Vegetative , productive and qualitative performance of grapevine “ Cabernet Sauvignon ” according to the use of winter cover crops

Submitted on October 24, 2014 and accpeted on May 16, 2016. 1 Experiment carried out with resources of Embrapa and F APESC. 2 Universidade do Estado de Santa Catarina, Centro de Ciencias Agroveterinárias, Lages, Santa Catarina, Brazil. jcbettoni@gmail.com 3 Embrapa Produtos e Mercado, Canoinhas, Santa Catarina, Brazil. nelson.feldberg@embrapa.br 4 Embrapa Clima Temperado, Pelotas, Rio Grande do Sul, Brazil. gilberto.nava@embrapa.com.br 5 Epagri, Campos Novos, Santa Catarina, Brazil. milveiga@epagri.sc.gov .br 6 Epagri, Chapecó, Santa Catarina, Brasil. lpwild@epagri.sc.gov .br *Corresponding author: jcbettoni@gmail.com Vegetative, productive and qualitative performance of grapevine “Cabernet Sauvignon” according to the use of winter cover crops 1


INTRODUCTION
Cover crops play fundamental roles in agricultural ecosystems by preserving and enhancing physical, chemical and biological structures of the soil.These are long term structural changes with the least possible impact on natural resources.Among the most significant effects of cover crops are the weed control, erosion reduction and the increase in the content of organic matter in the topsoil.The first works carried out in the South of Brazil to stimulate the cultivation of cover crops in vineyard soils were developed in the mid-1980s, in the municipality of Bento Gonçalves, state of Rio Grande do Sul (Pancotto et al., 2004).Since then, the use of this practice has been intensified, although today most of the orchards are planted in completely bare soil, through routine application of herbicides.
The use of soil cover in the orchards reduces and even eliminates the use of herbicides.The effect of cover plants on weeds may be suppressant by means of plant mass deposition and even allopathic effect with the release of allele chemical that inhibit the growth of weeds (Bettoni et al., 2011;2012).
The benefits of soil cover use are shown in studies demonstrating increases in the grape crop yield (Dalbó and Becker 1994;Zalamena et al., 2013a).The effects of vegetation cover in the increase of yield are observed when coverage is carried out in the dormant period of the vines.On the other hand, whether the soil is permanently covered, the effect starts competing with the vine for nutrients, and especially for water (Murisier & Calame, 1987;Dalbó and Becker, 1994).Under certain conditions, the cultivation of perennial cover crops may be an interesting alternative, especially in soils with high content of organic matter.By proving this statement, Zalamena et al. (2013a) and Zalamena et al. (2013b) observed in soils with high levels of organic matter that the cultivation of tall fescue (Festuca arundinacea) may be a viable alternative to reduce the vigor of the vine, producing wines with higher content of anthocyanins and total polyphenols.
Another interesting effect of the use of cover crops was observed by Botton et al. (2010), who found a lower infestation of urhizococcus brasiliensis in areas maintained with vegetation cover than in areas without coverage, which can be attributed to the ease of to plague to locate the vine plants, as they are the only hosts in the area with no plant protection.
A large number of plant species has potential for being used as a soil cover plant.However, for the selection of the most suitable species for cultivation in a given local, the adaptability capacity of each species to the existing conditions in the vineyard should be considered, as some unfitted species may produce less biomass than the typical weed in the cultivation area (Bugg et al., 1996).According to Agostinetto et al. (2000), the plant mass of the aerial part produced by plants and their soil covering capacity are important parameters that should be used to evaluate the suitability of species.
The growing of soil cover crops in vineyards is a practice that has been increasingly adopted in southern Brazil in the winter period.However, due to the limited availability of experimental results with species of plants suitable for this purpose, it is necessary to carry out studies to verify their effects on vegetative, productive and qualitative behavior of "Cabernet Sauvignon" grapevines.(Embrapa, 2013) whose area is in a region with climate characterized as Cbf, according to Köppen classification (Pandolfo et al., 2002).

MATERIAL AND METHODS
For the formation of the orchard, seedlings of "Cabernet Sauvignon" grafted on Paulsen 1103 rootstock were planted in the spacing of 1.5 x 3.0 m and plants conducted in trellis system.Before orchard implementation, fertilization and liming were carried out, based on the chemical analysis of the soil (Table 1).After the implementation of the orchard, crop management consisted of manual weeding on the planting rows and mechanical mowing between rows without the application of herbicides.
Orchard fertilization, which until the beginning of the experiment was done in the row of the crop, was the application in total area of 150 kg ha -1 N as urea, 100 kg ha - 1 P 2 O 5 as triple superphosphate and 120 kg ha -1 K 2 O in the form of potassium chloride.About 50% of the phosphorus amount and 25% of potassium dose was applied at sowing of cover crops, associated with the application of 1.5 t ha - 1 of dolomitic limestone.The rest of the rates of the fertilizers was split and applied during the vegetative cycle of the grapevine, starting about 15 days after sprouting and extending until the color change of the berries.
Cover crops were sown by throwing all over the plot area in June of each year, with mild incorporation by using hoe and managed by mowing at their full bloom.Each plot consisted of an area of 45 m 2 of vegetation, made up of five grapevine plants, where one plant of each end was borders, evaluating the three central plants.The experimental design was a randomized block design with four replications.
At the time of fruiting pruning, the number of rods and the mass of the pruned material per plant were determined.After bud sprouting, the number of branches per plant was determined.Before harvest, 100 berries were collected randomly on the useful area of each plot, located in the apical, median and basal areas of different clusters on both sides of the plant to determine the total soluble solids, titratable acidity and pH, using methods described in Rizzon (2010).At harvest, which occurred in April of each wine harvest, the number of bunches per branch, the number and weight of bunches per plant and the average weight of bunches per plot were determined.
The nutrient content in the leaf tissue of grapevines was determined on samples collected at the time of color change of the skin, consisting of 50 petioles of newly matured leaves per plot for analysis of N, P, K, Ca, Mg, Fe, Mn, Zn and B, according to the methodology described in Tedesco et al. (1995).Fresh and dry mass yields of cover crops and weeds were determined at the time of full bloom.The samples were collected 1.0 x 1.0-m square by cutting the plant material close to the ground, collecting three subsamples per plot, one in the row and two in between the rows.After collection, cover plants were separated from weeds and weighing of the fresh mass of both (FM t.ha -1 ) was carried out.Subsequently, the samples were dried in an oven at 60°C, until constant weight to determine dry matter (DM t.ha -1 ).
Data were submitted to analysis of variance, and when significance was tested by the F test, the averages were compared by the test of Tukey at 5% of error , using the statistical program SISVAR 5.0 (Ferreira, 2011).

RESULTS AND DISCUSSION
Biomass yield differed among winter cover crops, where lower yield was found in productions of red and white clover, which produced insignificant quantities in the first harvest (Table 2).The highest biomass yield (FM t.ha -1 ) in the first year was achieved in vetch crop, followed by ryegrass and turnip, with production of 30.0; 22.9 and 19.7 t ha -1 , respectively.However, when comparing the dry matter production, which ultimately is what really remains on the ground, no statistical difference between the cultivated species was found, except for the clovers.In the second harvest, the production of biomass (FM t.ha -1 ) followed the same trend of the previous harvest; however, when dry matter production (DM t.ha -1 ) was compared, ryegrass stood out, with 5.25 t ha -1 , followed by rye, vetch and black oat.The smallest yield of biomass (FM t.ha -1 ) was found in wild turnip and gorga, with 2.63 and 1.92 t ha - 1 , respectively.Similar to the previous harvest, the insignificant biomass yield of clovers was evident due to low capacity of establishment, which associated with the slow initial growth of this species is muffled by the spontaneous vegetation.
Regarding the percentage of dry mass of cover crops, rye showed the highest index in the two evaluated harvests, indicating lower water content in plant tissue when compared with other species (Table 2).The great potential of plant mass of rye was also found in a study carried out in the state of Paraná by Derpsch et al. (1987) and in Santa Catarina by Wildner and Dadalto (1992).This larger yield of rye biomass, associated with its high C/N ratio (Doneda et al., 2012;Wildner and Dadalto, 1992), makes this species an interesting option for land cover in vineyards, especially in soils with low content of organic matter as it promotes accumulation of persistent dry matter on the soil surface in addition to reducing the harmful effect of water runoff and reduces the impact of rain water drops on the ground, promoting nutrient cycling and maintaining water infiltration in the soil profile.The reflection of adaptability capacity and establishment of cover crop species is shown in Figure 1.The rye, among the evaluated species, presents more dominance in relation to the weeds, around 90% of dry matter produced in the winter cycle followed by ryegrass, black oats, wild radish, vetch, gorga and clovers.The effect of cover crops on weeds is normally suppressive due to the rapid establishment and initial growth, characteristic not presented by species of clover.In addition to the dominance of cover crops on weeds in dormant stage of the grapevine, there is also the effect of the remaining mulch after the management of green mass on the growth of weeds (Bordelon & Weller, 1997), as well as nitrogen fractionation (Brunetto et al., 2011), increase in the content of organic matter in the soil (Faria et al., 2007) and grape productivity (Dalla Rosa et al., 2009), with no effect on their quality.
The production of grapes and its income components were not affected by treatments in the two evaluated crops (Table 3).However, in the second harvest, grape production was 9.55 t ha -1 , in the average of treatments, 56.4% higher than in the previous harvest, possibly associated to climatic conditions that favor the production in this season.Similar results were found by Zalamena et al. (2013b) when evaluating a "Cabernet Sauvignon" vineyard in the Santa Catarina Plateau region, where no increase in the productivity of grapes was found using land cover plants during two evaluation crops.Even in the cultivation of nitrogen-fixing species such as vetch or clovers, increase in plant vigor was not found, probably due to the high content of organic matter found in natural conditions in soils of the Upper Valley of Rio do Peixe and that already meets the requirements of the crop for this nutrient.DM (dry mass); FM (fresh mass); % DM (dry mass /fresh mass x 100).Means followed by the same leeter in the column do not differ significantly from each other (p < 0.05).The total soluble solids content and pH in both harvests and the total acidity in the second crop were not influenced by cover crops, manual weeding and mechanical mowing (Table 4).In the first harvest, total acidity showed a significant difference among treatments with manual weeding and cover with vetch.However, the magnitude of the difference is very small, so that it does not affect substantially the quality of the wine.This similarity of the wort characteristics of the evaluated crops may be related to the absence of treatment effects on plant vigor and increase in the yield of grapes.
The species of cover crops and management of its biomass with manual weeding or mechanical mowing influenced the accumulation of nitrogen (N), phosphorus (P) and boron (B) on the petioles of the leaves at "Cabernet Sauvignon" grapes color change state (Table 5).A higher N content in the petioles of the leaves in the plots with vetch in relation to the ones in the oat plot, which presented N accumulation similar to other crop cover species and also to the management with hoeing or mowing.The higher N content observed on the cover with vetch, however, did not result in productivity gains and vegetative vigor as also observed by Dalbó and Becker (1994) in a study with using this species as cover crops in vineyard for four years.Thus, it can be inferred that gains in vegetative vigor, and even in grapevine productivity with vetch cover can be achieved in the long term only.
Higher levels of accumulated P and B in the petioles of the grapevine leaves were found when using the turnip as land cover plant, significantly differing from management with manual weeding and cover with vetch (Table 5).There are studies that report the rapid release of P and N in the decomposition of wild turnip (Ohland et al., 2005), with higher release rate up to fifteen days after plant mass management (Heinz et al., 2011).
Land cover is essential for the sustainability of the production system and the effects are likely to be more apparent over the years of using this practice.As the evaluation was conducted during two growing seasons, the effects of cover crops were not found in the increase of productivity and quality of the grapes produced; however, in the short term, it was possible to observe the suppressive effect on the weeds in vineyards grown with species of cover crops in the winter period, which can lead to a reduction in the use of chemical control, thus reducing the cost of grape production.ns -not significant.Means followed by the same leeter in the column do not differ significantly from each other (p < 0.05).

Figure 1 :
Figure 1: Dominance of cover crops over the weeds, in two wine harvests of soil management with winter cover crops on a grapevine orchard 'Cabernet Sauvignon'.RY: rye grass; BO: black oat; RG: rye grass; VE: vetch; WC: white clover; RC: red clover; WT: wild turnip; GO: gorga.

Table 2 :
Plant mass and dry matter percentage of winter cover plants in 'Cabernet Sauvignon'cultivar vineyard,in two harvests.Epagri, Videira, state of Santa Catarina

Table 3 :
Rods, branches and clusters per platn and cluster weight per plant, production, cluster average weight and cluster per branch of 'Cabernet Sauvignon' grapevine in two wine harvests.Epagri, Videira, state of Santa Catarina ns -not significant.

Table 4 :
Total soluble solids content (TSS), pH and total acidity of 'Cabernet Sauvignon' grapevine in two wine harvests.Epagri, Videira, state of Santa Catarina -not significant.Means followed by the same leeter in the column do not differ significantly from each other (p < 0.05). ns

Table 5 :
Average nutrient content on the petioles of the leaves at "Cabernet Sauvignon" grapes color change state in two wine harvests with manual weeding, mechanical mowing and winter crop cover species.Epagri, Videira, state of Santa Catarina