Impact of dormex concentration and spraying date on the fruitful flame seedless grapevines Amira S.A. Abd El-Rahman.

الملخص EN

This study was conducted on fruitful flame seedless grape vines grown in Esna district, Luxor Governorate, Egypt to study the effect of five Dormex (hydrogen cyanamide) concentrations i.

e.

, (0.5, 1.0, 2.0 and 4.0% ) and four spraying dates (last Dec.

week, 1^st, 2^nd, and 3^rd jan.

week), as well as the interaction effect of their 20.0 possible combinations during both 2017/2018 and 2018/2019 seasons.

So, the complete randomized blocks design with four replications was employed to conduct such factorial experimental.

The obtained data revealed that, most evaluated parameters responded specifically to two investigated factors (Dormex conc.

and spraying date).

However, the trend and rate of variances differed not only from one measurement to another, but also differences due to Dormex concentration were more pronounced than spraying date.

Anyhow, some parameters like as: 1- bud burst % , 2- shoot length, 3- leaf area, 4- cane thickness, 5- pruning wood weight, 6- fruit set % , 7&8- yield either as number or weight of clusters/vine, 9- cluster weight, 10- 100 berries weight, 11- berry dimensions (length and diameter), 12- TSS% and 13- total sugars % were in positive relationships to Dormex concentration from one hand and the 3^rd spraying date (2^nd week of January) was the most suitable.

From this study, data show clear significant with the aforesaid parameters except those of can thickness, pruning wood weight, fruit set % and (weight and dimensions) of berry, where variance was relatively moderate or too few to reach level of significance.

On the contrary, the trend of response took the other way around either with the shoot berries % or leaf N, P and K% particularly as the specific effect of Dormex concentration was the concerned whereas the control (water sprayed vines) exceeded different Dormex spray treatments.

In addition, other leaf nutrient contents i.

e.

, Ca, Mg and Fe did not significantly influence.

As for the interaction effect the specific effect of each investigated factor was directly reflected on their combinations, so the 4.0% Dormex concentration which sprayed through the 2^nd week of January was the superior for most parameters and it could be recommended to be applied for flame seedless vineyards under the same environmental condition of such experimental region as an advisable rest breakage agent.