Non-irrigated Vineyard Research Articles

Effects of Severity of Post-flowering Leaf Removal on Berry Growth and Composition of Three Red Vitis vinifera L. Cultivars Grown under Semiarid Conditions

The effects of the severity of post-flowering leaf removal on the growth and phenolic composition of berry skin and seeds were studied in three Vitis vinifera L. genotypes over two consecutive seasons, 2007 and 2008. The study was conducted in a commercial vertical shoot positioned (VSP)-trained nonirrigated vineyard of northern Greece, planted with cultivars Merlot, Cabernet Sauvignon, and Sangiovese. Three different severities of leaf removal in the fruit zone were applied manually at berry set: nondefoliated (ND), removal of the lateral shoots of the first six basal nodes (LR), and full removal of the total leaf area (main leaves and lateral shoots) of the first six basal nodes (FR). Grape samples were obtained at commercial harvest. Leaf removal decreased yield per vine and cluster weight in Merlot and Sangiovese. Cluster compactness was reduced with the severity of defoliation only in Merlot, due to a decrease in berry number per cluster; berry fresh weight was unaffected in both cultivars. On the contrary, in Cabernet Sauvignon, yield was unaffected but berry size was restrained by leaf removal. Skin and seed mass followed variations in berry mass (except for seed mass in Sangiovese). Fruit zone leaf removal did not affect must soluble solids and increased titratable acidity only in Merlot. Defoliation increased skin anthocyanins in Merlot and Cabernet Sauvignon in the order FR > LR > ND but significantly reduced seed flavan-3-ols mainly as a result of the reduction in catechin and epicatechin amount. For these varieties, FR had lower seed flavan-3-ols than ND in both varieties, whereas LR had intermediate values. However, in Sangiovese, the highest seed phenolic content was recorded in LR. The results showed that post-flowering leaf removal improved the overall berry composition in Merlot and Cabernet Sauvignon but had limited effect in Sangiovese.

Cover Crop and Floor Management Affect Weed Coverage and Density in an Establishing Oregon Vineyard

Five vineyard floor management treatments were evaluated for effects on weed control over two growing seasons in an establishing ‘Chardonnay’ (Vitis vinifera) vineyard in the Willamette Valley of Oregon. Four cover crop management treatments and an unplanted treatment were compared to assess the effects on vine row and alleyway weed coverage and densities of broadleaf and grass weeds. A winter annual cover crop was grown in alleyways of the cover-cropped treatments and was mowed in spring. The mowed residue was managed as follows: 1) residue transferred in-row as mulch representing the industry practice of “mow-and-throw,” 2) residue transferred in-row as mulch at three times the rate of the earlier treatment, 3) mowed residue incorporated into alleyways, and 4) removal of mowed cover crop residue from the vineyard. Weed coverage was assessed visually within a 1.0-m2 quadrat placed randomly in alleyways and vine rows, and densities of broadleaf and grass weeds were determined by counting and grouping individual weeds within each quadrat. Vine row weed coverage and densities were lower in treatments with residue mulch at each sampling date in 2009 and 2010, with nearly 100% in-row weed suppression by the heavier mulch treatment. Alleyway weed coverage was lowest when residue was incorporated and highest in the unplanted treatment at some sampling dates. Grass weed densities in alleyways were similar between treatments at all sampling dates. Results of this study indicate that in-row mulch of cover crop residues at fresh weight densities of 2.5–15.0 kg·m−2 provided effective weed control in a non-irrigated vineyard in western Oregon. Also, alleyway weed coverage may be reduced through incorporation of mowed cover crop residues.

Double-pruning of "Syrah" grapevines: a management strategy to harvest wine grapes during the winter in the Brazilian Southeast

Grape harvest in the major grapevine growing regions of Brazil occurs during the summer; a period with excessive rainfall. The climatic conditions during the Brazilian summer can have an adverse effect on fruit maturation and wine quality. This study compared the performance of 'Syrah' grapevines cultivated in two growing seasons. A double pruning management system was employed as a technique in the vineyard and the grapevines were cultivated in summer, a cycle normally adopted in the South and Southeast of Brazil and winter during 2005 and 2006 in a non-irrigated vineyard. Vine water stress was minimal for both growing seasons and photosynthetic rates were found to be lower in the winter than the summer. However, no differences in vegetative vigor were observed. The growing season was shorter in summer than in winter. This was predominately due to a faster ripening period in the summer. During the winter harvests, grapevines had a higher yield, accumulation of sugar, anthocyanins and total phenolic compounds, and the lowest rot incidence. Double-pruning proved to be a powerful tool to improve wine grape composition in the Brazilian Southeast. This management will allow the production of quality raw materials for the production of good wines, allowing Southeastern Brazil to enter the competitive globalized wine market.

Transpiration efficiency of the grapevine cv. Semillon is tied to VPD in warm climates

Water-use efficiency in grapevines is dependent on the aerial and below-ground environment of the plant. Specifically, transpiration efficiency, the ratio of net carbon fixation to water loss, may be influenced by soil moisture and the leaf-to-air vapour pressure deficit (VPD) in the soil-plant-atmosphere continuum. The interactive effect of these abiotic parameters, however, has not been suitably investigated in field-grown grapevines. Accordingly, gas exchange of an anisohydric variety, Semillon, was assessed across a number of vineyards in two warm grape-growing regions of New South Wales (NSW) to ascertain how soil moisture and VPD interact to affect transpiration efficiency at the leaf level. Leaf gas exchange measurements demonstrated that the rate of transpiration (E) was driven by VPD, particularly under high soil moisture. Both high VPD and low soil moisture decreased photosynthesis (A) and instantaneous leaf transpiration efficiency (A/E). Increased intrinsic leaf transpiration efficiency (A/g) in response to drying soil was limited to vines growing in a non-irrigated vineyard. In this site, A/g was negatively related to vine water status. VPD did not have a substantial influence on A/g in any vineyard. While VPD is the main driver for A/E, soil moisture is an important determinant of A/g. Under high VPD, stomatal closure in Semillon leaves was not substantial enough to suitably curtail transpiration, and as a consequence A/E declined. These data indicate that in warm climates, irrigation scheduling of anisohydric varieties must take into account both VPD and soil moisture so that vine water status can be maintained.

Modelling soil water content and grapevine growth and development with the stics crop-soil model under two different water management strategies

<p style="text-align: justify;"><strong>Background and aims</strong>: Many models have been developed to evaluate crop growth and development, but few are capable of simulating grapevine systems. The present study was carried out to evaluate the ability of the STICS model to represent grapevine phenology, biomass production, yield and soil water content in two situations differing with respect to rainfall distribution and water management strategies.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Simulations were performed for an irrigated vineyard in Chile and an irrigated and a non-irrigated vineyard in France. The crop model gave a good estimation of the main stages of grapevine phenology (less than six days difference between simulated and observed values). Soil water content was the best simulated variable (R2 = 0.99), whereas grapevine evapotranspiration observed only in Chile (R2 = 0.43) and leaf area index observed only in France (R2= 0.80) were the worst simulated variables. Biomass production, yield and their components were correctly simulated (within the 95 % Student confidence interval around the mean observed value). A comparison of the fraction of transpirable soil water and vine water potential measurements with the water stress indices calculated by the STICS model showed that the time and duration of the grapevine water stress period was correctly estimated.</p><p style="text-align: justify;"><strong>Conclusions</strong>: Therefore, the STICS model was reasonably successful in simulating vine growth and development, and identifying critical periods concerning the vine water status.</p><p style="text-align: justify;"><strong>Significance of the study</strong>: The STICS model can be used to evaluate various water management strategies and their impacts on grape production.</p>

Whithin-field temporal stability of some parameters in Viticulture: potential toward a site specific management

<p style="text-align: justify;"><strong>Aims</strong>: The goal of this paper is to present the results of a study run over 7 consecutive years which aims at characterising the Temporal Stability of Within-Field Variability (TSWFV) for the most routinely measured vine parameters. In the context of precision viticulture TSWFV is of importance to know whether or not it is relevant to use the within-field variability of the year « n » to design a site-specific management strategy for the year « n+1 ».</p><p style="text-align: justify;"><strong>Methods and results</strong>: The experiment was based on 6 vine parameters measured at 30 sites located within a non-irrigated vineyard block. Parameters measured included indicators of a vine capacity to produce biomass (pruning weight, yield and size of the canopy) as well as indicators of harvest quality (sugar content, pH and Total Titrable Acidity). For each parameter a significant temporal variability of the field average was observed from one year to another. This temporal variability led us to define the TSWFV as the occurrence of consistently high value or low value zones within the field. The definition of high and low values is done according to the average field value of the year for each parameter.</p><p style="text-align: justify;"><strong>Conclusion</strong>: TSWFV analysis allows the parameters to be classified into two distinct types. Type 1 parameters (pruning weight, yield and canopy size) which present a significant TSWFV and type 2 parameters (sugar, Total Titrable Acidity and pH) which present no TSWFV.</p><p style="text-align: justify;"><strong>Significance and impact of study</strong>: For precision viticulture management these results are significant. They show that yield or vigour (pruning weight, size of the canopy) maps of the previous years are relevant in designing site-specific management strategies in the year « n+1 » or subsequent years. Conversely, maps of quality parameters from previous years are not useful in determining how to manage harvest quality in the year « n+1 ».</p>

Estimated Costs and Investment Analysis of Producing and Harvesting Muscadine Grapes in the Southeastern United States

This study estimates and compares the production costs and profitability of muscadine grape (Vitis rotundifilia) production under the single-wire (SW) and the Geneva double curtain (GDC) trellis systems with and without drip irrigation. Profitability analysis revealed that muscadine grape production can be a profitable venture. Irrigated muscadine grape vineyards were shown to be more profitable than nonirrigated vineyards. The comparison of the GDC trellis system and the SW trellis system indicates that the GDC trellis system is more profitable. Returns to land and management from muscadine grapes grown under the GDC system were found to be less sensitive to changes in prices and yields than the returns from muscadine grapes grown under the SW trellis system. Net returns from irrigated systems were also found to be less sensitive to variations in prices and yields than nonirrigated systems. The estimated total costs of establishing (Years 0–3) a muscadine grape vineyard were between $9783/acre and $15,065/acre depending on the production system used. For the GDC production system, which was the most profitable production system, the estimated return to land and management was $447/acre. Cash flow analysis demonstrated that the payback period for this system can be achieved in the 10th year, whereas the net present value of the investment was estimated at $4484 and the internal rate of return was estimated at 9.6%.

Influence of cover crop on water use and performance of vineyard in Mediterranean Portugal

Grapevine yield, vigour, fruit quality and vineyard dynamics were studied in the Estremadura Region of Portugal with a Mediterranean oceanic bioclimate. A 3-year study was carried out in a 15-year-old ‘Cabernet Sauvignon’ non-irrigated vineyard. Three treatments were compared: soil tillage (control), permanent resident vegetation, and permanent sown cover crop. The sward treatments induced changes in the weed dynamics by increasing annual and perennial grasses and perennial broad-leaved species, while annual broad-leaved species spread and persisted under a tillage system. Compared to soil tillage, the two sward treatments showed a higher water use, primarily during the spring. In the third season of the experiment, compared to cultivation treatment the two sward treatments showed a significant, favourable reduction in vine vegetative growth. The sward treatments did not affect grapevine yield or berry sugar accumulation compared to the control, but reduced must acidity and increased berry skin total phenols and anthocyanins.

The Influence ofVitis ripariaRootstock on Water Relations and Gas Exchange ofVitis viniferacv. Carignane Scion Under Non-Irrigated Conditions

A two-year study examining the water relations and gas exchange of <i>Vitis riparia</i> Michaux, <i>Vitis vinifera</i> L. cv. Carignane, and grafted vines comprised of a Carignane scion on <i>V. riparia</i> rootstock was conducted in a non-irrigated vineyard at the University of California Kearney Agricultural Center, near Fresno, California. During the two seasons the data was taken (1992 and 1993), soil water content of the trial plot was similar and decreased during the growing season. Pre-dawn leaf water potential (ψ_leaf), pre-dawn leaf osmotic potential (ψ_π), and stem water potential values (ψ_stem) did not differ among the treatments. Net carbon dioxide assimilation (A), stomatal conductance (g_s), and instantaneous water use efficiency (WUE) were influenced by treatment, and behaved similarly comparing the two years. Carignane vines had significantly greater gas exchange values than either <i>V. riparia</i> or the grafted vines, but the latter two were similar to one another. These results indicate that under non-irrigated conditions, rootstock can modify gas exchange behavior of the scion cultivar even though vine water status was not altered.

Pythium populations in Middle Eastern soils relative to different cropping practices

Population levels of Pythium spp. in soils were determined from 36 fields subjected to different cropping practices. Fungi were present in 32 of the 36 soils, in all 25 irrigated soils and in 7 of the 11 non-irrigated soils; population levels ranged from 0 to 1066 propagules g−1 d.w. The mean numbers for irrigated soils under vegetables or under citrus were higher than those for non-irrigated soils under vegetables after cereals or under vines. Twenty species and three ‘species groups’ were isolated, of all these 20 from irrigated soils under vegetables, 14 from citrus orchards, 6 from non-irrigated vineyards, and 5 from non-irrigated soils under vegetables after cereals. Pythium ‘group H.S.’, P. rostratum, P. oligandrum, and P. minor were the only taxa of Pythium common to all categories of cultivated soils.Pythium ‘group H.S.’ was the most common ‘species’; it was present in 81% of all soils and in all soils under citrus. Its highest population levels were detected in irrigated soils under vegetables. Pythium rostratum was the next commonly isolated species; mean numbers of this species were nearly similar in irrigated and non-irrigated soils. Pythium ultimum was found in 39% of all soils; it was most common (61%) in irrigated soils under vegetables, but was absent in non-irrigated soils under vegetables. Pythium oligandrum was present in 31% of all soils but was more common in non-irrigated soils than irrigated soils. Several other species were only found in irrigated soils.

Changes in soil chemical properties in a long-term fertilizer trial in a non-irrigated vineyard

Changes in soil properties in a long-term factorial experiment with nitrogen, phosphorus, and potassium fertilizer at the Nuriootpa Viticultural Research Station in South Australia were measured after 23 years of application. The measurements were related to vine yield responses reported earlier. Phosphorus, broadcast as superphosphate, gave excessively high available phosphorus levels in the top 6 in, of soil, but yield responses were delayed for 8 years until the slow-moving phosphorus reached the 6–12 in. layer where the feeder roots occurred. Broadcasting superphosphate was a wasteful and inefficient means of applying phosphorus in this environment. About three-quarters of the phosphorus applied could be measured in the top foot of soil. Nitrogen applied as sulphate of ammonia reduced pH significantly in the top 18 in. of soil, with the biggest reduction of 1.5 units to pH 5.0 in the 6–12 in. layer. As this acidity developed it probably caused the depression in vine vigour and yield. Potassium levels were high and not limiting in the unfertilized soils. The relation between nutrients supplied in the fertilizers and nutrients removed in the grapes is discussed.