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Fruit dropping represents a concern in many fruit species, including Vitis vinifera L. This research investigated the role of two plant growth regulators (PGRs), naphthaleneacetic acid (NAA) and 1-methylcyclopropene (1-MCP), in mitigating preharvest berry dropping (PHBD) through affecting ethylene (ET) and auxin (AUX) metabolism and interactions, key hormones involved in abscission. The experiment was carried out on cv. Dolcetto, with PGR treatments applied at 43, 53, and 90 days after anthesis (DAA) for NAA and at 56 DAA for 1-MCP. Berry dropping incidence, yield parameters, and transcript levels of genes related to ET and AUX pathways were analyzed, including VIT_212s0059g01380, VIT_211s0016g02380, VIT_207s0005g00820, VIT_216s0013g00980, VIT_203s0091g00310, and VIT_207s0104g00800. Both NAA and 1-MCP significantly reduced PHBD, with NAA achieving a 92% reduction and 1-MCP an 82% reduction compared to control vines. Transcript analysis revealed differential gene expression patterns, indicating that NAA affects the ET biosynthesis pathway, while 1-MCP interferes with ET receptor signaling. The results suggest that both PGRs effectively reduced berry dropping, providing a basis for integrated crop management strategies to mitigate PHBD in grapevine cultivars susceptible to this physiological disorder. [ABSTRACT FROM AUTHOR]

This research aimed to identify the effects of increased temperature and decreased ultraviolet (UV) exposure on berry characteristics and quality parameters of cv Nebbiolo, identifying the potential risks associated with climate change for the quality of grapes and the identity of Barolo wine. This two-year research (2022 and 2023) was performed in three vineyards, located at different elevations in La Morra (Piedmont, northwestern Italy), monitored from the beginning of veraison to harvest. A split-plot design was set up, applying a passive greenhouse amplifying temperature in the bunch zone ('T' = increased temperature; 'C' = control temperature) and UV-blocking plastics over individual bunches ('1' = full UV exposure; '0' = UV-blocked). Berry weight, skin weight, and juice total soluble solids were measured. Grape skin anthocyanins, flavonols, and hydroxycinnamic acid tartaric esters were analyzed by HPLC-DAD. Both treatments negatively influenced the berry weight but not the skin weight; the increased T had a negative impact on the sugar per berry content. Limited UV and increased temperature negatively impacted total anthocyanins at harvest and on di-hydroxylated anthocyanins. Limited UV-depressed flavonol concentration and high temperature decreased their synthesis. Increased UV promoted cis-p-coumaroyl tartaric acid and decreased trans-p-coumaroyl tartaric acid. The results of this research are valuable for improving the quality production of Nebbiolo through understanding the impacts of increased temperature and alterations to UV exposure expected by climate change. [ABSTRACT FROM AUTHOR]

The first serious outbreak of Flavescence dorée (FD) in Piedmont (North-West Italy) dates back to 1998 in the Tortona area (Alessandria province). FD is a serious quarantine-worthy disease transmitted by the leafhopper Scaphoideus titanus Ball. Different Vitis vinifera L. biotypes react differently to the phytoplasma, in particular as to the accumulation of polyphenols in leaves. In this experimentation, we observed and described concentration and accumulation of the main classes of polyphenols in entire leaves and in leaf blades and veins of two varieties, Nebbiolo and Barbera, displaying different levels of susceptibility to FD. Their well-known different reactions could be related, at least partially, to leaf polyphenols, both as to concentrations and profiles. Nebbiolo displayed some specific traits: i) the higher percentage of incidence over totals of individual molecules known to be powerful antioxidants (caftaric acid over coutaric acid; quercetin glycosides over other flavonols); ii) the higher concentration of flavanols in veins with respect to Barbera and their wider profile (astilbin and a taxifolin-glycoside, this last accumulating exclusively in Nebbiolo).

The rise of unpredictable, heavy rainfalls increases incidence of diseases, berry rot, berry cracking, and enhance the need for rain shelters. The influence of the type of rain shelter on microclimate and grape quality is still little explored. The aim of this trial was to investigate the radiometric properties of a new type of cover, its effect on vineyard microclimate and on table grape quality, as compared with a reference cover, during a vintage with unusually abundant precipitation for Southern Italy. The new cover was characterized by lower transmissivity to IRshort radiation, and by a very higher transmissivity to UV radiation. It showed a tendency to decrease air temperature by 1 °C, increase RH by 2–3%, reduce VPD, and improve vine water status with respect to the reference. At harvest, grapes covered with the new sheet had higher TSS concentration, TSS / TA ratio, total skin polyphenol and flavonoids content, and berry skin resistance to rupture. Those berries, moreover, increased the level of volatile compounds such as linalool, typical of ‘Italia’ muscat aroma, and terpineol.

The Italian grape germplasm is characterized by a high level of richness in terms of varieties number, with nearly 600 wine grape varieties listed in the Italian National Register of Grapevine Varieties and with a plethora of autochthonous grapes. In the present study an extended SNP genotyping has been carried out on Italian germplasm of cultivated Vitis vinifera subsp. sativa and Vitis hybrids. Several hundred Italian varieties maintained in the repositories of scientific Institutions and about one thousand additional varieties derived from previous studies on European, Southern Italy, Magna Graecia and Georgian germplasm were considered. The large genotyping data obtained were used to check the presence of homonyms and synonyms, determine parental relationships, and identify the main ancestors of traditional Italian cultivars and closely-related accessions. The parentage among a set of 1,232 unique varieties has been assessed. A total of 92 new parent-offspring (PO) pairs and 14 new PO trios were identified. The resulted parentage network suggested that the traditional Italian grapevine germplasm originates largely from a few central varieties geographically distributed into several areas of genetic influence: "Strinto porcino" and its offspring "Sangiovese", "Mantonico bianco" and "Aglianico" mainly as founder varieties of South-Western Italy (IT-SW); Italian Adriatic Coast (IT-AC); and Central Italy with most varieties being offsprings of "Visparola", "Garganega" and "Bombino bianco"; "Termarina (Sciaccarello)" "Orsolina" and "Uva Tosca" as the main varieties of North-Western Italy (IT-NW) and Central Italy. The pedigree reconstruction by full-sib and second-degree relationships highlighted the key role of some cultivars, and, in particular, the centrality of "Visparola" in the origin of Italian germplasm appeared clear. An hypothetical migration of this variety within the Italian Peninsula from South to North along the eastern side, as well as of "Sangiovese" from South to Central Italy along the Western side might be supposed. Moreover, it was also highlighted that, among the main founders of muscat varieties, "Moscato bianco" and "Zibibbo (Muscat of Alexandria)" have spread over the whole Italy, with a high contribution by the former to germplasm of the North-Western of the peninsula. [ABSTRACT FROM AUTHOR]