Effect of aminoethoxyvinylglycine (AVG) on quality, berry set and coloration of ‘Alphonse Lavallée’ table grapes

The effect of different concentrations of aminoethoxyvinylglycine (AVG; 0 (control), 250, 500, 750 and 1000 mg/l), an ethylene biosynthesis inhibitor, on grape berry set and fruit quality was evaluated under vineyard conditions. Treatments were performed on ‘Alphonse Lavallée’ grape cultivar at full bloom stage for two years. Cluster and berry growth (length, width and weight), firmness, soluble solids content, yield, berry set, anthocyanin content and colour parameters were determined on treated and untreated (control) fruits. As a result of the study, the effects of AVG concentrations on firmness were not significant. When AVG applications were compared with control, it is determined that some quality properties were statistically affected, the others were not. Fruit set was increased by lower concentrations of AVG (250 mg/l) and anthocyanin content was increased by higher concentrations of AVG (750 mg/l).

Early water stress effects on pollen viability, berry set and embryo development in cv. ‘Syrah’ (Vitis vinifera L.)

Early water deficit at bloom results in poor berry set and/or a grape yield reduction. The purpose of this work was to determine the effects of early water stress in a berry’s development. The experiment was carried out in a SupAgro ECOTRON System in Montpellier, France. Seven year- old ‘Syrah’ vines were used. The pot’s surface was protected from rainfall, and the growing medium was perlite+coarse sand with controlled drainage. The treatments were WS₀ (control): 4 l/day, WS₁: 3 l/day, WS₂: 2 l/day, and WS₃: 1 l/day. The water deficit was carried out from the 17^th to the 27^th Eichhorn-Lorenz (E-L) stages. In order to emphasise details of the embryo development, a paraffin section method and technique was used. With the early water stress, there was no effect on the pollen viability and pollen germination ratios. The berry set ratio was reduced and the berry development were affected negatively by the early water stress. Between the 19^th and the 27^th E-L stages, an early water stress in ‘Syrah’ was noted, with decreases in the pre-dawn leaf water potential values below –0.8 MPa. The water deficit affected the berry growth and the development negatively.

Using common viticultural practices to modulate the rotundone and 3-isobutyl-2-methoxypyrazine composition of Vitis vinifera L. cv. Fer N red wines from a temperate climate wine region with very cool nights

Aim: Rotundone and 3-isobutyl-2-methoxypyrazine (IBMP) are two potent aroma compounds responsible for pepper and bell pepper notes in red wines, respectively. The aim of the study was to modulate, through common viticultural practices, the volatile composition in these two molecules of Fer red wines from a temperate climate wine region with very cool nights, located in the southwest of France.Methods and results: Three viticultural practices (leaf removal 10 days after berry set, removal of lateral shoots, and delayed harvest 7 days after the control) were investigated in 2015 and in 2016. Rotundone concentrations up to 69 ng/L were found in experimental wines. IBMP concentrations were below perception level in wines from 2016 and below detection level in wines from 2015, a vintage with particularly hot climatic conditions between berry set and bunch closure. Delayed harvest induced an increase in rotundone concentration while leaf removal and the removal of lateral shoots had no significant impact on rotundone concentration. Delayed harvest and the removal of lateral shoots were the most efficient practices to decrease IBMP in wines. The three techniques made it possible to increase the odour activity values (OAV) ratio of OAV rotundone to OAV IBMP, with the greatest impact observed for delayed harvest.Conclusion: According to our results, delayed harvest appears to be the best practice to modulate the volatile composition of Fer wines toward an increase in the OAV rotundone to OAV IBMP ratio.Significance and impact of the study: Our results may assist local grape growers to modulate the volatile composition of their wines.

Defoliation of the vines before or after berry set: Physiological consequences and qualitative factors

Defoliation of the vines consists of eliminating the leaves in the grape bunch zone in a more or less intensive manner. It is a long-proven prophylactic technique that has seen a renewed interest in the current context of the reduction of phytosanitary inputs. However, several questions remain. Which is the optimal period? What is the ideal intensity? What are the risks? Is the mechanization of this process a feasible option? Agroscope has been undertaking defoliation trials in Switzerland since 2010 in order to shed light on these questions.

Инструментальные методы выявления хлороза виноградной лозы в Крыму

Проблема хлороза винограда является актуальной для почвенно-агроэкологических условий Крыма. Проведена оценка развития хлороза двумя новыми инструментальными методами в сравнении с традиционным визуальным осмотром. Показано, что хлороз винограда в фазу начала образования ягоды хорошо идентифицируется с помощью определения вегетационного индекса NDVI прибором GreenSeeker Handheld, а также методом автоматического распознавания фотоизображений листьев в видимом диапазоне спектра. Данные методы можно применять в автоматическом режиме для выборочной обработки растений хелатными формами железа по листу.Grapevine chlorosis is a matter of pressing concern in the soil-agroecological conditions of Crimea. Two new instrumental methods for chlorosis detection were tested and compared to traditional visual inspection. It was demonstrated that grapevine chlorosis at the berry set formation stage is easily identified by NDVI vegetation index identification using GreenSeeker Handheld device, as well as by leaf photographic images automatic recognition in the visible range of the spectrum. These methods can be used in automatic regime for the identification of chlorosis, and selective foliar treatment with ferric chelates.

Combined influence of bud load and bud position along the cane on vegetative and reproductive parameters of grape cv. Grillo

Cultivar Grillo vines are characterized by problems with flower biology (the fertility of basal buds) and fructification (millerandage). In this study, to manage the variability in bunch weight with winter pruning and to program others canopy management practices (i.e. early defoliation), three different treatments of bud load were set up by leaving the cane with 3, 6 or 10 buds. The effects of bud load and cane length were studies regarding bud fertility, shoot leaf area, and the number of flowers and berries, as well as the relationship between leaf area and percentage of fruit set, leaf area/flower and percentage of fruit set, and the number of hens and chicks berries. Shoots in the distal position had higher values of fertility and inflorescences with a greater number of flowers, while no ‘apical’ effect of the buds emerged. A good relationship was found between fruit set and the number of flowers, leaf area at flowering and yield, and square centimeters/flower and percentage of fruit set. Cane length was found to be a valid tool for managing bunch weight variability; the value of the leaf area/flower can be used to program early defoliation practice carried out to manage berry set.

Effects of post-bloom low light and girdling on fruit set of Vitis vinifera (L.) cv. ‘Riesling’ and Vitis labruscana (L.) cv. ‘Concord’

Aim: In grapevines, similarly to many woody crops, berry set is a crucial determinant for vine productivity. We reduced vine carbohydrate supply through shading and preventing phloem flow by girdling to investigate the effects on fruit set and berry weight, in field-grown ‘Concord’ (Vitis labruscana L.) and ‘Riesling’ (Vitis vinifera L.) grapevines.Methods and results: Carbon supply to the fruit was manipulated by shading (30% light transmissivity) individual shoots or shading and girdling. Girdling isolated the shoot and its fruit from possible carbohydrate supply from the rest of the vine. Shading was accomplished by covering shoots with a woven strip of shade cloth for four consecutive days in the period between flowering and 28 (‘Concord’) or 16 (‘Riesling’) days after flowering. The percentage of fruit set was calculated from estimated flower numbers using a photographic method and actual berry counts.Conclusions: In both ‘Concord’ and ‘Riesling’, short-time shading caused reductions in fruit set, although this effect was more severe in ‘Concord’. Both species were most sensitive to reductions in carbon supply during the period between 5 and 12 days after flowering. In ‘Concord’ vines, the effects caused by shading were greater with girdling probably because ‘Concord’ vines had higher crop level. Significance and impact of the study: The results can be used as basis for modelling fruit set in grapevines.