| Abstract | ‘Graševina’ predstavlja najznačajniju sortu vinove loze u Hrvatskoj, koja zauzima gotovo jednu četvrtinu svih vinogradarskih površina u zemlji.
‘Graševina’ se uzgaja uglavnom u regijama kontinentalne Hrvatske, s posebnim naglaskom na vinogradarskoj regiji Slavonije i hrvatskog Podunavlja, gdje se nalazi 85 % posađenih vinograda. Klonska selekcija ‘Graševine’ započela je 2004. godine u kutjevačkom vinogorju. Kroz postupak masovne pozitivne klonske selekcije ustanovljena je unutarsortna varijabilnost unutar populacije, što je omogućilo izdvajanje perspektivnih klonskih kandidata. Nakon zdravstvenog testiranja, broj klonskih kandidata sužen je na dvanaest, koji su se istaknuli po pozitivnim karakteristikama u odnosu na prosjek populacije. Na tim kandidatima nastavljen je postupak individualne klonske selekcije.
U ovom istraživanju provedena je evaluacija učinkovitosti individualne klonske selekcije kod sorte ‘Graševina’ u završnoj fazi, s ciljem identificiranja najperspektivnijih kandidata za daljnju registraciju klonova. Poljsko istraživanje je obuhvatilo dvije godine (2015. i 2016.) na jednoj lokaciji (Radovanci) te je analizirana varijabilnost 12 klonskih kandidata ‘Graševine’ posađenih na dvije različite podloge (Vitis berlandieri x Vitis riparia K5BB i Vitis berlandieri x Vitis riparia SO4). Podaci o prinosu i uvometrijska mjerenja su prikupljena za svaki klonski kandidat sorte ‘Graševine’. Kemijskom analizom provedeno je određivanje sadržaja šećera, ukupne kiselosti, pH-vrijednosti, koncentracije pojedinačnih organskih kiselina te analizu organskih hlapljivih spojeva koji doprinose aromi grožđa.
Utvrđene su značajne razlike između 12 istraživanih klonskih kandidata u svim ispitivanim svojstvima. Značajan utjecaj na njihova svojstva imale su dvije godine istraživanja sa značajnim razlikama u vremenskim uvjetima, kao i dvije podloge u istraživanjima. Dobiven je jasan uvid u razlike u aromatskom profilu istraživanih klonova te na koji način različiti vremenski uvjeti, posebno visoke temperature, ali i dvije istraživane podloge mogu utjecati na navedenu grupu spojeva kod ‘Graševine’. Dio rezultata ovog istraživanja korišten je u daljnjem vrednovanju sorte ‘Graševine’ i njenih klonskih kandidata, što je na naposljetku rezultiralo registracijom četiri klona: OB-412, OB-414, OB-435 i OB-445 u 2018. godini. |
| Abstract (english) | ‘Graševina’ is Croatia’s most important vine variety; almost 25 % of all vineyards are planted
with this variety and 38 % of produced grapes and 40 % of the registered produced wine in the
Republic of Croatia are made of ‘Graševina’. According to the Croatian Agency for Agriculture
and Food, wines produced from ‘Graševina’ accounted for more than 40 % of the total volume
of wine placed on the market (516,599 hL) in Croatia in 2022. The area of its cultivation is in
the continental regions of Croatia. It is most prevalent in the Slavonia and Croatian Danube
vineyard region, where 85 % of planted vineyards are located. Due to its adaptability and
consistent quality, ‘Graševina’ has become popular with both grape growers and wine
consumers.
Clonal selection is a thorough process to identify superior vines within a grape variety
population characterized by desirable agronomic traits that can be passed on to their
vegetative offspring. This process aims to enhance grape and wine quality, increase yield, and
improve the quality of planting material of cultivars under clonal selection. Criteria for selection
encompass factors like cluster size, disease resistance, acidity, sugar content, flavor and wine
aroma. Clonal selection also plays a pivotal role in preserving native grape varieties adapted
to local conditions, each with unique characteristics.
The clonal selection of ‘Graševina’ commenced in 2004, focusing on the Kutjevo vineyard area.
This initial mass clonal selection effort revealed intra-varietal variability, leading to the
identification of promising clonal candidates. Subsequent health testing narrowed down the
selection to twelve candidates with superior characteristics, initiating the individual clonal
selection process. This study investigates the efficiency of individual clonal selection for
‘Graševina’ in its final stage, based on detailed research on the production characteristics of
the most promising 12 clone candidates.
The research hypotheses were that between the clonal candidates ‘Graševina’ there are
significant differences in the basic production characteristics and aromatic compounds, and
that two rootstocks (SO4 and Kober 5BB) have a significant influence on the basic production
characteristics and on the content of aromatic compounds in the grapes of the clonal
candidates ‘Graševina’.
Materials and Methods section: The research was conducted over two consecutive years
(2015 and 2016), assessing the variability of 12 ‘Graševina’ candidates planted on two different
rootstocks, Vitis berlandieri x Vitis riparia K5BB and Vitis berlandieri x Vitis riparia SO4. The
experimental vineyard is situated in the Slavonia and Croatian Danube wine regions. The study
employed a randomized block design with three repetitions, each featuring a clone/rootstock
combination represented by 15 vines. Data on yield and bunch characteristics were recorded
during the harvest. The chemical analysis included sugar concentration, total acidity, pH value,
individual organic acid composition, and volatile compound analysis in grapes after harvest
determined by GC-MS.
The results: Results have showed the significant effect of clone candidates on all measured
parameters and confirmed the high variability level of 12 investigated clones. Significant effects
of different environmental conditions in two years of study were also detected for main
production characteristics and grape aromatic compounds. Higher temperatures and lower
precipitation levels were shown to have specific effects on different clone candidates. A
significant effect of two different rootstocks was also detected on only some production
characteristics and most aromatic compounds. The effect of rootstock on yield and cluster
characteristics was not significant. The interaction of clone candidates and rootstocks was not
constant in two years of study for basic production characteristics. Volatile organic compounds
analyzed in grapes of 12 clone candidates give us a detailed insight into the specific aroma
profiles of different clones but can also be used to define the variability of the ‘Graševina’ grape
aromatic profile. Aromatic profiles of clone candidates were also significantly affected by
differences in environmental conditions and two different rootstocks used in the research. A
higher content of aromatic compounds was detected in the second year of the study (2016),
which had moderate temperatures and higher precipitation.
It was possible to define more distant clone candidates based on multivariate analysis of
aromatic compounds detected in grapes of 12 clone candidates. This approach showed its
efficiency in detecting specific aromatic compounds contribution to discrimination among clone
candidates of ‘Graševina’.
Discussion: This study gives us a detailed insight into the characteristics of 12 clone candidates
of ‘Graševina’ in the final stage of individual clonal selection but also confirms the importance
of evaluating clone candidates’ aroma profiles in the clonal selection process. Considering the
differences detected among clones and rootstocks in two contrasting years, results are also
crucial in understanding the possible influence of climate changes on the performance of
selected clones combined with used rootstocks. Most of the results correspond with previous
research but with some exceptions in the case of rootstocks’ effect on essential production
characteristics of ‘Graševina’. The discussion pointed out the importance of aromatic
compound evaluation in the process of clonal selection, especially in the case of white
varieties. This study’s diversity of production characteristics has shown relatively high levels
compared to other cultivars. It is related to the long cultivation period of ‘Graševina’ in Croatia,
where it was not subjected to clonal selection, resulting in the high accumulation of mutations.
Conclusions: The first two research hypotheses were fully confirmed, confirming high variability
levels among evaluated clone candidates of ‘Graševina’ and significant differences in their
aromatic profiles. The hypothesis on rootstock’s effects on clone candidates’ production
characteristics is partially confirmed, even though their effect was significant in the case of
grape aromatic compounds.
Finally, this research contributes to the evaluation of ‘Graševina’ and selected clonal
candidates, resulting in the registration of four clones: OB-412, OB-414, OB-435, and OB-445,
in 2018. These findings significantly enhance the grape quality and aromatic profile of this most
important Croatian grapevine variety. |
