weed growth via filtering out photosynthetically active radiation. Besides weed suppression, inter-row mulching can influence grapevine growth and the accumulation of metabolites in grape berries. However, the complex interaction of multiple factors in the field challenges the understanding of molecular mechanisms on the regulated metabolites. In the current study, black geotextile inter-row mulch (M) was applied for two vintages (2016–2017) from anthesis to harvest. Metabolomics and transcriptomics analysis were conducted in two vintages, aiming to provide insights into metabolic and molecular responses of Cabernet Sauvignon grapes to M in a semi-arid climate. Results Upregulation of genes related to photosynthesis and heat shock proteins confirmed that M weakened the total light exposure and grapes suffered heat stress, resulting in lower sugar-acid ratio at harvest. Key genes responsible for enhancements in phenylalanine, glutamine, ornithine, arginine, and C6 alcohol concentrations, and the downward trend in ε-viniferin, anthocyanins, flavonols, terpenes, and norisoprenoids in M grapes were identified. In addition, several modules significantly correlated with the metabolic biomarkers through weighted correlation network analysis, and the potential key transcription factors regulating the above metabolites including VviGATA11, VviHSFA6B, and VviWRKY03 were also identified. Conclusion This study provides a valuable overview of metabolic and transcriptomic responses of M grapes in semi-arid climates, which could facilitate understanding the complex regulatory network of metabolites in response to microclimate changes.

Adding pomace or juice runoff during maceration is a traditional winemaking process. To mitigate the negative effects of rainfall during harvest and examine the effects of adjusting the pomace ratio during fermentation on the flavor profile of Marselan grape wines, the prefermentation addition of Petit Manseng grape pomace (PAP) and prefermentation juice runoff (PJR) was determined. The phenolic and volatile compounds were investigated using HPLC–MS and GC–MS. PAP enriched the flavanols and PJR enriched the pigment and copigment matrix. Approximate 10% increase in the ratio of pomace promoted the formation of anthocyanin derivatives. The increased pomace ratio reduced the concentration of volatile compounds without impacting the aroma quality. Sensory analysis revealed PAP wines scored higher for acidity and astringency and PJR wines scored higher for color. In conclusion, an appropriate increase in the pomace ratio of approximately 10% can enhance the color and mouthfeel of the wine while having a limited influence on aroma.

Recently, revealing the terroir influence on wine chemical features has drawn increasing interest. This study aimed to explain how wine flavonoid signatures were altered by vineyard parcel, harvest ripeness, vintage and bottle aging. Six commercial Cabernet Sauvignon vineyards were selected in the Manas region to produce wines at three harvest ripeness in three seasons (2019–2021) and aged for three years. The six vineyards had little difference in mesoclimate conditions while varying greatly in soil composition. Results showed high vineyard pH (> 8.5) could accelerate grape ripening rate and increase wine flavonol concentration. Vineyards with moderate nutrition produced wines with abundant anthocyanin derivatives and maintained color characteristics during aging. The role of detailed anthocyanin derivatives in regulating wine color was clarified. As the harvest ripeness elevated, wine’s flavonoid profiles were altered and gained a higher red color intensity. This work provides chemical mechanisms underlying single-vineyard wines and a theoretical basis for targeted wine production.

The heterogeneity of the vineyard environment caused high variability in grape metabolites and flavor profiles, and the phenomenon was more prominent in recent years of climate change. Herein, distal leaf removal was applied in semi-arid Xinjiang to adjust the source to sink ratio of grapevines for three consecutive years (2018–2020). The grape-derived volatiles showed high correlations with specific climate factors such as temperature changes in the growth period. Results showed that distal leaf removal increased the solar radiation reaching the clusters in the first few days after applying LR treatments while not affecting the temperature. The improvement in fruity and floral aroma intensity by distal leaf removal was founded not only in grape metabolites but also in wines. Moderate cluster exposure brought by distal leaf removal was beneficial for the accumulation of isoprenoids, which therefore increased the fruity and floral intensity of wines. The carry-over effect did not show in consecutively defoliated vines among vintages regarding the wine aroma profile.

Rootstocks are commonly utilized owing to their resistance to abiotic and biotic stress in viticulture. This study evaluated the effects of three rootstocks (1103P, SO4, and 5A) on the Cabernet Sauvignon (CS) vine growth, and their berries and wines flavonoids profiles in four consecutive vintages. The results showed that 1103P increased the pruning weight of CS and decreased the anthocyanin concentration in berries and wines, especially in the vintages with more rainy and cloudy days. 5A tended to decrease the pruning weight of CS and increase the anthocyanin concentration in berries and wines. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the concentrations of total anthocyanins, F3’H-anthocyanins, malvidin-3-O-glucoside (Mv-glu), and malvidin-3-O-acetylglucoside (Mv-acglu) were the key substances affected by the rootstocks in CS berries and were significantly decreased by 1103P. Total anthocyanins, pinotins, Mv-glu, epicatechin, and vitisins were the rootstock-sensitive compounds that commonly differed in wines among the three comparison groups in the two vintages. Furthermore, 1103P brought more brightness to the wine and 5A gave the wine more red tones. In conclusion, rootstock 5A was recommended in the rainy and cloudy climate regions with regard to the berry flavonoids accumulation and the wine color.

The double cropping system has been widely applied in many subtropical viticultural regions. In the 2-year study of 2014–2015, four grape varieties were selected to analyze their fruit volatile compounds in four consecutive seasons in the Guangxi region of South China, which had a typical subtropical humid monsoon climate. Results showed that berries of winter seasons had higher concentrations of terpenes, norisoprenoids, and C6/C9 compounds in “Riesling,” “Victoria,” and “Muscat Hamburg” grapes in both of the two vintages. However, in the “Cabernet Sauvignon” grapes, only the berries of the 2014 winter season had higher terpene concentrations, but lower norisoprenoid concentrations than those of the corresponding summer season. The Pearson correlation analysis showed the high temperature was the main climate factor that affected volatile compounds between the summer and winter seasons. Hexanal, γ-terpinene, terpinen-4-ol, cis-furan linalool oxide, and trans-pyran linalool oxide were all negatively correlated with the high-temperature hours in all of the four varieties. Transcriptome analysis showed that the upregulated VviDXSs, VviPSYs, and VviCCDs expressions might contribute to the accumulations of terpenes or norisoprenoids in the winter berries of these varieties. Our results provided insights into how climate parameters affected grape volatiles under the double cropping system, which might improve the understanding of the grape berries in response to the climate changes accompanied by extreme weather conditions in the future.

Canopy shading is a widely used viticultural strategy for mitigating early grape berry ripening caused by global warming. In this study, we covered half of the canopy with a black shade cloth from the pea-size stage to harvest. In the fruit zone, canopy shade treatment (ST) reduced daily average solar radiation by about 74.6 % compared to the untreated control (UC), and significantly reduced daily average temperature. ST leaves were found to have lower net assimilation rates and higher internal CO2 concentration than in UC, which resulted in reduced yield, bunch weight, cane starch and berry total soluble solids. A delayed development stage was found in ST berries which had lower pH and higher titratable acid than UC. ST increased both berry and wine anthocyanin concentration while significantly decreasing flavonol concentration. ST wines had higher concentrations of a number of ester compounds and β-damascenone than UC wines, thus significantly enhancing the floral and fruity aroma of ST wines. Higher C6/C9 and fatty acids concentrations in ST berries may have caused higher ester concentrations in ST wines. The results showed significant effects on metabolites in berries and wines caused by canopy shade.

Covering crops was a commonly used viticultural technique to adjust the vineyard microclimate, thus affecting the grape and wine quality. In this two-year study, the purslane (Portulaca oleracea L.) was used to cover the lands between rows in the vineyards located in the semi-arid Northwest China, Xinjiang. Results showed that the photosynthetically active radiation around the fruit zone and the temperature with the purslane covering treatment decreased. Compared with the clean tillage, covering purslane had lower TSS and higher TA in the grape berries, while lower alcohol content and higher TA was also found in their corresponding wines. Covering purslane treatment significantly increased the contents of anthocyanin and flavonol in the grapes and wines in the year 2018, but no significant effect on flavanols was observed in the wines. Norisoprenoids, esters, and C6 alcohols in the grapes and wines were increased in the purslane covering treatment, respectively. Additionally, compared to the clean tillage, the purslane covering treatment significantly improved the sensory value of the wines, especially the floral aroma and the complexity of the wines. This study helped us to better understand the feasibility of applying covering purslane in viticulture in the semi-arid climate of Northwest China.

Under the double cropping system, berries usually showed significant quality variations in the summer and winter seasons. In the two-year/four-consecutive-season study, two table grapes of ‘Muscat Hamburg’ and ‘Victoria’ were investigated to determine the phenolic compounds in their berries. Different from those of the summer season, the berries in the winter season suffered no high-temperature stress since veraison to harvest in 2014 and 2015. The variations in the season temperatures led to a higher anthocyanin concentration in the winter season berries of ‘Muscat Hamburg’ grapes than that in the summer berries, while the summer season berries had higher proportions of acylated and methylated anthocyanins than those in the winter season berries. Similar to the anthocyanins, the winter season berries also had a higher flavonol concentration in both varieties. Transcriptome analysis showed that the upregulated genes involved in the flavonoid pathway in the winter season berries were agreed with the changes found in the metabolites. However, the influence of the growing seasons on the flavanols was not consistent in the two varieties, and the variations in VviLARs between the grapes of ‘Muscat Hamburg’ and ‘Victoria’ might be the cause. This research helped us better understand the double cropping system and how the climate factors affected the phenolic compounds in the double cropping system.

A new method for synthesis and characterization of the first pentanuclear extended metal atom chains (EMACs) of the second-row transition metals, [[Ru.sub.5][([[mu].sub.5]-tpda).sub.4][X.sub.2]] where ([tpda.sup.2-] = tripyridyldiamido dianion, X = Cl and NCS) is reported. The detailed studies provide insight into the spectroscopic, magnetic properties, electrochemical redox states, and electrical conductance.

The article describes the synthesis of the first second-row metal extended metal atom chains, [Ru5(µ5-tripyridyldiamido)4X2]. According to the authors, the chemistry of ruthenium enables its applications in electron and energy transfer. They add the key to the success of the synthesis was the addition of an excess amount of LiCl, prior to metalation, to reflux with the starting materials, H2dpa and Ru2(OAc)4Cl.