In the grape and climate sub-program we analyzed in detail the past and expected future developments of the climatic conditions and agro-climatic indicators in the Hungarian wine regions, while in the Eger, Tokaj and Mátra wine regions we performed special green works to increase the content parameters of grape and took precise microclimate measurements.
The impact of climate change on the past and future development of the climatic parameters in the Hungarian wine regions
It is very important for Hungarian viticulture to learn about the extent and direction of climate change in its wine regions in the coming decades. The time series of climate variables in many cases did not show a significant increase or decrease in many regions. Nevertheless, we believe that by presenting the direction and extent of the changes can effectively help growers in selecting optimal species and varieties, and planning on a longer time scale. With the help of the FORESEE database, we numerically analyzed the past and future climatic characteristics of the Hungarian wine regions. The database allows us to examine expected changes up to 2100 based on the results of 10 forecasting models. With the help of the Cool night-index, we examined how the color and flavor of grapes and wine will change in the future, i.e., to what extent we can expect changes in the taste and aroma components in the coming decades. The hydrothermal coefficient (HTC) developed to express the combined effect of precipitation and temperature on grapes was analyzed to determine how the thermal and hydrological conditions of wine regions meet the environmental needs of grapes. The magnitude of downy mildew risk was quantified using the precipitation-heat index (IP). If the index value is IP> 4, the risk of downy mildew is very high. In Hungary, the value of the IP index in downy mildew free vintages is between 2.3 and 3.5. Using the heliothermal index developed by Huglin, we determined which grape varieties suit our climatic conditions.
Microclimate studies in the grapevine’s fruiting zone
If we continuously measure the microclimatic parameters of the fruiting zone, we can model the development and mass growth of the stock. In addition, we have the opportunity to determine the critical periods of development when temperature or humidity conditions can significantly affect yield formation or yield growth, as well as the value of quality indicators. If we know which weather factor poses what degree of risk to the development of the stock, we will have the opportunity to take preventive action in time against possible adverse effects.
Studies of the microclimate of the grapevine’s fruiting zone
In the Eger and Tokaj wine regions, we performed climatic measurements in the fruiting zone at 6 locations:
Felsőtárkány - Nyavalyás 227,4899m E20° 24' 22,00" N47° 57' 23,09"
Eger - Nagy-Eged-hegy 347,0876m E20° 24' 50,39" N47° 55' 20,62"
Bodrogkisfalud - Patrícius 161,6066m E21° 21' 37,20" N48° 11' 32,35"
Sátoraljaújhely - Boda 191,125m E21° 38' 37,69" N48° 24' 12,97"
Tarcal - Nyulas 148,8796m E21° 22' 37,35" N48° 08' 45,88"
Mád - Szent Tamás 210,7754m E21° 17' 40,18" N48° 11' 29,65"
In the evolution of the grape climate, it is also important to separate those microclimatic layers and zones, for which we can study the temperature, humidity, wind speed and radiation conditions. In addition, we can analyze the interception loss of water of grape stands due to different cultivation methods.
Photos of the microclimate stations, with the names of the vineyards, are shown below (Picture 1)
Boda dűlő Nagy-Eged hegy Nyulas dűlő
Patrícius dűlő Szent-Tamás dűlő Nyavalyás dűlő
Figure 1. Microclimate measuring stations and their locations in the Tokaj and Eger wine regions
The rapid development of remote sensing in the near future may allow the measurement of microclimatic characteristics using satellite data. At present, however, the stock microclimate cannot be produced with sufficient accuracy with the available 1-1 km grid interpolation, taking topographic models into account, we can only estimate the daily values and averages and extremities of the indicators with a significant error percentage.
The macroclimate data produced by interpolation showed a good agreement with the measured microclimate data in the case of the daily maximum temperatures, but the microclimate and macroclimate differed significantly in the case of the minimum temperatures. It can also be said that the microclimatic differences at the production site occur mainly at the dawn minimum temperatures. Plant evaporation and slope air mass advections can generate significant excess heat or even a lack of heat in the fruiting zone. Finally, with regard to precipitation, it can be noted that the micro- and macroclimatic differences are lower for smaller amounts of precipitation than for more intense precipitation like thunderstorms.
Special green work subprogram
The experiments were set up at four production sites in two wine regions (Eger and Mátra wine regions) in the 2018-2019 vintages. Special green works (early leafing, ringing, clustering) were carried out in each production area, which were primarily aimed at raising the quality parameters of the grapes. The studied varieties were Kékfrankos, Chardonnay and Ottonel muscat. The observations included the examination of the quantitative parameters of the crop (berry weight, berry skin weight, seed weight, cluster weight) as well as the qualitative, basic analytical parameters of the musts and wines. In addition to the basic analytical tests, aroma tests were also performed with a GC-MS instrument. The results show that the treatments had a significant effect on the quantitative indicators of the yield, although their effect depended significantly on the place of production and the vintage. Similar observations can be made with respect to basic analytical data. We can say that the special green works basically accelerated the ripening processes. In connection with technological maturity, cluster thinning can be highlighted, which generally resulted in higher sugar and lower acidity. However, the skin / berry ratio was higher in the ringed and leafed treatments, which had a significant effect on other content values. This is also confirmed by aroma measurements of musts and wines. It can be said that each treatment was characterized by different intensities of different aroma components, even if there was no significant difference in the basic analytical results. Overall, we can say that the leafing had a positive effect on the ripening of the grapes, but the nature of the place of production and the vintage can significantly influence its extent.