ROOTSTOCK COMPETITION AND PLANTING SPACING FOR CV. ‘VERMENTINO’ IN AN ALTITUDE REGION OF SANTA CATARINA

SUMMARY Rootstock adequacy and planting density are necessary for new grapevine varieties in new regions. The objective of this work was to select the rootstock that confers the best productive performance to the ‘Vermentino’ variety, and to adjust the ideal spacing for this combination. The experimental design used was randomized blocks in a 5x3 factorial scheme, in which the treatments studied consisted of the combination of five rootstocks (‘101-14 Mgt’, ‘Harmony’, ‘IAC 572’, ‘Paulsen 1103’, and ‘VR 043-43’) and three spacings between plants (1.0, 1.2 and 1.5 m). The phenological cycle of the plants and the productive and quality characteristics of the grapes were evaluated during 2018/19, 2019/20


INTRODUCTION
Vine cultivation is practiced in different regions of the world, where it consolidates and moves the market, generating wealth and income for the population. The altitude regions of Santa Catarina -Brazil, have stood out in the cultivation of fine wine grapes (Brighenti et al., 2014;Brighenti et al., 2015;Brighenti et al., 2016;Vianna et al., 2016;Nodari and Frank, 2019). In this sense, partnerships between the state government and the Autonomous Province of Trento made it possible to develop the project "Technology for the Development of Santa Catarina Vitiviniculture", to study and indicate grapevine varieties for the altitude regions of the state of Santa Catarina (Palladini et al., 2021). This project selected Italian varieties with the best enological and agronomic performance, which included the 'Vermentino' variety.
However, further research was necessary to choose the best spacing and rootstock combination for these varieties since this can influence the phenological and productive characteristics of the vineyard, as well as the quality characteristics of the wines (Brighenti et al., 2011).
The 'Vermentino' variety, also known as 'Pigato', 'Favorita', 'Piccabon', and 'Formentino', is recommended for the production of wines and sparkling wines (Souza et al., 2017), and can also be used as a table grape and for the production of homemade candies (Calò et al., 2006). When cultivated in Santa Catarina, its phenology is marked by medium budding and flowering, late veraison, and medium ripening (Porro and Stefanini, 2016). It has shown good productivity in regions above 900 m of altitude (Souza et al., 2017).
The appropriate rootstock combination contributes to the adaptation to different types of soil, and also influences the phenology of the plant, being an alternative adaptation to the climate specificities of each region (Hartmann and Kester, 1975;Tecchio et al., 2013;Allebrandt et al., 2015). In addition, rootstocks interfere with the vigor characteristics of plants grafted onto them, which is reflected in the vineyard productivity and management (Dalbó and Souza, 2019;Tecchio et al., 2019).
The different levels of vigor conferred by the rootstocks, in turn, require an adjustment in the density of plants in the vineyard since, with vigorous rootstocks, greater spacing between the plants is recommended so that there is space to hold a more significant load of buds per plant without excessive shading conditions (Santos, 2006).
Hence, the objective of the work was to select the rootstock that provides the best productive performance to the 'Vermentino' variety, and to adjust the ideal spacing for this combination.

MATERIALS AND METHODS
The experiment was conducted in a vineyard installed in 2016, located in the municipality of Água Doce -SC (1250 m of altitude), at the Villaggio Grando winery, in 2018Grando winery, in /19, 2019Grando winery, in /20, and 2020 cycles. The plants of the 'Vermentino' variety were conducted in an espalier with a spur cord pruning system. A 2.9 m spacing was used between rows, while the distance between plants varied according to the treatment. The climate of the region, according to the Koeppen classification, is Cfb, mesothermic, humid, without a dry season, and with a cool summer (Pessenti et al., 2019).
The experimental design used was randomized blocks, in a 5 x 3 factorial scheme (five rootstocks and three spacings), with four replications evaluated at two plants per plot.  Baggiolini (1952). Pruning was carried out by observing the swelling of the buds (a sign of breaking dormancy) on 09/12/2018, 09/12/2019 and 08/10/2020. The monthly and weekly precipitation and air temperature averages, as well as the accumulated cold hours (≤ 7.2 °C), were obtained by the Água Doce meteorological station, located at the Villaggio Grando winery, through the EPAGRI/CIRAM database.
To assess the productive parameters, fertility evaluations were carried out through: i) the direct counting of the number of branches and bunches per plant; ii) average pruning mass, obtained by weighing the branches pruned per plant in winter (g); iii) Ravaz index, by dividing the mass of bunches (yield, g) by the pruning mass (g); iv) number of bunches, counted individually on the marked plants and averaged per plant; v) the average mass of the bunch, obtained by the average weight of the bunches harvested per plant (g); vi) production per plant, based on weighing the bunches at the time of harvest (kg); vii) estimated productivity per hectare, by multiplying the production per plant by the number of plants per hectare (t/ha).
The harvests were carried out considering the health of the bunches and the ripeness of the grapes according to the total soluble solids content and total acidity.
The harvests took place on 18/03/2019, 03/03/2020, and 04/03/2021. Regarding the physicochemical parameters of the must, the total soluble solids content was evaluated and determined in a digital benchtop refractometer with automatic temperature compensation (QUIMIS®, Nova instruments, WYA -2S, Brazil), and the results were expressed as °Brix. In addition, the pH was determined directly in the must by a potentiometer (Meter AD1030, Adwa Instruments, Hungary), and total acidity was assessed by titration of the sample (Mettler 8603-Toledo, Switzerland) with a standardized solution of NaOH 0.1N, adopting pH = 8.2 as the endpoint of the titration, and the results were expressed as mEq/L. Total polyphenols of the must (mg/L) were determined by the Folin-Ciocalteu method (Singleton and Rossi, 1965) and the antioxidant activity of the must (µmol/L) was based on the DPPH assay according to the methodology described by Kim et al. (2002), using a UV-2601 spectrophotometer (Beijing Rayleigh Analytical Instrument Corporation, China).
The ANOVA assumptions were evaluated in the statistical analysis, with normality analyzed using the Shapiro-Wilk test and homoscedasticity using the Bartlett test. If the assumptions were not met, data transformation was performed. In the 2018/2019 harvest, the variables that required transformation were: yield, Ravaz index, total polyphenols, and DPPH. In the 2019/2020 harvest, the total polyphenols and pruning mass variables required transformation. In the 2020/2021 harvest, the total polyphenols variable was transformed. The transformations were carried out according to the method described by Box and Cox (1964).
The results were submitted to analysis of variance. and, in case of statistical significance, to an analysis of means by Duncan's test (p≤0.05).

RESULTS AND DISCUSSION
The vineyard's first harvest, 2018/19, was marked by frequent rains throughout the vine's reproductive period and mild temperatures during the fruiting period. The 2019/20 harvest was characterized by a drought that occurred in the months before the bud break and frequent rains during the months of grape ripening, together with mild temperatures. The 2020/21 harvest presented drought in September and October; however, it had frequent rains in November, December, and January, a period of flowering and development of the bunches, with mild temperatures for this period (Figure 1). The weeks that preceded the evaluated crops' harvest showed a predominance of cloudy days with frequent rains until harvest ( Figure 2). The frequency and distribution of rainfall are essential elements in fruit growing since the free water on leaves, flowers, and fruits is the main factor that can trigger the development of fungal diseases in the vine (Chavarria et al., 2007), indicating the need for alertness in the control of fungal diseases in the cultivation of the 'Vermentino' variety for this region In 2018/19, the sum of cold hours was 680 hours; in 2019/20, it was 405 hours; in 2020/21, it was 575 hours ( Figure 3). The species regulate the cold hours needed to overcome dormancy when this requirement is met. Dormancy depends on an environmental stimulus, mainly temperature and water availability, which provides adequate conditions for the beginning of bud break (Anzanello and Christo, 2020).  (Table  I).
No studies comparing rootstocks with the variety 'Vermentino' in Água Doce-SC were found in the literature; however, the commonly used rootstock is 1103P. For this scion-rootstock combination, Würz et al. (2017) observed average bud break, flowering, and veraison around September 20, November 24, and February 8 in São Joaquim-SC, respectively. Brighenti et al. (2014) observed the same region's mean dates between September 18, December 6, and February 9 for the bud break, flowering, and veraison, respectively.
Budburst occurred latest in the vines grafted onto 'Paulsen 1103' and 'VR 043-43' rootstocks in 2019/20 and 2020/21 (S-B) (Table II). This result is interesting because the classification based on the bud break can be used to choose varieties less prone to late frost risks (Würz et al., 2017).
The sub-period between budburst and flowering (B-F) was anticipated by these rootstocks, with an average difference of 4.5 days between the latest and the earliest rootstocks.  The difference in color change and harvest (V-C) subperiod was observed only in the 2020/21 harvest, for the 'Paulsen 1103' and 'VR 043-43' rootstocks. Brighenti et al. (2015) stated that in colder climate regions, varieties that have early ripening are indicated, while in warmer climates, varieties of late ripening are preferable because they have climatic conditions to complete maturation.
These differences may be related to variations in rootstock vigor levels, considering that vigorous rootstocks can prolong the vegetative cycle (Brighenti et al., 2011). Malinovski et al. (2016) observed an average cycle of 179 days for the 'Vermentino' variety in Água Doce-SC, which is similar to that observed in the present study in the 2020/21 harvest with 'Paulsen 1103' and 'VR 043-43' rootstocks.  Evaluating the productive parameters of the first crop (2018/19), no difference in the fertility index caused by the rootstocks and the spacing was found. Fertility is a genetic characteristic of grapevine varieties, and reflects the ability to differentiate vegetative buds from fruiting buds, which will determine their productivity (Meneguzzi et al., 2020).
Pruning mass was higher by using 'IAC 572' and 'Paulsen 1103' rootstocks. These rootstocks are considered vigorous (Dalbó and Feldberg, 2019); however, the Ravaz index indicates that only 'IAC 572' showed excessive vigor in this crop, with a 3.7 Ravaz index, and 'Paulsen 1103' was slightly above, which is accepted as appropriate for optimal ripening . Despite the low Ravaz index presented by the 'IAC 572', the production in several bunches did not show a significant difference, indicating that the vigor did not interfere with the fertility of the branches. The cluster mass was higher for Paulsen1103 rootstock, affecting production per plant and estimated yield (Table III).

Spacing
Means followed by the same lowercase letter in a column do not differ by Duncan's test (p>0.05); ns, not significant.
In 2018/19, pH variation promoted by the rootstocks was observed. However, all the musts had fair quality fermentation values (Brighenti et al., 2014). Higher total acidity and lower concentration of soluble solids were associated with 'IAC 572' and 'VR 043-43' rootstocks (Table IV). However, it is worth mentioning that the whole experiment was harvested on the same date, and this behavior may be related to the need for a longer period for grape ripening using these rootstocks due to their high vigor. Lower total polyphenols content and antioxidant activity were obtained with '101-14 Mgt' and 'IAC 572' rootstocks. Nevertheless, the amount and phenolic composition may vary according to different factors, such as grapevine variety, grape maturity, climate conditions, and exposure to ultraviolet light (Da Costa et al., 2021), and therefore its behavior over the years should be observed. Regarding the chromatic characteristics, differences were only observed for the Hue; higher values were related with '101-14 Mgt' and 'IAC 572' rootstocks (Table IV). This result may be related to the lower concentration of phenolic compounds associated with these rootstocks, considering that such compounds have an essential role in the color of wines acting as pigments (Bender et al., 2020).
The second crop of the vineyard (2019/20) presented the lowest fertility rate for the 'IAC 572' and 'VR 043-43' rootstocks. On the other hand, the pruning mass was superior to the 'IAC 572' rootstock in the spacings of 1.2 and 1.5 m between plants, following the exact behavior of the first crop. However, even with a statistical difference between the rootstocks, the Ravaz index values indicate an excessive vegetative vigor , especially in 'IAC 572' that presented the lowest index value, thus being seen again as the rootstock that confers more significant imbalance between vegetation and production.
In 2019/20, an increase in the number of bunches was observed when using the 'Paulsen 1103' rootstock followed by 'Harmony'. The lowest value of bunch mass was related to 'IAC 572'. These results demonstrate the need for adjustment in management to adapt to the vigor conferred by the rootstocks since excess or lack of vigor can lead to lower productivity (Grigolo et al., 2021), as observed in 'IAC 572' (Table V).
Grapes produced in 2019/20 with 'IAC 572', VR 043-42, and 'Paulsen 1103' rootstocks had a lower concentration of soluble solids content and higher total acidity regardless of the spacing used. As a result, these rootstocks are considered to be of increased vigor, and a more extended period may be necessary for grape ripening (Dalbó and Feldberg, 2019  Lower pH, in turn, was associated with 1.0 m spacing between plants when using the 'IAC 572' and 'Paulsen 1103' rootstocks, but in practice, this difference is not enough to change the quality of the must (Table VI).
The chromatic characteristics were not affected by the spacing between plants. The lightness of the sample, demonstrated that the musts have a clear and limpid aspect. The hue indicated that the musts exhibited a greenish yellow color when '101-14 Mgt', 'IAC 572' and 'VR 043-43' rootstocks were used, and greenish yellow with straw tones when 'Harmony' and Paulsen1103 rootstocks were used. The highest color chroma was verified in the musts associated with 'Harmony' rootstock (Table VI). Polyphenol content and antioxidant activity were influenced by the interaction between rootstock and spacing; the lowest levels in the 1.0 meter spacing between plants were observed when using '101-14 Mgt' and 'Harmony' rootstocks (Table VI). Despite the lack of information on the influence of these rootstocks on the polyphenol content and antioxidant activity of 'Vermentino' scion, Brighenti et al. (2014), studying Italian varieties in an altitude region of Santa Catarina, found higher levels of polyphenols in the 'Vermentino' variety and ascribed them to the influence of altitude and low temperature.
In 2020/21 there was no interaction between the factors spacing and rootstock on the vineyard production variables (Table VII). Following the behavior of the previous crop, the fertility index was lower, and the pruning mass was higher when using the 'IAC 572' rootstock, this same rootstock presented the lowest Ravaz index value, indicating excess vigor conferred by the rootstock.
The productive behavior for most rootstocks was adequate, showing that in the third year of vineyard production, the plants are already better established; even when young, the Ravaz index shows the best balance between vegetative and grape production .

Spacing
Means followed by the same lowercase letter in a column do not differ by Duncan's test (p>0.05); ns, not significant.
The number of bunches was lower when using the 'Harmony' rootstock, and this rootstock provided the lowest bunch mass, followed by 'VR 043-43' and 'Paulsen 1103', which was reflected in the production per plant and estimated productivity, where 'Harmony' and 'VR 043-43' had the lowest averages (Table VII). Regarding the spacing, a relationship between the number of bunches and bunch mass was observed; as the spacing increased, an increase in the number of bunches and the inverse in bunch mass occurred, evidencing the high fertility of buds (Porro and Stefanini, 2016). However, the highest estimated productivity was obtained with the spacing of 1.0 m between plants due to the greater number of productive plants with heavier bunches. The 'Vermentino' variety originally had medium vigor and produced bunches with medium to high mass (180-300 g), showing good productivity in the altitude regions of Santa Catarina (Palladini et al., 2021).

Rootstock
Means followed by the same lowercase letter in a column do not differ by Duncan's test (p>0.05); ns, not significant. TSStotal soluble solids; TAtotal acidity; L* -lightness. The 2020/21 harvest showed low values of soluble solids (Table VIII). This crop was characterized by constant rains and predominance of cloudy days during the grape ripening. These factors hinder the accumulation of soluble solids in the berries since the photosynthetic rate is reduced (Taiz and Zeiger, 2004). Nevertheless, Brighenti et al. (2014), studying the 'Vermentino' variety in the altitude region of Santa Catarina, obtained adequate values for the production of quality wines (18 to 22 °Brix). The total acidity of the musts was lower when using the 'Harmony' and 'Paulsen 1103' rootstocks, however, in the case of white wines, higher acidity values are acceptable, in order to give freshness to the wines, in this context, it is considered that all rootstocks presented good acidity values for the production of young wines (Porro and Stefanini, 2016). Acidity are correlated the pH, which ranged from 3.27 to 3.32. This parameter is crucial in the biological stability and color of wines, and the ideal range is between 3.0 and 3.6, depending on the type of wine (Wurz et al., 2022), which indicates adequate pH values for all the evaluated musts. The chromatic characteristics showedinteraction between rootstock and spacing, the variable L* presented the highest values when using the 'IAC 572' rootstock with 1.0 and 1.2 m spacing between plants, although all the rootstocks were associated with clear musts. The hue, revealed musts of yellow color with greenish reflections, although 'IAC 572' presented the highest values in the 1.2 m spacing. Chroma, in turn, indicates musts with lower color intensity (Chitarra and Chitarra, 2005).
The lowest concentration of polyphenols was ascribed to the rootstock 'IAC 572' in the spacing of 1.0 and 1.2 m between plants. This rootstock, being vigorous, can lead to imbalance in the direction of carbohydrates, the main precursors of polyphenols, which are directed to the vegetative apex and not to the bunches (Marcon Filho et al., 2015).
Likewise, of antioxidant activity was lower for 'IAC 572' at 1.0 and 1.2 m between plants. Antioxidant activity is the ability of a compound to inhibit or delay oxidation and lipid peroxidation, with phenolic compounds being the primary natural antioxidants. Its determination is vital to assess a food's ability to protect against deterioration, reactions that can decrease its quality, and nutritional value (Taiz and Zeiger, 2004).
Over the three seasons assessed, the tendency of delay in bud break can be observed when using more vigorous rootstocks, as well as the shortening of subsequent periods. This is an interesting behavior in plants grown in the altitude regions of Santa Catarina, since the risk of late frosts is high and the rainy period during ripening can harm the health and quality of the grapes for these regions. On the other hand, the last crop evaluated showed interesting yield values when the '101-14 Mgt' rootstock, with lower vigor, was used.

CONCLUSIONS
Under these experimental conditions, 'Paulsen 1103' and 'VR 043-43' rootstocks delayed bud break and shorten phenological sub-periods in young vineyards of the 'Vermentino' variety.
The 1.0 m spacing between plants contributed to greater productivity in vineyard of the 'Vermentino' variety.
The 'IAC 572' rootstock contributed the least to the increase in polyphenols and antioxidant activity of grapes from 'Vermentino' variety.
The 'Harmony' rootstock contributed to the greater accumulation of soluble solids in the grapes of the 'Vermentino' variety.