الفهرس 
introductionOnly 14 pages are availabe for public view
 |  | from | 148 |  |  |
| | | from | 148 | | |
Abstract
This experiment was canied out over two successive seasons, 1993 and 1994 on 7 -years old, double cordon trained Flame seedless grapevines ~own in a private vineyard located at 65 kilometers from Cairo on Cairo Alexandria Desert Road. The vineyard was established on newly reclaimed sandy soil and the used inigation system was the drip inigation.
The investigation aimed to studying the effects of six concentrations of the commercial compound ”Donnex” (49% hydrogen cyanamide) namely; 0.0, 2, 3, 4,5 and 6% applied at different spraying dates (at 10, 9, ~ or 7 weeks before the expected nonnal date of bud break for the studied ~apevine cultivar under the conditions of the region where the experiment was achieved) on: some vegetative growth characters, some leaf and cane chemical constituents, bud behaviour, percentages of bursting and fruiting Duds, yield and fruit quality in tenns of berry physical properties and juice hemical constituents on the vines of the studied cultivar.
Twenty-four different treatments were included in this experiment, which was set in a completely randomized block design using the split-plot mangement with three replicates each consisted of three vines.
It was observed that the effects of the treatments on the studied characters reacted almost similarly in 1993 and 1994 seasons. In addition, no major differences could be detected between the effect of the applied eatment on any of these characters in first and second seasons.
The obtained results during the two experimental seasons could be lInunarized under the following topics.
l. Average Leaf Area:
The concentrations from 2 to 6% significantly increased the average leaf area compared to the water spraying control treatment (0.0% Donnex), however, the differences between the five concent rations was insignificant.
The second date of spraying was responsible for the highest average leaf area, while the last on resulted in the lowest values for this trait.
The interaction between the two studied factors was of significant effect on average leaf area, which was the highest when the vines were sprayed with 6% Donnex -at the second date of spraying (9 weeks before the Honnal expected date for bud burst).
2. Cane Thickness:
Cane thickness Significantly increased with increasing the concentration of Donnex to be maximized with the highest concentration (6%).
The earlier spraying was done, the highest was the cane thick ness. The highest values for the cane thickness were obtained from spraying Donnex at the first spraying date, while cane thickness took its lowest values when spraying was delayed to be done at 7 weeks before the nonmil expected date for bud burst.
This trait was significantly affected with the interaction between the two factors and cane thickness was the t,’Teatest when Flame
seedless grapevines were sprayed with the highest concentration of Domlex at the first date of spraying.
3. Weight of One-Yea I’-Old Pruning Wood:
The effect of the treatments on the weight of one-year-old pruning wood a trend similar to that of there effect on cane thick ness. The weight of pruning was the highest when the vines were sprayed with 6% Donnex at the first spraying (lO weeks before the nonnal expected date for bud burst).
4. Leaf Content of Nitrogen, Phosphorus and Potassium:
Nitrogen and potassium contents in leaf petiole were signifi cantly affected with Dormex concentrations as well as the date of spraying. The highest values for their percentages resulted from the highest concentration when sprayed at the first spraying ( 10 weeks before the nonnal expected date for bud burst). However, the treatment had no significant effect on leaf content of phosphorus.
5. Leaf Content of Chlorophyll A and B:
Leaf content of chlorophyll A and B was significantly higher with increasing the concentration of Donnex, as well as spraying was achieved earlier. The highest contents of the two chlorophylls were the highest when Domlex was applied at 6% ten 10 weeks before the nonnal expected date for bud burst.
Increasing the sprayed concentration of Donnex was associated with a progressive and announced increase in canes total carbo hydrates content. However, the differences between 4, 5 and G% concentrations was insignificant.
The percentage of total carbohydrates in the canes decreased with delaying Donnex spraying, however, the differences were not significantly approved in allY of the two experimental seasons. Also, the interaction between the studied factors was of insignificant effect on tllis trait.
The number of days from pruning to the start of bud burst (f:,’Teen point), number of days from pruning to the appearance of the first cluster and the days from starting bud burst to the appearance of the first cluster decreased with increasing the applied concentration of Donnex to be minimized when the concentration became 4%, there after, it was slightly increased. In other words, bud burst and appearance of the first cluster were advanced with increasing the used concentration of Donnex.
The first date of spraying (ten 10 weeks before the non11al expected date for bud burst).was responsible for the lowest number of days from prulllllg to the start of bud burst (green point), number of days from prunmg to the appearance of the first cluster and the days from staliing bud burst to the appearance of the first cluster.