A renewed interest in interspecific varieties has recently emerged, due mainly to producers and consumers more aware of organic farming and impact of phytochemicals in the environment. The assessment of 19 European Vitis hybrids was investigated in an area mostly dedicated to viticulture, the North-EasternItaly. Major agronomic traits, yield, quality characteristics and disease resistance were evaluated during a three-year period (2004 to 2006). Wine sensory analyses were performed and compared with international Vitis vinifera varieties. Even though no genotypes resulted adequate for market release, the results obtained confirm the potential importance of hybrids in an “eco-friendly” viticulture and identify the genotypes interesting for further investigation and breeding: GF 138-3 and GA 48-12 showed good agronomic performance, resistance to more grape diseases and high quality wine.
Successful viticulture must meet the requests of consumers and growers for good wine quality, disease and insect tolerance and low environmental impact [1,2]. Recurrent environmental issues have increasingly sparked political-social discussions over the last ten years. The European agricultural policies implemented guidelines focused on improved management strategies, integrated agronomic practices in the vineyard (2009/128/CE Directive) and a reduction in the use of pesticides and fungicides, using more disease-tolerant varieties in place of conventional ones. Hybrid varieties could be the most promising tool for low input, low cost and time-saving viticulture because of their tolerance to diseases and insects [3,4]. The wine industries in many extra-European Union countries currently use a high percentage of inter-specific varieties with good results and fund specific breeding programmes [
Since 1960, inter-specific varieties had been used to successfully introgress tolerance to pests and diseases, such as powdery mildew (Erysphe necator Schwein), downy mildew (Plasmopara viticola) or phylloxera (Dactulosphaira vitifoliae Ficth.) [6-8]. These varieties are the result of efforts to combine the quality of traditional European varieties (Vitis vinifera) and pyramid different resistance traits typical of American varieties (Vitis riparia, Vitis labrusca, Vitis aestivalis, Vitis berlandieri and Vitis amurensis). Inter-specific breeding was especially important after the massive destruction of European vineyards, as consequence of the invasion of serious fungal diseases from the US during the second half of the 19th Century. At the beginning of 20th century, over 6000 hybrids were registered in Europe. Unfortunately, the offspring of these varieties often lose the stable yield and good quality traits of their European parents due to the complex polygenic base, which governs the resistance and the quality of the grapes [9,10], demonstrating that inter-specific breeding methods are quite unsuccessful. Finally, the diffusion of pesticides, the employment of the first rootstocks tolerant to phylloxera, the low quality of wines obtained and the possible presence of toxic metabolites have led to the unpopularity of hybrids [11,12]. Since then, crosses have been only performed in Germany [7,13], Austria [
Currently, the promising market of hybrids was first established through the cultivation of “Regent” in Germany, where it is grown over an area of more than 600 ha; a future similar trend in Europe, particularly in Italy (INFOAM 2000; Deutsches Weinbaujahrbuch 1995- 2003), can be foreseen. As soil, location and climate (typically referred together as Terroir) play a central role in vine performance and wine qualitative characteristics, the relationship between the hybrids and the environment is a crucial aspect that must be considered to evaluate their potential adoption in the investigated area. Thus, the aim of this study was to survey phenological, agronomic and qualitative performances, along with their resistance to the most common vine diseases, of 19 European wine grape hybrids.
The 19 inter-specific red and white wine grapes varieties, listed in
were replanted in an experimental vineyard located near Motta di Livenza (Treviso, Italy 45˚47'5.91''N, 12˚35'38.90''E).
The hybrids were monitored for 3 years (2004 to 2006) and compared for agronomic parameters and disease resistance with “Pinot gris”, as this is an international cultivar widely cultivated in the area. The site is characterrised by a heavy soil (35% - 40% of clay). The climatic data accumulated for 3 years of study, are reported in
The main phenological stages, such as budbreak, bloom and veraison (defined as 50% of plants upon the
stage) were evaluated and the variation quantified using standard deviation. Sugar accumulation and acid degradation were monitored upon the initiation of veraison (data not shown) to determine the ripening level and the harvest time. The shooting percentage (shoots/buds), potential fruitfulness (bunches/shoots) and real fruitfulness (bunches/buds) were determined for all the varieties. The real fruitfulness of the first four buds of each cane was also determined in 2005. All these parameters were compared among the hybrids and to “Pinot gris”. At harvest, the average cluster weight and yield per vine were determined. The grape quality was analysed by measuring the soluble solids, titratable acids and pH using a digital refractometer (ATAGO PR-101), a manual titrator (Digitrate Pro 500-Jencons) and a Crison pH metre, respectively.
Based on the agronomic and grape qualitative data, 0.3 tons of grapes from only the most promising varieties were harvested yearly and microvinified (
Taste panelists evaluated the general organoleptic characteristics, such as aroma and flavour intensity, complexity, balance, structure and finesse.
The wines from two of the most widespread varieties cultivated in the area were used as standards for the sensory analysis. “Pinot blanc” was used as a standard for white wines, as it presents more neutral aroma than “Pinot gris”, and “Franconia” was used as a standard for the red wines. Both standard wines were obtained using
• marks up the year of microvinification.
grape from the experimental site and by using the same winemaking process adopted for the hybrids.
The damage caused by the most common diseases associated with North-Eastern Italy climate (Downy Mildew, Botrytis and Black Rot) was assessed at harvest in 2004 and 2005 using visual inspections and evaluating leaves and bunches separately. A total of 150 clusters and 200 leaves sampled from different parts of the grapevines for each replicate were used in the assessment. Infected leaves or bunches were ranked according to a scale: 0 = no symptoms; 1 = 1% - 10%; 2 = 10% - 25%; 3 = 25% - 50%; 4 = 50% - 75%; and 5 = 75% - 100% of infected leaf areas or infected berries per bunch, respectively. The data regarding disease severity were processed according to Townsend-Heuberger formula [
where I% = percentage of infection; n = number of leaves or bunches in each class; v = class value; z = highest class value; N = total amount of assessed leaves or bunches. The data were statistically analysed using ANOVA and Duncan’s multiple range test, using the statistical package “Statistica 8.1”, (StatSoft Inc., 2007). The average, standard deviation and P were calculated.
The full phenological expressions of the hybrids demonstrated their adequate adaptation to the North Italian area. The mean dates for the three years, relating to the phenological stages, compared with “Pinot gris”, are reported in
“Pinot gris” is considered as an early wine grape variety, registering budbreak in the first/second decade of April, flowering in the first 10 days of June, and veraison in the last decade of July. The phenological data showed a high variability among genotypes in the budbreak phase (
Cluster weight (g) and yield values (kg/vine) of these cultivars showed an opposite trend compared with “Pinot gris”, as cluster weight was, on average, lower (137 g) than that of “Pinot gris” (167 g;
Note: Letters represents the significance of variability among the hybrids with p < 0.05 (Duncan test).
Note: Letters represents the significance of variability among the hybrids with p < 0.05 (Duncan test).
was significantly high, with over 20 t/h obtained for the most productive hybrids and 4 - 5 t/ha obtained for the least productive varieties. On average, the hybrids produced more (8.1 kg/vine) than “Pinot gris” (7.3 kg/vine), suggesting fruitfulness, as reported by previous studies [30,31]. The most productive varieties were “Sirius”, “Regent”, “Seibel 7052”, “Orion”, “GA 48-12” and “GM 7743-8”, all presenting a yield greater 9 Kg/vine. Overall, we observed high variability among the different genotypes. Over the three-year period, the “Regent” and “Ambror” registered the highest variation. The soluble solids, titratable acids and pH values were measured to assess the grape quality [
(18.1˚ Brix), while “Staufer” recorded the lowest value (14.8˚ Brix). A comparison of the yield per vine (
sponded with a similar increase in pH values in must. As Keller [
Regarding the wine characteristics and quality, in 2004 no white wines obtained from these hybrids performed as well as the reference commercial variety (“Pinot blanc”;
Concerning red wines obtained from hybrids, the quality was lower than the reference variety wine (“Franconia”) in all three years (Figures 4(b), (d) and (f)). In 2004 (
The percentage of Downy Mildew, Botrytis and Black rot infection is reported in
Viticulture in North-Eastern Italy is difficult due to the high incidence of Downy Mildew and Botrytis, resulting from high rainfalls and air humidity. Unlike other European countries, e.g., France and Spain, Italy needs to drastically limit the spread of fungal diseases. The necessity of a more sustainable viticulture urgently requires the identification for new vine genotypes resistant to the more common vine diseases and the production of wine according to commercial qualitative demands. Specific
Note: Letters represents the significance of variability among the varieties with p < 0.05 (Duncan test).
studies concerning the cultivation and potential comercial use of hybrids in North-Eastern Italy have not been previously conducted. Although stringent European Union rules strictly limit the use of these hybrids, and advantages and drawbacks of their employment are being discussed, the results obtained from the present study indicated that breeding programmes must be pursued.
None of the hybrids under study showed high values for all agronomical characteristics tested, nor a global quality sufficient to suggest their direct application in organic viticulture. Furthermore, the high variability among the genotypes observed for agronomic, phenological and qualitative performances could provide choices suitable to different and specific oenological goals. Among the red wine cultivars, “SV 12-390” showed the lowest infection, adequate production (due to greater weight of the bunch) and a good overall wine quality. However, basing on the results obtained in the present research, our opinion is that “GF 138-3” is the most promising hybrid, showing a strong olfactory intensity, an interesting overall sensory quality and a low disease incidence. Schwab [
The further improvement of wine quality before the commercial release of hybrids is necessary. Moreover, research on agronomic practices aimed at improving the performance of single genotypes could reinforce the results obtained through breeding programme.
Thanks are due to Dr Alessandro Zanzotto for his contribute in the disease evaluation.