Seedless Table Grape Research Articles

Changes of free and glycosidically bound monoterpenes and aromatic alcohols in Moscatuel and Ruby Seedless table grapes during development

<p style="text-align: justify;"><strong>Aims</strong>: The evolution of free and bound aromatic compounds (monoterpenes and aromatic alcohols) during ripening was determined in two cultivars of <em>Vitis vinifera</em> : Moscatuel (muscat aroma) and Ruby Seedless (neutral aroma). The aim was to identify the aromatic compounds in both varieties and to understand the differences in their aromatic characteristics.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The aromatic compounds were measured at six different maturity stages by gas chromatography and mass spectrometry. The most abundant compounds detected in Moscatuel grapes were linalool, geraniol, citronellol, nerol, citral, α-terpineol, linalool oxide I, linalool oxide II, rose oxides, benzyl alcohol and 2-phenylethanol. In general, the concentration of the main terpene compounds increased during grape development. The most abundant compounds detected in Ruby Seedless grapes were benzyl alcohol and 2-phenylethanol at concentrations higher than those observed in Moscatuel. The concentrations of the bound compounds were higher than those of the free forms, except for geraniol, nerol and citronellol in Ruby Seedless. Based on the Odour Activity Values (OAVs), linalool was the most odour-active odorant at the end of maturation in Moscatuel grapes. Other monoterpenes potentially contributing to the muscat aroma (OAV > 1) of this variety were rose oxide, citral and geraniol. In Ruby Seedless none of the studied compounds showed OAV > 1.</p><p style="text-align: justify;"><strong>Conclusion</strong>: Several differences between Moscatuel and Ruby Seedless were observed in the monoterpene and alcohol profile and their contribution to the aroma.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This study characterizes and compares two non-previously described varieties of table grape, very appreciated by consumers, with different aromatic characteristics.</p>

HPLC‐DAD‐ESI‐MS Analysis of Flavonoid Compounds in 5 Seedless Table Grapes Grown in Apulian Region

Flavonoids present in skin extracts of red seedless table grape varieties Summer Royal, Autumn Royal, and Crimson, and white seedless varieties Carati and Thompson were analyzed by HPLC-DAD-MS, in 3 y of study (2006 to 2008). The anthocyanins, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, petunidin-3-O-glucoside (with their corresponding p-coumaroyl derivatives), peonidin-3-O-glucoside, and malvidin-3-O-glucoside (with their corresponding acetyl, caffeoyl, and p-coumaroyl derivatives) were found. In addition the flavonols quercetin-3-O-glucuronide, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and the flavan-3-ols procyanidin B1, procyanidin B2, and catechin were also detected. Anthocyanins were the main flavonoids in red grapes ranging from 24 (Crimson) to 500 (Summer Royal) mg/kg fresh weight of grapes; consistent levels of flavonols and flavan-3-ols were also quantified in all varieties. To determine the effective climatic influence on flavonoids content in field conditions, viticultural practices have been developed, that could exclude the effects of direct solar radiation from confounding the assessment of those related to thermal conditions alone. A strong positive correlation was determined between flavonoids and temperature data that seem to be responsible for the difference of these metabolites along the years; furthermore, it has been possible to define a linear relationship (R(2) = 0.6871, P = 0.0057) between thermal amplitude and total flavonoids values in the red grapes. Grapes are economically the most important fruit species in the world and approximately 30% of its production is used as fresh fruit. Because of the very important role of flavonoids in food quality as well as their health-promoting properties, and considering that our experiments were performed along 3 consecutive years, gathered results in this research are quite promising to give a useful information on the flavonoid contents and their evolution in 5 seedless table grapes that are widespread in Mediterranean regions but also in California and South America, and are grown in a viticultural climate (Apulia, South Italy) very close to some regions of Spain, Turkey, Tunisia, and Israel.

Evaluation of essential oils for maintaining postharvest quality of Thompson seedless table grape

The effects of postharvest spraying of essential oils from sweet basil (Ocimum basilicum), fennel (Foeniculum vulgare), summer savory (Satureja hortensis) and thyme (Thymus vulgaris) on fungal decay and quality parameters of the ‘Thompson seedless’ table grape stored at 0 ± 1°C for 60 days were evaluated. Results showed that the essential oils, especially of thyme and fennel, have a good inhibitory effect on the development of fungal decay in Thompson table grapes. In addition, essential oils reduced weight loss, berry and rachis browning and had no considerable adverse effect on the flavour of the fruits. GC-MS analysis showed that the main compounds identified in sweet basil, fennel, summer savory and thyme oils are linalool (65.25%), trans-anethole (64.72%), carvacrol (54.14%) and β-ocimene (12.62%), respectively. Therefore, these essential oils have good potential for use as an alternative to synthetic fungicides for the preservation and storage of table grapes.

Effects of bud load on quality of Beogradska besemena and Thompson seedless table grapes and cultivar differentiation based on chemometrics of analytical indices

The effects of bud load on the quality of Beogradska besemena and Thompson seedless table grape cultivars were studied. Two pruning treatments were imposed: 44 and 18 buds per vine for Beogradska besemena and 44 and 22 buds per vine for Thompson seedless. In Beogradska besemena the reduction of bud load decreased titratable acidity (-4%), skin dry weight (-16%) and malic and citric acid contents (-43 and - 20%) and increased tartaric acid content (14%). The decrease in pulp antioxidant activity (-36%) was related to the decrease in hydroxycinnamoyl tartaric acid content (-13%). Concerning skin, the reduction of bud load decreased catechin and caffeoyl tartaric acid contents (-42 and - 40%) and significantly increased rutin and quercetin-3-O-glucopyranoside contents as specific compounds and flavonoids and proanthocyanidins (9 and 21%) as classes of compounds, thus causing an increase in antioxidant activity (6%). In Thompson seedless the reduction of bud load increased soluble solid content (7%), acidity (9%) and concentrations of the three organic acids (7, 3 and 14%). The increase in pulp antioxidant activity (25%) could be attributed to the increase in total phenolics (69%). The reduction of bud load caused a significant decrease in quercetin-3-O-glucopyranoside (-26%) and antioxidant activity (-15%) in skin. Principal component analysis allowed good separation between samples of the two cultivars, independently of bud level. The results indicate that the effects of different bud loads are cultivar-dependent. Bud load and genotype differences were shown to dramatically impact the quality and antioxidant properties of table grape.

Isolation and characterization of latent and active polyphenoloxidase in BRS Clara (CNPUV 154-147 × Centennial seedless) and BRS Morena (Marroo seedless × Centennial seedless) seedless table grapes

The seedless grapes BRS Clara and BRS Morena, developed in Brazil, are currently growing in popularity due to their premium texture and taste. However, there are no reports on the polyphenoloxidase (PPO) from these cultivars. In this paper, active and latent PPO from BRS Clara and BRS Morena seedless grapes were extracted using the non-ionic detergents Triton-X-100 (active) and Triton-X-114 (latent), and theircatecholase activities were characterized. The PPO extracted using Triton-X-110 exhibited maximum activities at pH 6.0 and at 25°C. Above 30°C, a gradual decline in activities was noted, with complete inactivation at 60°C. The PPO from grapes extracted with Triton-X-114 was activated with 0.2% of the ionic detergent sodium dodecyl sulfate (SDS), and exhibited maximum activities at pH 5.5 and at 30°C. It was stable until the temperature reached 60°C.

Phenolic Composition of the Brazilian Seedless Table Grape Varieties BRS Clara and BRS Morena

The detailed phenolic composition (anthocyanins, flavonols, hydroxycinnamic acid derivatives, stilbenes, and flavan-3-ols) in the skin and flesh of the new BRS Clara and BRS Morena seedless table grapes has been studied using HPLC-DAD-ESI-MS/MS. The two grapes, especially BRS Morena, contained high amounts of phenolic compounds, mainly located in their skins and qualitatively not different from those found in Vitis vinifera grapes. In addition, BRS Morena (a teinturier variety) showed qualitatively different phenolic compositions in its skin and flesh, mainly affecting the anthocyanin and flavonol profiles. Consistent with high phenolic contents, high antioxidant capacity values were registered for both grape varieties, especially for BRS Morena. Proanthocyanidins and hydroxycinnamoyl-tartaric acids were the major phenolic compounds found in BRS Clara and were also important in BRS Morena, although anthocyanins were the main phenolic compounds in the latter case. These results suggest that the entire grapes, including the skin, may potentially possess properties that are beneficial to human health. In this context, the BRS Morena grape can be considered as a high resveratrol producer.

Characterization of Botrytis cinerea Isolates Present in Thompson Seedless Table Grapes in the Central Valley of Chile.

Botrytis cinerea isolates from flowers and berries of Vitis vinifera 'Thompson seedless' (grapevine) were characterized in terms of two transposable elements (TEs) Boty and Flipper, random amplified polymorphic DNA (RAPD), infection levels, and resistance to iprodione. The isolates were collected from grapevines under fungicide programs of variable numbers of iprodione applications, and replicated in three Chilean Central Valley locations. Recovery was repeated from clusters collected at four phenological stages. Highest infection levels were found at bloom. Fungicide programs including one iprodione application or a combination of other fungicides were most effective for reducing gray mold symptoms. A total of 457 isolates collected from fungicide programs including only one iprodione application, and the control program, were tested for the presence of TEs. In all locations and during all phenological stages, transposa isolates (containing both TEs) were most common, followed by Boty. Vacuma isolates (containing neither TE) were identified at very low levels in two locations and only in the control treatment, and isolates with only Flipper were not detected at any time or location. Vacuma and Boty isolates were all sensitive to iprodione, while transposa isolates showed a wide range of resistance. Based on response to iprodione, the presence of TEs, and presence of vegetative-incompatibility alleles (Bc-hch), the isolates studied belong to B. cinerea Group II, a phylogenetic species within B. cinerea. Hierarchical analysis of molecular variance and genetic diversity analyses of the RAPD genotypes showed a genetic differentiation linked to location, but it was not related to geographic distance. Moreover, a genetic differentiation related to the phenological stage of grapes was also detected.

Effectiveness of Insecticides in Controlling the First and Second Generations of the Lobesia botrana (Lepidoptera: Tortricidae) in Table Grapes

The moth Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) is a key pest of table and wine grape (Vitis spp.) varieties in Cyprus. Many different insecticide combinations were applied for three consecutive years (2006-2008) in a Sultana seedless table grape vineyard, aimed at controlling the first and second generations of this pest under warm and dry Mediterranean climatic conditions. In Cyprus, Sultana is the main early maturing table grape variety grown in the country. L. botrana has two generations and a partial third on this export variety, of which the first two generations are the most destructive. Applications were made according to pheromone trap captures of males. One application was used against the first and two applications against the second generation of L. botrana. A high rate of bunch damage was observed in the untreated rows during all years, reaching 56.7, 62.5, and 69.2% in 2006, 2007, and 2008, respectively. Differences between insecticide treatments and the untreated control were statistically significant. The treatment combination of lufenuron, spinosad, and indoxacarb as well as the combination of chlorpyrifos, spinosa and indoxacarb, used against the first and second generations of L. botrana, were the most effective compared with the untreated control. Satisfactory control of the pest also was observed with other combinations such as lufenuron, cypermethrin, and Bacillus thuringiensis; chlorpyrifos, cypermethrin, and B. thuringiensis; and lufenuron, deltamethrin, and azadirachtin.

Effect of ripening on protein content and enzymatic activity of Crimson Seedless table grape

The evolution of °Brix, protein content, polyphenoloxidase activity and peroxidase activity during the ripening of Crimson Seedless table grape was studied in three consecutive years (2006, 2007 and 2008). The total protein content was determined according to Bradford’s dye binding method, and polyphenoloxidase (PPO) and peroxidase (POD) were extracted using Triton X-114 and characterised using spectrophotometric methods. The year had a statistically significant effect on all the studied parameters and there was an interannual correlation in the evolution of protein, PPO, POD and °Brix. All the studied parameters were statistically correlated, except POD activity with protein content. Weather conditions during the ripening period had a greater effect on protein content than PPO and POD activity.

Thymus kotschyanus and Carum copticum essential oils as botanical preservatives for table grape.

In the present study, essential oils extracted from Thymus kotschyanus and Carum copticumhas been evaluated for efficacy in the control of postharvest fungal decay in Thompson seedless table grape. Results showed that the tested oils exhibited good inhibitory activity against fungal decay in oil-treated grapes. In addition, the essential did not show a negative impact on the sensory quality of the grape. The profile of the oil components showed that carvacrol (28.54%) and thymol (63.18%) were the main compounds available in T. kotschyanusand C. copticum respectively. Results of this research showed that the evaluated essential oils may be used as a preservative for reduction of postharvest losses. Key words: Essential oil, table grape, Thymus kotschyanus, Carum copticum, antifungal.

TOWARDS THE DEVELOPING OF WELL ADAPTED GRAPES FOR TROPICAL REGIONS

The association between proper pruning and irrigation practices has made it possible to grow grapes (Vitis spp.) in tropical regions. Under these conditions, however, the physiological and sanitary behavior of most commercial varieties introduced from traditional temperate regions can be quite different. As a general rule, vegetative growing and yields are not stable. Besides, production costs are also higher as a result of the adoption of an intensive program of chemical interventions. The breeding program maintained by Embrapa Grape and Wine has been using Vitis genetic variability to contribute to the solution of problems resulting from lack of adaptation of traditional grape varieties. About 3,000 hybrids from crossings between several Vitis species, including wild tropical ones, are evaluated every year. Selected individuals are multiplied and evaluated on selection fields for 3-4 years. To be sure about these results, promising selections are propagated and a greater plot is evaluated for more 3-4 years. Depending on the purpose, this step can include sensorial analysis of table grapes, juice or microvinifications. Advanced selections are then tested on real yield conditions or commercial fields, for about 2 years. New cultivars are released only when this decision is also supported by growers. Usually, grape selection prerequisites are quality for processing or table, resistance to main diseases, particularly downy mildew (Plasmopara viticola) and powdery mildew (Uncinula necator), and bud fertility. The grape breeding program is using biotechnology tools as tissue culture, especially embryo rescue for the developing of seedless table grapes, and molecular markers also. In the last years, five processing cultivars ('Moscato Embrapa', 'BRS Lorena', 'BRS Rubea', 'BRS Cora' and 'BRS Violeta') and three seedless table cultivars ('BRS Morena', 'BRS Clara' and 'BRS Linda') released by the program are presenting good performance in tropical conditions. Currently, about 200 table and processing advanced selections are under evaluation.

NITROGEN FERTILIZATION ON SEEDLESS GRAPES AT THE SÃO FRANCISCO RIVER VALLEY

Aiming at determining the level of nitrogen applied through fertirrigation, appropriate for good grape plant development, better fruit quality and higher yield, an experiment was carried out in Petrolina-PE, located in the semi-arid region of the Brazilian Northeast. In a randomized blocks experimental design with split-plots were studied five seedless table grape cultivars ('Perlette', 'Thompson Seedless', 'Marroo Seedless', `Catalunha' and 'Superior Seedless') and four nitrogen levels (0, 75, 150 and 300 kg ha -1 N). Application of fertilizers was done by microsprinkler. Treatments were evaluated during two harvest seasons in 2001, one in the first and the other in the second semester. The variety 'Marroo Seedless' presented the highest yield in both yield cycles. 'Perlette' and 'Superior Seedless' also had high production at the first and second cycle, respectively. The N level of 75 kg ha -1 promoted the highest yields for 'Marroo Seedless', 'Perlette' and 'Superior Seedless' being respectively 26.4, 12.5 and 10.6 t ha -1 . The number of bunches per plant showed a direct relationship with N levels applied and yield. There was no significant effect of N levels on the other bunch characteristics evaluated.

Biochemical changes in dormant grapevine shoot tissues in response to chilling: Possible role in dormancy release

Abstract At leaf fall, one-year-old shoots of cv. Superior Seedless table grape were collected and cut into single-node sections. These cuttings were subjected to 0, 100, 200, 300, 400 or 500 h of chilling at 5 °C to simulate natural chilling accumulation. After each treatment, one group of cuttings was forced to break buds while a second group was used to study biochemical changes taking place in the bud and underlying internode tissues. Carbohydrates, free polyamines and proline concentrations were determined and amylolitic and invertase (EC 3.2.1.26) activities were estimated. Low temperature treatment caused a hydrolysis of starch concomitant with an accumulation of sucrose. There was also a rapid build-up of proline, putrescine (Put) and spermidine (Spd) which reached their maximum levels at 300 positive chill units (PCU). Afterwards, as buds approached chilling satisfaction (400 and 500 PCU), hexoses accumulated in the buds while sucrose concentration increased considerably in both structures. Proline and Put, however, decreased in both tissues. Spd level remained high, while spermine (Spm) increased slightly. Changes in starch concentration seem to be controlled by α-amylase (EC 3.2.1.1). Sucrolytic activity, consisting mainly in the acid invertase form, changed inversely to sucrose concentrations. Nevertheless, at chilling satisfaction both sucrose content and invertase activity remained high in the buds implying a possible import of sucrose into the bud which acted as a strong utilizing sink. Our data suggest that limited budbreak due to a lack of chilling may be due to low hexoses availability. However, as buds approached chilling satisfaction, a high acid invertase activity, high soluble sugars concentration and a decrease in Put to Spd plus Spm ratio appear to be correlated with bud dormancy release and improve budbreak. Furthermore, endodormancy can be divided into two phases: the first one (from 0 to 300 PCU) is an acclimation period; the second (from 300 to 500 PCU) is a beginning of growth resumption.

The powdery mildew resistance gene REN1 co-segregates with an NBS-LRR gene cluster in two Central Asian grapevines

BackgroundGrape powdery mildew is caused by the North American native pathogen Erysiphe necator. Eurasian Vitis vinifera varieties were all believed to be susceptible. REN1 is the first resistance gene naturally found in cultivated plants of Vitis vinifera.ResultsREN1 is present in 'Kishmish vatkana' and 'Dzhandzhal kara', two grapevines documented in Central Asia since the 1920's. These cultivars have a second-degree relationship (half sibs, grandparent-grandchild, or avuncular), and share by descent the chromosome on which the resistance allele REN1 is located. The REN1 interval was restricted to 1.4 cM using 38 SSR markers distributed across the locus and the segregation of the resistance phenotype in two progenies of collectively 461 offspring, derived from either resistant parent. The boundary markers delimit a 1.4-Mbp sequence in the PN40024 reference genome, which contains 27 genes with known functions, 2 full-length coiled-coil NBS-LRR genes, and 9 NBS-LRR pseudogenes. In the REN1 locus of PN40024, NBS genes have proliferated through a mixture of segmental duplications, tandem gene duplications, and intragenic recombination between paralogues, indicating that the REN1 locus has been inherently prone to producing genetic variation. Three SSR markers co-segregate with REN1, the outer ones confining the 908-kb array of NBS-LRR genes. Kinship and clustering analyses based on genetic distances with susceptible cultivars representative of Central Asian Vitis vinifera indicated that 'Kishmish vatkana' and 'Dzhandzhal kara' fit well into local germplasm. 'Kishmish vatkana' also has a parent-offspring relationship with the seedless table grape 'Sultanina'. In addition, the distant genetic relatedness to rootstocks, some of which are derived from North American species resistant to powdery mildew and have been used worldwide to guard against phylloxera since the late 1800's, argues against REN1 being infused into Vitis vinifera from a recent interspecific hybridisation.ConclusionThe REN1 gene resides in an NBS-LRR gene cluster tightly delimited by two flanking SSR markers, which can assist in the selection of this DNA block in breeding between Vitis vinifera cultivars. The REN1 locus has multiple layers of structural complexity compared with its two closely related paralogous NBS clusters, which are located some 5 Mbp upstream and 4 Mbp downstream of the REN1 interval on the same chromosome.

CLONAL SELECTION WITHIN GRAPEVINE 'ASKARI' BY MOLECULAR MARKERS

Grapevine 'Askari' is one of the important seedless table grapes in Iran. In spite of its asexual propagation, morphological markers determined differences in some accessions of this cultivar, e.g., some accessions have hard empty seeds. However, others have soft seed traces. Some of these morphological factors are useful for economical value and breeding programs. In order to evaluate these differences in genetical level, this project was designed to identify genetic variability via SSR markers within accessions named as 'Askari' cultivar. In this study 42 accessions were selected and collected from different provinces of Iran. 8 highly polymorphic SSR primers (VVS2, VVMD7, VVMD14, VVMD25, VVMD27, VVMD36, vrZAG47 and vrZAG79) were used to compare accessions. Three loci (VVS2, VVMD36 and vrZAG79) showed polymorphism. The overall results of the SSR analysis detected 5 accessions (no. 21, 31, 44, 46 and 114) which were different from others. The present study confirmed, SSR markers can be useful for identifying intra-cultivar diversity. This work requires more study to define the relation between genetical differences and some important morphological traits.

The effect of ethephon and clone on physical characteristics and sensory quality of Crimson Seedless table grapes after 1 month storage

SummaryColour is one of the most important quality parameters of table grapes. Ethephon can be applied to improve the colour of table grapes. Trials were conducted in Western Australia to investigate the effect of ethephon on low berry colour and other quality parameters of two new clones (306 and 314) of Crimson Seedless table grapes developed in Western Australia. The ethephon effect was studied in comparison with clone 5560, which was the standard clone imported from California. The grape clones were established at two locations in Western Australia having different types of soil and environmental conditions. Ethephon was applied (300 ppm Ethrel®) to improve the colour development. Physical measurements demonstrated that clones 306 and 314 were better than the imported standard clone in terms of berry weight, length and width. Sensory evaluation by 70 panellists revealed that clone 314 with ethephon application received significantly higher sensory scores for sweetness, crispness, flavour and overall acceptability compared with the standard clone. The acidity level was higher in clone 314 than the standard clone at the same °Brix level and had a positive effect on flavour and overall acceptability. Ethephon treatment reduced the berry crispness in the standard clone and clone 306 but had no effect on the crispness of clone 314.

°BRIX/ACID RATIO AS A PREDICTOR OF CONSUMER ACCEPTABILITY OF CRIMSON SEEDLESS TABLE GRAPES

ABSTRACT Harvesting at correct time is essential for the supply of quality grapes. There is no standard method to determine the proper time of harvesting for table grapes. The applicability of objective measurements such as soluble solids concentration (°Brix), acid contents (titratable acidity) and °Brix/acid ratio of Crimson Seedless table grapes were evaluated as predictors of quality in terms of consumer acceptability. Crimson Seedless table grapes were harvested from two locations in Western Australia at weekly intervals for 5 weeks. The samples were density sorted to get berries of different maturity levels. Objective measurements and sensory evaluation (panel of 63 judges) were conducted. There were significant (P ≤ 0.05) differences in the degree of liking among grapes of 16.0–17.0, 17.1–18.0 and 19.1–20.0°Brix. Consumer liking of grapes substantially changed with a change in acidity. The data revealed correlation coefficients of determination (r2) of 0.58, 0.79 and 0.85 between overall consumer acceptability and °Brix, acidity, and °Brix/acid ratio, respectively. °Brix/acid ratio was found to be the best objective measurement that reflected the consumer acceptability and can be used as a reliable tool to determine the optimum harvesting stage of Crimson Seedless table grapes.PRACTICAL APPLICATIONSCrimson Seedless table grapes have been successfully grown in Australia since 1994, and they are gaining popularity with consumers day by day. However, means of determining proper time to harvest has not yet been established. This study, by examining the relationship between instrumental measurements and human perception of sensory characteristics of Crimson Seedless table grapes, will provide a simple but reliable instrumental method to predict the optimum harvest stage of Crimson Seedless table grapes. This will help in providing a quality product to the consumers while helping growers to get better return out of their produce.

Influence of applied lysophosphatidylethanolamine on fruit quality in Thompson Seedless table grapes

Influence of applied lysophosphatidylethanolamine on fruit quality in Thompson Seedless table grapes

Pre- and post-infection activity of new fungicides against Botrytis cinérea and other fungi causing decay of table grapes

R.A. Serey, R. Torres, and B.A. Latorre. 2007. Pre- and post-infection activity of new fungicides against Botrytis cinerea and other fungi causing decay of table grapes. Cien. Inv. Agr. 34(3):215-224. Pre- and post-harvest diseases restrict table grape production and exports (Vitis vinifera L.) in Chile, with the most important disease being grey mold (Botrytis cinerea). In addition, rot due to Aspergillus niger, Cladosporium herbarum, Penicillium expansum, and Rhizopus stolonifer frequently occurs. The pre- and post-infection activity of fungicides against r these pathogens was studied on Thompson Seedless table grapes. Detached, mature, berries were used, and inoculations were performed with 20 μL of a 10 6 spores·mL -1 suspension placed on three punctures aseptically made at the calyx end of each berry. Fungicides used (per liter) were boscalid (600 mg), boscalid (200 mg) + pyraclostrobin (100 mg), boscalid (200 mg) + kresoxim methyl (100 mg), cyprodinil (60 mg) + fl udioxonil (40 mg), BAS 600 KBF (100 mg) + metrafenone (150 mg), BAS 600 KBF (200 mg) + boscalid (300 mg), BAS 600 KBF (100 mg) + pyraclostrobin (100 mg), and captan (400 mg). Each fungicide was applied either by drop (12 μL·berry -1 ) placed on three punctures made with a sterile hypodermic needle or by 60 s immersion. Berries were then incubated in humid chambers at 20oC. The pre-infection (protection) activity of the fungicides varied considerably among the pathogens tested and was found to be signifi cant (p < 0.001) and, with one exception (A. niger), it was signifi cantly (p < 0.002) affected by the application method. The interaction between fungicide and application method was only signifi cant (p < 0.001) for R. stolonifer at 48 h post treatment. In general, pre-infection activity gave 0 to 4 days protection after drop applications and 0 to 21 days after immersion treatments. The post-infection (curative) activity varied among pathogens and fungicide treatments. However, it was always below 24 h.

Identification of QTLs for Seedlessness, Berry Size, and Ripening Date in a Seedless x Seedless Table Grape Progeny

A full-sibling F1 population of 144 individuals from a cross of Ruby Seedless x Thompson Seedless (<i>Vitis vinifera</i> L.) was used to generate a consensus genetic map based on 154 markers (105 SSRs, 37 AFLPs, five ISSRs, one RAPD, four SCARs, and two phenotypic markers) distributed across 19 linkage groups covering 1,340 cM. The following traits were evaluated for later quantitative trait loci (QTL) analysis for seedlessness: number of seeds, total fresh and dry weight of seed and seed traces, berry size and weight, and ripening dates. A QTL with a major effect (K up to 45%) for seedlessness subtraits was found on linkage group 18. QTLs for berry size, berry weight, and ripening date were found in the same location, suggesting a pleiotropic effect. Seedless berries were smaller and had an earlier ripening date. Four other minor QTLs for seedless were found in linkage groups 4, 8, 15, and 16. These results are consistent with previous studies and reflect the quantitative and qualitative nature of this complex trait.