الفهرس 
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Abstract
This study was carried out during 2007 and 2008 seasons on 5 years old Red Globe grapevines grown in a private vineyard namely Medhat El-Kaissy located at Bardanoha village, Mattay district, Minia Governorate. The texture of the vineyard soil is clay and the selected vines are spaced at 1.5 × 3 m apart . The vines were trained in the first week of Jan. in both seasons using cordonic method with susing Gable supporting system . Vine load was 48 eyes (12 fruiting spurs × 3 eyes plus 6 replacement spurs × 2 eyes).
This study aimed to throw some light on the effect of single or combined application of the two antioxidants namely citric and ascorbic acids in addition to boron on behaviour of buds , some vegetative growth characters, berry set % , yield , cluster weight and fruit quality of Red Globe grapevines .
The present experiment included the following twelve treatments from the two antioxidants (citric and ascorbic acids) and boron :-
1- Control (untreated vines).
2- Spraying ascorbic acid at 250 ppm (0.25 g / L)
3- Spraying ascorbic acid at 500 ppm (0.5 g / L)
4- Spraying ascorbic acid at 1000 ppm (1.0 g / L)
5- Spraying citric acid at 500 ppm (0.5 g / L)
6- Spraying acitric acid at 1000 ppm (1.0 g / L)
7- Spraying boric acid at 0.0125% (0.125 g / L)
8- Spraying ascorbic acid at 250 ppm + boric acid at 0.0125%
9- Spraying ascorbic acid at 500 ppm + boric acid at 0.0125%
10- Spraying ascorbic acid at 1000 ppm + boric acid at 0.0125%
11- Spraying citric acid at 500 ppm + boric acid at 0.0125%.
12- Spraying citric acid at 1000 ppm + boric acid at 0.0125%.
Each treatment was replicated four times, one vine per each .The control treatment was sprayed with water containing wetting agent .The two antioxidants and boric acid (17 % B) were sprayed three times during the growing season of 2007 and 2008 . The first date was at growth start (middle of April), just after berry setting ( first week of June) and at 21 days later (last week of June). New film at 0.05% (0.5cm / L) as a wetting agent was added to all spraying solutions. Spraying was done till runoff. Boron in the source of boric acid was sprayed at the recommended concentration .The experiment was set up in completely randomized block design.
In both seasons, the following parameters were measured :-
1- Percentages of bud burst and fruiting buds.
2- Vegetative growth characters namely main shoot length (cm), number of leaves and laterals per main shoot, leaf area (cm2) and cane thickness (cm.)
3- Percentage of berry setting.
4- Yield / vine expressed in weight (kg.) and number of clusters per vine .
5- Cluster characters namely weight (g.), width and length (cm.) .
6- Physical and chemical characters of the berries namely weight (g.) longitudinal and equatorial of berry (cm.), total soluble solids % , total sugars % as well as the ratio between T.S.S and acid and total acidity (a g tartaric acid per 100ml juice .
The obtained data in both seasons could be summarized under the following main items:
1- Behavious of buds :-
Single or combined application of ascorbic acid at 250 to 1000 ppm, citric acid at 500 to 1000 ppm and boric acid at 0.0125% caused a considerable stimulation on percentages of bud burst and fruiting buds compared to the control treatment. Spraying boric acid , citric acid and ascorbic acid, in descending order was favourable in enhancing bud burst and fruiting buds. Increasing concentrations of both the two antioxidants was followed by a gradual stimulation. Combined application of any one of the two antioxidants with boric acid caused a striking stimulation compared to using each material alone . The maximum values were recorded on the vines treated with citric acid at 1000 ppm plus boric acid at 0.0125% . Untreated vines produced the minimum values.
2- Vegetative growth characters :-
The five vegetative growth characters namely main shoot length, number of leaves per shoot, number of laterals / shoot, leaf area and cane thickness were greatly stimulated in response to single or combined application of ascorbic acid , citric acid and boric acid compared to the control treatment. The stimulation on growth traits was associated with increasing concentrations of the two antioxidants and application of boric acid , citric acid and ascorbic acid , in descending order. Increasing concentrations of each antioxidant from 500 to 1000 ppm failed to show measurable increase on such growth characters . Combined application of each antioxidant with boric acid was favourable for enhancing such growth characters than using each alone. The highest values were recorded when the vines received three sprays of citric acid at 1000 ppm and boric acid at 0.0125% . Untreated vines produced the minimum values .
3- Percentage of berry set, yield and cluster characters.
Treating Red Globe grapevines three times with ascorbic acid at 250 to 1000 ppm , citric acid at 500 to 1000 ppm and boric acid at 0.0125% either applied singly or in different combinations was very effective in enhancing berry set %, yield expressed in weight and number of clusters per vine and weight , length and width of cluster compared to the check treatment. The promotion was associated with increasing concentrations of each antioxidant. Negligible promotion on these parameters was observed among the two highest concentration from each antioxidant. The highest values were detected on the vines treated with boric acid , citric acid and Ascorbic acid , in descending order. The greatest values were detected on the vines treated three times with citric acid at 500 ppm plus boric acid at 0.0125% from economical point of view . The lowest values were recorded on untreated vines.
4- Physical and chemical characters of the berries :-
Single or combined application of the two antioxidants namely ascorbic acid at 250 to 1000 ppm , citric acid at 500 to 1000 ppm and boric acid at 0.0125% was accompanied with improving quality of the berries in terms of increasing berry weight and dimensions ( longitudinal and equatorial ) , total soluble solids % , total sugars and T.S.S / acid and decreasing total acidity rather than the check treatment . The promotion was associated with increasing concentrations of each antioxidant. Application of boric acid was superior the application of the two antioxidants. Spraying citric acid was preferable than using ascorbic acid in this respect . Fruit quality did not change largely with increasing concentrations of each antioxidant from 500 to 1000 ppm. Therefore, the suggested concentration from each antioxidant responsible for improving fruit quality was 500 ppm . The best results with regard to physical and chemical characters of the berries were obtained when the vines sprayed three times with citric acid at 500 ppm plus boric acid at 0.0125%. Untreating the vines gave unacceptable effect on quality of the berries .