الفهرس 
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Abstract
The trial was executed during 2022 and 2023 seasons on 30 ”Earl sweet” Seedless grapevines, seven-year-old vines grafted onto Paulsen rootstock grown in a private vineyard located at the West of Matay Center, Minia Governorate, Egypt.
The vines were pruned during Winter in the two seasons at the first week of Jan. Vine load was 72 eyes/vines. Different treatments resulted in different lengths of fruiting spurs. The gable supporting system was utilized, and all of the chosen vines got standard vineyard horticulture treatments.
The following ten treatments application from different concentration of seaweed extract with different time were included in this study:
1. Control (sprayed with tap water).
2. Seaweed extract at 0.05% (sprayed once).
3. Seaweed extract at 0.05% (sprayed twice).
4. Seaweed extract at 0.05% (sprayed thrice).
5. Seaweed extract at 0.1% (sprayed once).
6. Seaweed extract at 0.1% (sprayed twice).
7. Seaweed extract at 0.1% (sprayed thrice).
8. Seaweed extract at 0.2% (sprayed once).
9. Seaweed extract at 0.2% (sprayed twice).
10. Seaweed extract at 0.2% (sprayed thrice).
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Each treatment was replicated three times, with randomized complete block statistical design. Sprayed shoots of seedlings with seaweed extract once (at the beginning of growth), twice (at the beginning of growth and after berry setting), while the thrice (at the beginning of growth, after berry setting and one month later).
The following parameters were measured to evaluate the effects of different concentration seaweed extract spraying on growth (main shoot length cm, number of leaves/plant, Leaf area cm2, cane thickness mm, and pruning wood weight/vine kg), Leaves chemical content (chlorophyll content, N, P, K%, Zn, Fe and Mn ppm), yield (berry setting %, number of cluster/vine, average cluster weight g, length cm and width cm, yield/vine kg), and physical quality of berry (shoot berry%, average berry weight g, berry length, and diameter cm) as well as chemical quality of berry (TSS%, total acidity, TSS/acidity ratio, and total sugar%).
The obtained results could be summarized as follows:
1. Vegetative growth parameters:
Vegetative growth parameters expressed as main shoot length, number of leaves/plant, leaf area, cane thickness and pruning wood weight/vine as affected by foliar application various concentration of seaweed extract at different times during the winter seasons of 2022 and 2023. All concentration of seaweed extracts significantly increased the mean values of mentioned parameters in comparing to the control treatment. The mean values of traits increased with increasing number of sprayings, the best treatment in this respect was foliar application with seaweed extract at 0.2% thrice. Additionally, the results showed that the 2nd season was substantially greater than the 1st with the same trend.
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2. Leaves chemical content:
Results express the average values of leaves chemical characters (chlorophyll a, b, total chlorophyll, total carotenoid, N, P, K%, Zn, Fe and Mn ppm) of “Early Sweet” grapevines as affected by foliar application various concentration of seaweed extract at different times during the winter seasons of 2022 and 2023.Foliar application with various concentration of seaweed extracts significantly increased the mean values of studied parameters than those obtained from the untreated plants. In addition, with increasing number of foliar applications during growth stages increased the content of pigments and nutrients comparing to the control. In this respect, the highest mean values of traits recorded with folia application of seaweed extract at 0.2% thrice.
3. Yield and cluster characteristic:
The effect of foliar application with seaweed extract at different concentrations and frequenciesduring different time on “Early Sweet” grapevines yield expressed in berry setting%, number of cluster/vine, average cluster weight, yield/vine, average cluster length and width in comparing with the control treatment. It is evident that the highest values of yield parameters was associated with vines sprayed with 0.2%. The increase in concentrations of seaweed extracts significantly increased mentioned parameters during both seasons except number of cluster/vine in the 1st seasons. In addition, the increase in sprayed time during growth stages also increased the traits and the best time with vines spayed three time at the beginning of growth, after berry setting and one month later during both seasons.
4. Berry physical characteristic
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Morph-physical parameters of grapevine “Earl Sweet” as shoot berry%, average berry weight, length and diameter are a crucial factor for good marketing either locally, regionally or globally as affected by foliar application with seaweed extract in different times during growth stages at different concentrations 0.05, 0.1 and 0.2% in comparing to the control treatments during seasons of 2022 and 2023.Vines sprayed with seaweed extract at different times during growth caused a significant increase all physical parameters except shoot berry% was decreased, which mean that the highest concentration 0.2% at the beginning of growth, after berry setting and one month later (three times) was the best for recording the best values of physical berry traits during 2022 and 2023 seasons.
5. Berry chemical quality characteristics
Results express the average values of chemical quality characters (TSS%, total acidity, TSS/acidity ratio and total sugar) of grapevine cv. ’Earl Sweet’ as affected by foliar application with seaweed extract and number of foliar times during seasons of 2022 and 2023. All concentration of seaweed extract were significantly increased TSS, TSS/acidity and total sugar of grapevine berries, while total acidity was decreased comparing to the untreated plants. In addition, the best values of berry chemical qualityrecorded with plants sprayed with 0.2% seaweed extract three times at the beginning of growth, after berry setting and one month later during both seasons.