Vigorous Vine Research Articles

СОРТ ВИНОГРАДА ХОУП: ХАРАКТЕРИСТИКИ И ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ

This article presents the results of a study of a new grapevine variety called Hope, developed within the Breeding Program of the University of Arkansas, USA. The research was conducted at experimental plots of the All-Russian Research Institute of Viticulture and Winemaking – Branch of Federal State Budget Scientific Institution «FRARC». The Hope grapevine variety possesses several positive characteristics: it belongs to the seedless category of the second class, has dense flesh, and exhibits a complex and rich flavor and taste profile. The average weight of a cluster is 320 grams, while the average weight of a berry is 4.2 grams. The Hope variety has high yield potential, reaching up to 124 quintals per hectare. It shows vigorous vine growth and good resistance to diseases. Additionally, it has a good winter hardiness. Standard methodologies and vineyard cultivation techniques were used in the study. The vineyards where the research was conducted were non-irrigated and grafted, using the Oppenheim SO4 rootstock, with bilateral cordon training and a planting scheme 3×1.5 meters. The results indicated that the Hope variety has an early ripening period (requiring 118 days from bud break to full berry maturity). It has promising for use in winemaking and does not require yield regulation measures. Overall, the Hope grape variety is of interest for commercial cultivation in industrial vineyards. Its economically valuable qualities and attributes make it appealing for consumption in fresh form, wine production, and the production of dried products. It can also be included in the breeding programs of scientific institutions for further development and improvement of grape varieties.

Seedling development and juvenile growth of two yellow passion fruit genotypes as influenced by poultry manure rates

Yellow passion fruit, consumed mainly as juice in many parts of the world, is an emerging fruit crop in south-eastern Nigeria. Farmers need vigorous seedlings for optimum performance in the field. For such, a study was conducted to evaluate the effect of poultry manure (PM) rates on seedling development and juvenile growth of yellow passion fruit. Two yellow passion fruit genotypes (‘KPF-4’ and ‘Conventional’) received five poultry manure rates (0, 10, 20, 30 and 40 t/ha). The experiment was laid out as a split plot in completely randomized design and replicated thrice. The result revealed that the early seedling growth performance of the two genotypes did not statistically (P>0.05) vary. On the other hand, there was a progressive increase in the growth parameters with increasing rate of PM. Specifically, the application of 20 t/ha PM produced tallest seedlings, broadest stems and highest number of leaves in the first five weeks after PM application. However, most vigorous vines (vine length, number of leaves, fresh weights of leaves, shoots, roots) and highest accumulation of dry matter were produced by KPF-4 vines grown with 40 t/ha PM although these did not vary significantly with values recorded with 20 t/ha PM application. In view of the economics of fertilizer use, it was recommended to apply poultry manure at 20 t/ha during nursery in the study area.

Effects of intra-vineyard variability and soil heterogeneity on vine performance, dry matter and nutrient partitioning

Three vigor zones, identified in a Barbera vineyard by remote sensing at full canopy, were carefully ground-truthed to determine, over 2 years, the relative weight of soil factors in affecting within-field variability, and to investigate vigor zone influence on dry matter (DM) and nutrient partitioning into different vine organs. Regardless of season, high vigor (HV) achieved stronger vine capacity as total vegetative growth and yield while resulting in markedly less ripened fruits than low vigor (LV) vines. PCA analysis carried out on ten different soil and vine variables clearly separated the three vigor levels and the correlation matrix highlighted that the factors mostly contributing to HV were soil depth, soil K and P concentration, total available water, clay fraction and Nleaf concentration. Conversely, sand fraction was the main marker for LV. When annual DM retrieved in clusters, canes, leaves, and shoot clippings was calculated for each vigor level and expressed as content (i.e. kg/ha) there was a general decreasing trend moving from HV to LV. However, when DM partitioned to each organ was given on a relative basis (i.e. percentage over total) results were similar across vigor levels. Similarly, when nutrients were given as content (e.g. kg or g/ha) out of 120 within-vigor combinations (12 nutrients, 2 seasons, 5 organs), 65 showed a significant difference between HV and LV. Conversely, with data expressed on a concentration basis (i.e. % DM) the number of significant differences between the vigor level means fell to 15. The study strengthens the causal link between soil properties and intra-vineyard spatial variability and clarifies that patterns of dry matter and nutrient partitioning to different vine organs are mildly affected by vine vigor when referred on a relative basis.

Under-Vine Vegetation Mitigates the Impacts of Excessive Precipitation in Vineyards.

Excessive precipitation events have greatly increased in several grape growing regions due to human-caused climate change. These heavy downpours result in a myriad of problems in the vineyard including soil aggregate breakdown, soil runoff, nutrient leaching, excessive vine vegetative growth, and diseased fruit. The negative impacts of excessive precipitation events on vineyards are exacerbated by the maintenance of bare soil under the vines. Exposure of bare soil results in soil erosion and runoff which pollutes nearby watersheds; raindrops weaken and break apart soil aggregates, leading to increased soil erosivity and contributing to the formation of surface crusts. In addition to excessive precipitation events, some grape growing regions can be characterized by fertile soils. The availability of ample water and nutrients can lead to highly vigorous vines with shoot growth continuing through harvest. Long shoots and large leaves result in shaded fruit, a humid vine microclimate, and excessive cluster rot. In this review, we examined how either natural (i.e., resident) or seeded under-vine vegetation (UVV) can help mitigate many of the problems associated with excessive precipitation. Through providing vegetative coverage to reduce the force of raindrops, increasing soil organic matter and enhancing soil microbial diversity, UVV can reduce the soil degradation and off-site impacts caused by excessive precipitation events. Through competition for soil resources, UVV can reduce excessive vegetative growth of vines and decrease cluster rot incidence and severity, although grapevine response to UVV can be highly variable. We discussed recent advances in understanding below and aboveground vine response and acclimation to UVV and presented current evidence of factors influencing the impact of UVV on vine growth and productivity to assist practitioners in making informed decisions and maximize the ecosystem services provided by UVV.

Early growth and dry matter partitioning of yellow passion fruit as affected by time of application and method of poultry manure placement

Purpose Passion fruit cultivation and utilization is fast emerging in Nigeria. Poultry farms are increasing with the corresponding increase in poultry manure production which is relatively affordable by farmers. Two experiments were conducted to evaluate the effect of placement method and time of poultry manure (PM) application on early growth and dry matter partitioning of yellow passion fruit. Method PM placement methods were incorporation, top-dressing, bottom-dressing and split combination of top-and bottom-dressing while time of PM application comprised application at transplanting, 2, 4 and 6 weeks after transplanting (WAT). The experiments were laid out as completely randomized design, replicated five and six times, respectively for PM placement methods and time of PM application. Growth and dry matter yield were determined at two weeks' interval and 20 WAT, respectively. Results Longest vines (78.5 cm) were significantly (p <0.05) produced by plants that were grown in PM incorporated medium. Thickest stems (6.75 mm), highest number of leaves (66.4) and dry matter accumulation were recorded in plants that received PM as top-dressing followed by PM incorporation. Application of PM at transplanting resulted in longest vines (95.8 cm), highest number of leaves (69.5) and dry matter partitioning to leaves, vines and roots. Conclusion PM top placement performed best with respect to early growth parameters and dry matter accumulation followed by PM incorporation, hence PM top placement is recommended for production of vigorous passion fruit vines in container. Poultry manure should be applied at transplanting for vigorous vines and not delayed beyond 4 weeks after transplanting.

High potential of variable rate fertilization combined with a controlled released nitrogen form at affecting cv. Barbera vines behavior

Abstract Variable rate technologies allow site-specific management of parcels characterized by different levels of vigor and/or yield. Fertilization based on actual plant needs is one of the most promising applications of precision farming aiming at improving efficiency, optimizing vine balance, as well as limiting environmental impact. Although this strategy appears suitable for developing new vineyard management models, few experiences validating this hypothesis are available in the literature. Based on a pre-trial remotely sensed vigor map (NDVI-derived, 5 m resolution), a three-year study was performed in a Vitis vinifera L. cv. Barbera vineyard situated in the Colli Piacentini area. Vigor level (L = low, M = medium and H = high) and fertilization technique (Standard, Variable Rate Application, and unfertilized Control) were the main factors in a randomized block design. The controlled release fertilizer Multicote™ Agri ([NPK fertilizer 13-5-21 + 7MgO+14SO3 (Controlled Release Nitrogen >46% on the total nitrogen, with longevity 2÷4 months), low in chloride] was used and the input rate calculated according to the N-supply. For each vigor level the study compared no fertilization (0 kg/ha), standard supply (40 kg of N /ha) and Variable Rate Application (VRA) supply delivering 0, 40 and 80 kg of N/ha to H, M and L, respectively. Vine growth, yield, leaf nutritional status and fruit composition were assessed. Results show that the classified L vigor plots had significantly less growth (i.e leaf area or pruning weight per vine) than M and H vigor plots, whereas yield components and grape composition followed a linear variation with vigor. There was a large prevalence of vigor x technique interactions suggesting that VRA had a differential impact on vine behavior depending upon the initial level of vigor. For vegetative and yield parameters, in the L vigor vines, increased Multicote™ Agri dosage delivered as control (0 kg of N/ha), standard (40 kg of N/ha) and VRA (80 kg of N/ha) caused a very close and linear increase in total leaf and yield per vine, whereas, within the M and H vigor plots, the effect due to fertilization technique was very mild. Such a behavior was nicely mirrored by grape composition at harvest as, in L vines, applying 40 or 80 kg of N in the form of Multicote™ Agri induced a progressive and significant reduction in both must soluble solids and total anthocyanins concentration, although the oenological quality of the resulting must was still satisfactory and in compliance with the oenological target. The novelty of the present work is that, unlike previous variable rate fertilization attempts where a rapid nitrogen release fertilizer such as urea was used, L vigor vines showed a very prompt response to the amount of Multicote™ Agri application, confirming higher effectiveness of this chemical form and higher flexibility in adjusting the level of vigor and yield according to specific needs. Conversely, when the initial level of vigor was medium or high, differential fertilization resulted in overall minor modifications of the vine behavior.

Performance and Quality of Sweetpotato Cultivars Grown in Quebec, Canada with Biodegradable Plastic Mulch

There is an increased interest in producing sweetpotato (Ipomoea batatas) in parts of eastern Canada, which are farther north and have fewer growing degree days (GDD) than traditional production regions in the southern United States. There is currently little information on cultivar selection for farmers in these northern regions. We evaluated yields and quality of 15 sweetpotato cultivars and selected lines grown with black plastic mulch but without pesticides. The best marketable yields (18–25 t·ha−1) in this trial were comparable to average marketable yields obtained in traditional sweetpotato-producing regions. Of the orange-fleshed cultivars and selected lines, Beauregard, B94-24, and Evangeline had high yields and warrant further testing. Covington, a common cultivar in North Carolina and Ontario, had poor yields in our conditions: it may require more GDD. ‘Porto Rico’ and ‘Ginseng Red’ had poor yields mainly because their storage roots were too small. The yellow-fleshed ‘Georgia Jet’ and GJ2010 had very vigorous vines and produced high yields, but had a high culling rate because of malformed or cracked storage roots. The white-fleshed ‘Murasaki-29’, ‘O’Henry’, and ‘Japanese’ also had high yields; whereas ‘White Travis’ and ‘Korean Purple’ had poor yields with small storage roots. Establishing the crop with rooted transplants instead of slips was satisfactory as long as the transplants were less than 4 weeks old. On the basis of our limited data, the following cultivars and selected lines may be suitable for Quebec, Canada: Beauregard, B94-24, Evangeline, Georgia Jet, GJ2010, and Murasaki-29. ‘Evangeline’ and ‘Covington’ had higher soluble solid contents than the other cultivars. High percent soluble solids may be desired by consumers. In spite of the absence of pesticides, very few pest or disease problems were observed except for some postharvest soft rot.

Unexpected relationships between vine vigor and grape composition in warm climate conditions

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aim&lt;/strong&gt;: The purpose of the research was to link vigor with grape composition in a climate change scenario.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;: This work presents a 4-year study (from 2010 to 2013) in a non-irrigated Tempranillo vineyard located in La Rioja (Spain). It is based on the acquisition of multi-spectral imagery at &lt;em&gt;véraison&lt;/em&gt; and a subsequent zoning in two different vigor zones based on NDVI (Normalized Difference Vegetation Index). All parameters related to vigor showed significant differences within the zones (total shoot length, leaf area, pruning weight). Unexpectedly, the content in anthocyanins was found to be higher in the highest vigor zone in most of the years of study, a point particularly discussed in this work.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;: Climatic conditions may affect considerably bunch microclimate and disturb the biosynthetic pathways of major grape components, leading to maturation mismatches. In hotter years, high vigor vines may favor anthocyanin accumulation through shading and protecting effects in the bunch area.&lt;/p&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: Many studies have shown a negative relationship between vigor and grape anthocyanins, but in the present research the opposite trend was observed in hot years.

Agronomic performance of new cream to yellow-orange sweetpotato cultivars in diverse environments across South Africa

Sweetpotato is grown in diverse environments of South Africa by both commercial and subsistence farmers. The aim of the present study was to assess the stability, agronomic performance and palatability of new ARC cultivars bred for the informal market, and to make cultivar recommendations. Eight new cultivars with cream to yellow-orange flesh were evaluated in multi-environment trials using a randomised complete block design in six provinces. Data were recorded on root yield, percentage dry mass, palatability and vine vigour. An additive main effects and multiplicative interactions model was employed for data analysis. New cultivars with high potential were Ndou, Letlhabula and Monate, with root yields similar to or slightly lower than the commercial control cultivar Blesbok. Ndou and Monate had vigorous vine growth, high dry mass and good end-user acceptability and offered the best combination of important traits for the informal market. Letlhabula seemed more suitable for the commercial market owing to lower dry mass. The new improved cultivars will be advantageous, firstly, to farmers as a result of high yield and, secondly, to consumers owing to better palatibility.

Anthocyanin composition in Carignan and Grenache grapes and wines as affected by plant vigor and bunch uniformity

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aims&lt;/strong&gt;: To determine the anthocyanin composition in Carignan and Grenache grapes and wines as affected by vintage, plant vigor and bunch uniformity.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;: Anthocyanin composition of Carignan and Grenache grapes and wines were analysed by chromatographic techniques considering the influence of two different vigor levels over two vintages. The heterogeneity in the distal parts of the bunch was also taken into account. Warm vintage was better for the accumulation of anthocyanins. However, each variety responsed differently according to vine vigor. Grenache anthocyanin synthesis decreased in low vigor (weak) vines, whereas Carignan anthocyanin content depended on vigor, berry size, rootstock and vintage. In both varieties, but more significantly in Carignan, there was a tendency to accumulate acylated anthocyanins in bottom berries.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;: Carignan anthocyanin concentration was increased in low vigor plants, where clusters received greater sun exposure, unlike Grenache, where better canopy management in the fruit zone is necessary. Avoiding the poor growing conditions for Grenache in the region and improving the canopy/fruit ratio deserves careful consideration in order to reach optimal anthocyanin content.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: Knowledge of anthocyanin accumulation according to both plant vigor and bunch ripeness is of major importance to determine the optimal harvest date for each cultivar and thus improve the quality of wine.&lt;/p&gt;

In-season heat stress compromises postharvest quality and low-temperature sweetening resistance in potato (Solanum tuberosum L.)

The effects of soil temperature during tuber development on physiological processes affecting retention of postharvest quality in low-temperature sweetening (LTS) resistant and susceptible potato cultivars were investigated. 'Premier Russet' (LTS resistant), AO02183-2 (LTS resistant) and 'Ranger Russet' (LTS susceptible) tubers were grown at 16 (ambient), 23 and 29 °C during bulking (111-164 DAP) and maturation (151-180 DAP). Bulking at 29 °C virtually eliminated yield despite vigorous vine growth. Tuber specific gravity decreased as soil temperature increased during bulking, but was not affected by temperature during maturation. Bulking at 23 °C and maturation at 29 °C induced higher reducing sugar levels in the proximal (basal) ends of tubers, resulting in non-uniform fry color at harvest, and abolished the LTS-resistant phenotype of 'Premier Russet' tubers. AO02183-2 tubers were more tolerant of heat for retention of LTS resistance. Higher bulking and maturation temperatures also accelerated LTS and loss of process quality of 'Ranger Russet' tubers, consistent with increased invertase and lower invertase inhibitor activities. During LTS, tuber respiration fell rapidly to a minimum as temperature decreased from 9 to 4 °C, followed by an increase to a maximum as tubers acclimated to 4 °C; respiration then declined over the remaining storage period. The magnitude of this cold-induced acclimation response correlated directly with the extent of buildup in sugars over the 24-day LTS period and thus reflected the effects of in-season heat stress on propensity of tubers to sweeten and lose process quality at 4 °C. While morphologically indistinguishable from control tubers, tubers grown at elevated temperature had different basal metabolic (respiration) rates at harvest and during cold acclimation, reduced dormancy during storage, greater increases in sucrose and reducing sugars and associated loss of process quality during LTS, and reduced ability to improve process quality through reconditioning. Breeding for retention of postharvest quality and LTS resistance should consider strategies for incorporating more robust tolerance to in-season heat stress.

Role of Canopy Management in Controlling High pH in Tannat Grapes and Wines

Elevated wine pH is one of the main problems affecting the quality of <i>Vitis vinifera</i> L. Tannat wines in Uruguay. High soil fertility, promoting vigorous vines, and high potassium availability result in high pH grapes and wine. The main objective of this work was to determine the effects of partial leaf and lateral shoot removal practices on the reduction of juice and wine pH over three growing seasons. Partial defoliation in shaded canopies significantly reduced grape potassium accumulation, malic to tartaric acid ratio, and wine pH without negatively affecting other quality parameters of soluble solids, organic acids, anthocyanins, and phenolics.

Powdery mildew development is positively influenced by grapevine vegetative growth induced by different soil management strategies

In various crop species, high levels of powdery mildew infection and severity have been associated with high vegetative vigour. In grapevine this relationship has also been observed by vine growers, though it has not been quantified. This study was undertaken to investigate the relationship between the development of powdery mildew on leaves and berries and canopy growth, and thus to quantify the relationship between the pathogen and its host. Over a two-year period (2005 and 2006), an experiment was carried out in a vineyard (cv. Aranel) near Montpellier, southern France. Several levels of canopy growth were generated by implementing four soil management strategies: i) perennial cover crop in the inter-row, ii) annual cover crop in the inter-row, iii) chemical weed control over the entire soil surface, iv) chemical weed control all over the soil surface and drip irrigation and fertilization in the row. Powdery mildew was artificially inoculated on experimental sub-plots with Erysiphe necator [Schw.] Burr. conidia. The most vigorous vines developed a larger number of diseased leaves and a higher percentage of mildewed berries compared to low-vigour vines. The major explanatory variable highlighted in these experiments was the shoot leaf number, mainly early in the season. A higher leaf population generated a larger number of powdery mildew colonies close to grapes and consequently a higher probability of berry infection. Our experimental results provide evidence of a positive relationship between powdery mildew development and grapevine vegetative development. These results provide an opportunity to develop new IPM strategies in vineyards.

Relation between Seed Appearance and Phenolic Maturity: A Case Study Using Grapes cv. Carménère

Sensory evaluation of grapes (Vitis vinifera L.) plays a key role in determining the harvest time in grapevine varieties. The harvest time of cv. Carmenere is one of the latest of Chile. During the season 2007-2008, the evolution of the appearance of Carmenere seeds was evaluated as a harvest criterion, comparing it with the chemical and phenolic ripening. The samples were obtained from an organic vineyard located in Curico Valley, Chile. Starting at 16 oBrix, 100 seed berries samples were collected weekly from medium vigor vines in order to register photographically the ventral and dorsal sides of each seed. In addition to the seed tannins percentage, the extractable anthocyanins, total anthocyanins and total polyphenols index, as well as the titratable acidity, soluble solids and pH were registered. A color wheel of seed coat with a description of 12 digital colors was proposed for this cultivar. When the color number exceeded 10 (very dark brown), the soluble solids had already reached 24 oBrix 1 month earlier. Two inverse correlations between seed coat color vs. seed phenols percentage and vs. total polyphenol index were found. The proper phenolic maturation (maximum anthocyanins and minimum seed tannins percentage) occurred 177 d post flowering. The observation of seed coat color can be a reliable, simple and low-cost parameter to determine the correct ripeness of phenols in ‘Carmenere’ grapevines.

Effect of Potato Virus Y on Yield of a Clonal Selection of Russet Norkotah

Successful selections of Russet Norkotah lines have produced larger, more vigorous vines and higher yields than the standard Russet Norkotah (RN). Potato Virus Y (PVY), while producing mild or “latent” symptoms in this cultivar, has been shown to significantly reduce yields. To determine PVY’s effect on yield of a RN selection, PVY infected RN and Russet Norkotah selection 3 (RN3) yields were compared after planting in Hermiston, Oregon in 2001, 2003, and 2006. After emergence, individual plants were ELISA tested for PVY multiple times during the growing season to confirm infection. Plants were categorized when infected; 1) current season, 2) seed borne or 3) “no PVY”. At harvest, total and marketable yield data were collected. RN3 produced higher total yields than RN, regardless of infection categories. Highest yield reductions of RN and RN3 due to PVY were in the following order; seed borne PVY >>current season PVY >>no PVY.

Influence of plot characteristics and surrounding vegetation on the intra‐plot spatial distribution of Empoasca vitis

Abstract Spatial distributions of adults and nymphs of Empoasca vitis were assessed during 3 years inside two adjacent vine plots having considerable intra‐plot variability, diversified natural ground cover and surrounding vegetation, and no insecticide application. Geostatistical analysis confirmed that, in spite of repeated adult migrations, spatial distributions of summer populations were highly aggregated, similar every year and similar between adults and nymphs. Comparison of insect distribution with intra‐plot characteristics, such as vine plant vigour (leaf density and leaf chlorophyll concentration) and phenology, plot topography and surrounding vegetation, revealed that E. vitis clearly aggregates in areas with the most vigorous vine plants. Even though the presence of natural enemies in the surrounding vegetation was confirmed by specific observations, we did not observe significant population decrease at the contiguous plot edges. Natural ground cover, together with the absence of insecticide, might allow the spreading and perennial conservation of E. vitis natural enemies inside the plots. Clear adult aggregations observed along downwind woodlands suggest that this vegetation acts as a barrier and intercepts the adults flying passively across the plot. However, this surrounding vegetation could also serve as an alternative refuge when vine water deficit and vine foliage temperature increase.

Kalkaska: A Round White Chip-Processing Potato Variety with Common Scab Resistance

Kalkaska is a high yielding, round white potato with an attractive appearance with shallow eyes. Kalkaska has a vigorous vine and a late maturity. This variety has resistance to Streptomyces scabies Thaxter (common scab of potato) similar to Pike. Kalkaska has industry approved chip-processing storage characteristics (light color and low incidence of defects) and it also has better tolerance to blackspot bruise than Snowden. Specific gravity in Michigan averages 1.083, ranging from 1.075 to 1.096. Kalkaska also has a higher marketable yield than Pike and does not express heat necrosis in the tubers. The name Kalkaska was chosen to acknowledge a town located in the Michigan seed growing region.

Grey mould incidence is reduced on grapevines with lower vegetative and reproductive growth

The hypothesis that grey mould incidence would be positively correlated to grapevine canopy development was confirmed over a period of 3 years (2004–2006) on Aranel cultivar in an experimental vineyard near Montpellier, south France. Different levels of vine growth were generated by implementing three management schemes: (i) perennial cover crop, (ii) chemical weed control and (iii) irrigation and fertilisation. Grey mould incidence was assessed at harvest, together with various sets of variables linked with canopy microclimate, shoot vigour, vine capacity, cluster architecture, yield components and fruit composition. Significant positive correlations were observed between disease incidence and key variables of shoot vigour and vine capacity: total leaf number, leaf dry matter, leaf layer number, leaf area per metre of row, pruning mass and nitrogen accumulation. In 2004, Botrytis cinerea developed in all experimental plots because climatic and microclimatic conditions were conducive to grey mould. The climatic and microclimatic variables that significantly favoured grey mould development were: precipitation, duration of relative humidity >90% in the canopy and low potential evapotranspiration. However, in 2005 and 2006, under dry summer conditions, disease developed only in the most vigorous vines, which were both irrigated and fertilised. These vines showed a very high canopy growth, very compact clusters and a delayed fruit maturity. This evidenced that unfavourable climatic conditions for the disease development can be counterbalanced by conditions of high vine growth and associated canopy and cluster features.

Effect of Shading on Accumulation of Flavonoid Compounds in (Vitis vinifera L.) Pinot Noir Fruit and Extraction in a Model System

Accumulation and compositional changes of flavonols, proanthocyanidins, and anthocyanins were measured in Vitis vinifera L. cv. Pinot noir in shaded and exposed treatments. In addition, extraction of these compounds into a model wine solution was measured. The study was conducted in a commercial vineyard within a uniform zone of relatively low vigor vines. Light exclusion boxes were installed on pairs of clusters on the same shoot (shaded treatment), and a second set of clusters on an adjacent shoot were labeled as the exposed treatment. Fruit samples were harvested at the onset of ripening (véraison) and at commercial harvest. Cluster shading resulted in a substantial decrease in mg/berry accumulation of flavonols and skin proanthocyanidins and minimal differences in anthocyanins. In analyzing seed proanthocyanidins by phloroglucinolysis, shaded and exposed treatments were similar at véraison; however, by harvest, the shaded treatment had higher extension and terminal subunits (nmol/seed) as compared to the exposed treatment. For skin proanthocyanidins, shaded fruit was lower for all subunits (nmol/berry) at both véraison and harvest. Shading caused an increase in the proportion of (-)-epicatechin and a decrease in (-)-epigallocatechin at harvest in skin extension subunits. Seed proanthocyanidins in shaded fruit contained a lower proportion of (+)-catechin and a higher proportion of (-)-epicatechin-3-O-gallate in extension subunits and a lower proportion of (+)-catechin and (-)-epicatechin-3-O-gallate and a higher proportion of (-)-epicatechin in terminal subunits. For anthocyanins, the shaded treatment had a proportional reduction in delphinidin, cyanidin, petunidin, and malvidin and a large increase in peonidin glucosides. The model extractions from the two treatments paralleled differences in the fruit with a lower concentration of flavonols, anthocyanins, and proanthocyanidins in the shaded treatment. The skin proanthocyanidin percent extraction was found to be approximately 17% higher in the exposed model extraction than the shaded treatment.

Drip Irrigation Effect on Yield and Fruit Size of Jack-o-lantern Pumpkins

Benefits of drip irrigation for jack-o-lantern pumpkins (Cucurbita pepo) in the midwestern United States are not documented. Field trials were conducted on a sandy loam soil to compare yield and fruit size of unirrigated pumpkins (NONE) with pumpkins irrigated when in-row soil water tension (SWT) 30 cm deep reached 20 kPa (HIGH) or 60 kPa (MED). The 2004 trial included two planting methods, direct seed (SD) and transplant, and two cultivars, `Gold Medal' (GM) and `Magic Lantern' (ML). GM typically has larger and more vigorous vines than ML. In 2005 the trial included only SD ML. Rainfall June through August totaled 38.4 cm in 2004 and 28.2 cm in 2005. In 2004 HIGH increased yield 13% compared to NONE (42.1 vs. 37.2 t·ha-1). MED (39.0 t·ha-1) did not differ from NONE. Neither planting method nor cultivar influenced the yield response to irrigation. The effect of irrigation on average weight per pumpkin depended on cultivar. In 2004, ML with HIGH averaged 7.76 kg per pumpkin, 16% heavier than NONE at 6.67 kg. MED averaged 7.17 kg. Irrigation did not affect average weight of GM: HIGH, MED and NONE averaged 12.6, 12.8 and 12.3 kg, respectively. For SD ML, combined analysis of 2004 and 2005 data showed an 18% increase in average pumpkin weight for HIGH vs. NONE (7.94 vs. 6.72 kg), but no significant effect of irrigation on yield (33.6, 29.8 and 28.4 t·ha-1 for HIGH, MED and NONE, respectively). Irrigation did not affect the number of pumpkins produced per hectare for either cultivar in either year. Results suggest that compared to no irrigation, maintaining SWT less than 20 kPA with drip irrigation may lead to 1) yield increase on the order of 10% or less, 2) 16% to 18% increase in average pumpkin weight for ML.