الفهرس 
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Abstract
This study was carried out during 2006/2007 and 2007/2008 seasons on Superior grapevines grown in a private vineyard located at Qeft district, Qena Governorate where the soil texture is sandy. The selected vines are spaced at 2 x3 meters apart.
The goal of this investigation was studying the effects of different concentrations and dates of application of Dormex as well as the antioxidant citric acid, magnesium, boron and iron on the behaviour of buds, some vegetative growth characters, leaf chemical composition, yield as well as physical and chemical characters of Superior grapes.
The vines were pruned just before Dormex application on the last week of Dec. in 2006/ 2007 and 2007/ 2008 seasons. The selected vines were subjected to cane pruning system leaving 6 fruiting canes x ten eyes plus six renewal spurs x two eyes with a total vine load reached 72 eyes per vine. Baron supporting system was followed .
The present experiment involved thirty – two treatments from three factors ( A & B & C). They arranged as follows : The first factor (A) consisted of four concentrations of Dormex (breaking agent material containing 49% Hydrogen cyanamide) namely a1) 0.0%, a2) 1.0% , a3) 2% and a4) 4%. The second factor (B) contained the following four dates of Dormex application :
b1) Spraying Dormex on the last week of Dec. (when the vines exposed to 75 chilling hours)
b2) Spraying Dormex on the first week of Jan. (when the vines exposed to 90 chilling hours)
b3) Spraying Dormex on the second week of Jan. (when the vines exposed to 110 chilling hours)
b4) Spraying Dormex on the third week of Jan. (when the vines exposed to 130 chilling hours)
The third factor (C) consisted of two treatments of the antioxidant citric acid, magnesium, boron and iron namely C1) 0.0% (unreated vines) and C2) Spraying citric acid at 0.025% + magnesium sulphate at 0.1 % + boric acid at 0.0125 % + chelated iron at 0.05 % . Each treatment was replicated three times, two vines per each.
Both citric acid and the three nutrients were sprayed four times during each seasons at growth start ( 1st week of Mar.) , just after berry setting (1st week of April) and at 14 days intervals (3rd of April and 2nd week of May)
The present experiment was set up in a complete randomized bock design in a split- split- plot arrangement with three replicates each consisted of two Superior seedless grapevines. The experiment included three factors ( A & B & C). The four concentrations of Dormex ( 0.0, 1.0 , 2.0 and 4.0 %) (Factor A) were arranged in the main plots, whereas the four spraying dates of Dormex ( last week of Dec. as well as 1st , 2nd and 3rd week of Jan.) (Factor B) occupied the sub- plots. The third factor (C) where included two treatments of citric acid , magnesium, boron and iron treatments ranked the sub sub- plots.
The following measurements were recorded during the two experimental seasons.
1-Date of bud burst as well as percentages of bud burst and fruiting buds.
2- Some vegetative growth characters namely main shoot length (cm.), number of leaves per main shoot, leaf area (cm2) cane thickness (cm.) and weight of pruning wood (kg.)
3- Percentages of N, P, K , Mg and Fe in the leaves .
4- Percentage of berry setting.
5-Harvesting date.
6-Yield per vine expressed in weight (kg.) and number of clusters per vine and cluster weight (g.)
7- Percentage of shot berries
8- Some physical characters of the grapes namely berry weight (g.) and dimensions (longitudinal and equatorial in cm.),and berry index.
9-Some chemical characters of the grapes namely total soluble solids%, total acidity %, total sugars % and total soluble solids / acid.
The nearly same obtained data in both seasons could be summarized under the following main items:
1-Behaviour of buds:
Percentage of fruiting buds did not affect by Dormex, citric acid and nutrient treatments in the first season of the study. Spraying Dormex at 1.0 to 4.0 % was very effective in advancing bud break and enhancing percentages of bud break and fruiting buds compared to the check treatment. The advancement on bud break and the promotion on percentages of bud burst and fruiting buds were associated with increasing Dormex concentrations. Negligable promotion was detected among the higher two concentrations of Dormex.
Spraying Dormex on the second week of Jan., the first week of Jan., the third week of Jan. and the last week of Dec. in descending order gave an early bud break and maximum percentages of bud break and fruiting buds.
Combined application of the antioxidant citric acid at 0.025%, magnesium sulphate at 0.1% , boric acid at 0.0125 % and chelated Fe at 0.05% was very effective in enhancing bud break and percentages of bud break and fruiting buds rather than non- application.
An obvious hastening on bud break and maximum percentages of bud burst and fruiting buds were recorded on the vines sprayed with Dormex at 4% on the second week of Jan. when the vines exposed to 110 C.H. plus citric acid, magnesium, boron and iron.
2- Some vegetative growth characters:
The five growth characters namely main shoot length , number of leaves per main shoot, leaf area, cane thickness and weight of pruning wood were positively affected by application of Dormex at 1.0 to 4.0 % compared to the check treatment. There was a gradual promotion on these growth aspects with increasing Dormex concentrations. Increasing Dormex concentrations from 2.0 to 4.0 % failed to show measurable promotion on these traits.
In descending order, the great stimulation on these vegetative growth characters was attributed to using Dormex on the second week of Jan. , the first week of Jan., the third week of Jan. and the last week of Dec. when the vines exposed to 110 , 90, 130 and 75 C.H., respectively. The maximum values were recorded when the vines sprayed with Dormex on the second week of Jan. and when the vines exposed to 110 C.H.
Treating the vines with citric acid, magnesium , boron and iron was considerably followed by stimulating all growth characters rather than non- application.
Spraying the vines on the second week of Jan. with Dormex at 4% plus supplying the vines with citric acid, magnesium, boron and iron effectively maximized these growth characters.
3-Percentages of N, P, K, Mg and Fe in the leaves:
Percentages of N, P, K, Mg and Fe were gradually increased with increasing Dormex concentrations from 0.0 to 4.0 %. Increasing concentrations of Dormex from 2.0 to 4.0 % had no measurable promotion on these nutrients. The maximum values were recorded on the vines sprayed with Dormex at 4.0% .
The maximum values of these nutrients were presented in the vines treated with Dormex in the second week of Jan., first week of Jan. third week of Jan. and last week of Dec. in descending order.
Supplying the vines with citric acid, magnesium, boron and iron together resulted in the maximum values of these nutrients rather than the control treatment.
Treating the vines with Dormex at 4% on the second week of Jan. plus spraying of citric acid, magnesium, boron and iron effectively maximized percentages of N, P, K, Mg and Fe in the leaves.
4- Percentage of berry setting , yield and cluster weight.
Number of clusters per vine did not affect with Dormex, antioxidant and nutrient treatments in the first season of study. Using Dormex at 1.0 to 4.0% was responsible for improving berry setting % , yield expressed in weight and number of clusters per vine and cluster weight rather than non application. The promotion was associated with increasing Dormex concentrations. Negligable stimulation was observed on these criteria among the higher two concentrations namely 2.0 and 4.0 % . Therefore, for economically point of view, it is suggested for using Dormex at 2.0 % .
Selecting the best date for application of Dormex was essential for obtaining an economical yield. The best results with regard to berry setting % , yield and cluster weight were obtained when the vines sprayed with Dormex on the second week of Jan., the first week of Jan., the third week of Jan. and the last week of Dec., in descending order.
Combined application of citric acid, magnesium, boron and iron was materially accompanied with improving berry setting %, yield and cluster weight rather than non- application.
Spraying the vines with Dormex at 2.0% on the second week of Jan. when the vines exposed to 110 C.H. along with application of citric acid at 0.025% , magnesium sulphate at 0.1% , boric acid at 0.0125 % and chelated Fe at 0.05% resulted in gaining an economical yield of Superior grapevines.
5-Harvesting date and quality of the grapes:
Application of Dormex at 1.0 to 4.0 % was very effective in advancing harvesting date and improving physical and chemical characters of the grapes in terms of increasing berry weight and dimensions (longitudinal and equatorial), total soluble solids %, total sugars % and total soluble solids / acid and decreasing berry index, shot berries % and total acidity % as compared to the check treatment. The promotion on harvesting date and quality of the grapes was associated with increasing Dormex concentrations. Increasing concentrations of Dormex from 2.0 to 4.0% had no material promotion, therefore it is enough to us Dormex at 2.0%.
Harvesting date and quality of grapes were obviously affected by varying dates of application of Dormex. Whereas spraying Dormex on the second week of Jan. when the vines exposed to 110 C.H. gave the best results regarding advancing harvesting date and improving quality of the grapes.
Treating the vines with citric acid, magnesium, boron and iron was favourable in advancing harvesting date and improving fruit quality compared to untreating the vines.
For advancing harvesting date and improving quality of the grapes, it is necessary to use Dormex at 2.0% on the second week of Jan. (when the vines exposed to 110 C.H.) plus citric acid, magnesium , boron and iron.
Conclusion:
From economical point of view, it is concluded to spray Dormex once on the second week of Jan. (when the vines exposed to 110 C.H.) at 2.0 % as well as spraying citric acid at 0.025 %, magnesium sulphate at 0.1% , boric acid at 0.0125% and chelated Fe at 0.05% four times at growth start , just after berry setting and at 14 days intervals for advancing harvesting date and improving yield and quality of Superior grapes. This recommendation was true under experimental and resembling conditions. Application of such promised treatment in one feddan contains 700 vines achieved expected net profit reached 5820 and 11250 Egyptian pounds over the check treatment during 2006/2007 and 2007/2008 seasons, respectively as previously mentioned in the Table (30) in the results.