Rakonczás Nándor

Dr. Rakonczás Nándor

Institute of Horticultural Science, University of Debrecen, Debrecen, Faculty of Agricultural and Food Sciences and Environmental Management, Debrecen, Hajdú-Bihar, Hungary
orcid

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 June 2023 in Plants
Verified
Journal Article
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Csótó AndrásCsótó András
Csótó András
Antal NagyAntal Nagy
Antal Nagy
NLNóra Laurinyecz
Nóra Laurinyecz
ZNZora Annamaria Nagy
Zora Annamaria Nagy
CNCsaba Németh
Csaba Németh
ESErzsébet Sándor
Erzsébet Sándor
Grape production worldwide is increasingly threatened by grapevine trunk diseases (GTDs). No grapevine cultivar is known to be entirely resistant to GTDs, but susceptibility varies greatly. To quantify these differences, four Hungarian grape germplasm collections containing 305 different cultivars were surveyed to determine the ratios of GTDs based on symptom expression and the proportion of plant loss within all GTD symptoms. The cultivars of monophyletic Vitis vinifera L. origin were amongst the most sensitive ones, and their sensitivity was significantly (p < 0.01) higher than that of the interspecific (hybrid) cultivars assessed, which are defined by the presence of Vitis species other than V. vinifera (e.g., V. labrusca L., V. rupestris Scheele, and V. amurensis Rupr.) in their pedigree. We conclude that the ancestral diversity of grapes confers a higher degree of resilience against GTDs.

11 January 2023 in Foods
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Rakonczás NándorRakonczás Nándor
Rakonczás Nándor
ZKZoltán Kállai
Zoltán Kállai
Kovács BélaKovács Béla
Kovács Béla
GAGabriella Antal
Gabriella Antal
Szabó SzilárdSzabó Szilárd
Szabó Szilárd
Imre HolbImre Holb
Imre Holb
Bentonite fining is one of the generally applied wine-making technological elements that may seriously affect wine components. The aim of this study was (i) to investigate the effect of 21 bentonite products on eight oenological parameters, 19 elements, 21 volatile organic compounds (VOCs) and 10 organoleptic properties of white wine; and (ii) to quantify intercorrelations among the parameters separately for each of the four quality attributes. Among oenological parameters, sugar, acidity, malic-, lactic-, citric acid and total phenol contents were significant among several bentonite products. The amounts of elements were the lowest in the control wine treatments (with exceptions of, e.g., Ni and Cu); and these values were significantly different from several bentonite products. The relative presence of the VOCs was above 100% for most VOCs, but it was below 100% for 1-propanol, 4-amino-1,5-pentandioic acid and butane-dioic acid, and diethyl ester in all treatments. For organoleptic parameters, the values of clearness, colour, flavour intensity and taste persistency was the lowest in the control wine treatment, while the values of flavour character, flavour quality, taste intensity, taste character, and overall harmony were the highest for the bentonite products of AP, EBE, M-SA, EBE, EBE, respectively. Results of correlation and factor analyses showed strong intercorrelative effects of bentonite fining on the four quality attributes. In conclusion, this study can help in the proper choice of a specific bentonite product in relation to complexity effects of bentonite fining.

20 September 2015 in International Journal of Horticultural Science
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Journal Article
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Rakonczás NándorRakonczás Nándor
Rakonczás Nándor
DAD. Andrási
D. Andrási
ZMZ. Murányi
Z. Murányi
Mineral composition of wines is affected by many ecological and technological factors. These variables are mostly discussed focusing on certification of origin and human health. This paper gives data on possible changes in mineral composition and pH of wines due to 4 hours skin maceration (1st trial) and fermentation sur marc (2nd trial). Experimental site is situated on acidic sandy soil in middle east Hungary. The variety collection was established in 2003 with own rooted planting material in 3x1 m spacing, trained for single curtain trainingsystem. Mineral composition of wines was determined with ThermoFischer Scientific iCAP 6300 ICP-OES, pH was measured with pH10pen (VWR International) in field, and with SevenEasyTM pH meter (Mettler Toledo) in laboratory. 1st trial with 9 PIWI white wine grape varieties pointed to demonstrate effects of skin maceration, which is abundantly used to elevate aroma content. 2nd trial with the use of ‘Medina’ red PIWI grape variety aimed to demonstrate effects of double pasta skin maceration in rose and red wine technology. Data of 1st trial show, that K, Cu, Mn and P respective increase with skin maceration, despite Fe show considerable decrease. Data of 2nd trial show, that K, Mg, Mn, P, Sr and B increase with longer skin contact and higher fermentation temperature, despite Fe and Ba decrease with this technology. In regard to pH, data show, that skin maceration and fermentation sur marc increase K content with about 30-70% respectively, withstanding that pH also increase with a considerable 0,4-0,5 value. K content can be higher in the end product, despite to earlier higher level of tartrate formation. An attention should be driven to lower level of tartaric acid and consequently higher pH characteristic for wines produced with the application of skin maceration or fermentation sur marc.

26 September 2006 in International Journal of Horticultural Science
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Journal Article
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IGI. Gonda
I. Gonda
LLL. Lakatos
L. Lakatos
Rakonczás NándorRakonczás Nándor
Rakonczás Nándor
IHI. J. Holb
I. J. Holb
The aim of this study was to measure the solar radiation conditions in the tree and around the tree of pruned (summer pruning) and unpruned trees in an intensive apple orchard. When observing the daily trend of global radiation measured, there was a great reduction at midday hours due to the shadowing effect of the canopy. The reduction reached 70-75% before pruning, while after pruning it was only 20-25%. The relative radiation supply of the canopy space on cloudy days in the morning and late afternoon hours was higher than that of the sunny days. Mean differences between the day and night temperature reduced greatly in the period of intensive fruit colouration in August and September both in the plant stock and outside the plant stock.

19 December 2019 in International Journal of Horticultural Science
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Rakonczás NándorRakonczás Nándor
Rakonczás Nándor
National wine strategy of Hungary promotes the use of “flexible” grape cultivars. These enable producers’ best fit to wine market changes and expectations. This study is aimed to present data on the gene bank of the University of Debrecen, Hungary. Data were collected at a single site, between 2010 and 2018 in east Hungary lowland on acidic sandy soil, own rooted planting material. Our results showed that besides high yield and adequate cane production desired sugar content at convenient pH is to be awaited with moderate deviation between vintages. Presented concept demonstrate technological flexibility of cultivars by their average deviation from regression equation between increasing sugar and pH typical for the vintage composed of data of cultivars of the gene bank. Average positive deviation means higher sugar content at specific pH, thus higher sugar content at desired, conveniently low pH (3.0-3.2 pH).

19 April 2023 in Preprints.org
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Csótó AndrásCsótó András
Csótó András
Antal NagyAntal Nagy
Antal Nagy
NLNóra Laurinyecz
Nóra Laurinyecz
ZNZora Annamaria Nagy
Zora Annamaria Nagy
CNCsaba Németh
Csaba Németh
ESErzsébet Sándor
Erzsébet Sándor
Grape production worldwide is increasingly threatened by grapevine trunk diseases (GTDs). No grapevine cultivar is known to be entirely resistant to GTDs, but susceptibility varies greatly. To quantify these differences, four Hungarian grape germplasm collections containing 305 different cultivars were surveyed to determine the ratios of GTDs based on symptom expression and mortality rate. The cultivars of monophyletic Vitis vinifera L. origin were amongst the most sensitive ones, and their sensitivity was significantly (p<0.01) higher than that of the interspecific (hybrid) cultivars assessed, which are defined by the presence of Vitis species other than V. vinifera (e.g. V. labrusca L., V. rupestris Scheele, V. amurensis Rupr.) in their pedigree. We conclude that ancestral diversity of the grape confers higher degrees of resilience against GTDs.