الفهرس 
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Abstract
The current study in title “Effect of spraying seaweed extract and chitosan on growth and fruiting of Superior grapevines” was conducted during two successive seasons 2018 and 2019 on thirty own rooted, uniform in vigor and are sixteen years old ‘Superior Seedless’ grapevine grown in private vineyard farm located at Abwan Village, Matay district El-Minia Governorate where the soil texture is clay, well drained and water table depth not less than two meters. All selected vines are planted at 2 X 3 meters apart. Winter pruning was carried out at the first week of January and using cane pruning methods was followed. Vines load was Leaving 84 eyes per vine (on the basis of six fruiting canes X 12 eyes plus six renewal spurs X two eyes), using the assistance of gable supporting system. Surface irrigation system by using the Nile water was adopted.
The overall aim of this study is to improve understanding of the influence of spraying different concentrations of seaweed or/and chitosan at different concentrations on vegetative growth parameters, nutritional statues of vines, yield and berry physicochemical characteristics of ‘Superior Seedless’ grapevine, under El-Minia Governorate conditions. The experiment included nine treatments from seaweed extract and chitosan, individually or in combinations at different concentrations and control treatment were arranged as follows:
1- Control (untreated vines)
2- Spraying seaweed extract at 0.1%.
3- Spraying seaweed extract at 0.2%.
4- Spraying seaweed extract at 0.4%.
5- Spraying chitosan at 0.05%.
6- Spraying chitosan at 0.1%.
7- Spraying chitosan at 0.2%.
8- Spraying seaweed extract at 0.1% + chitosan at 0.05%.
9- Spraying seaweed extract at 0.2% + chitosan at 0.1%.
10- Spraying seaweed extract at 0.4% + chitosan at 0.2%.
The most important results obtained during both seasons could be summarized as follows:
1- Vegetative growth characteristics: All studied vegetative growth characters, i.e. main shoot length (cm), leaf area (cm2), number of leaves/shoot, wood ripening coefficient and cane thickness (cm) were gradually stimulated in response to spraying the ‘Superior Seedless’ grapevines with a seaweed extract (at 0.1% to 0.4%) and chitosan (at 0.05% to 0.2%) compared to untreated vines (control). The vines received the highest concentration of seaweed extract (0.4%) and chitosan (0.2%) in combination present the best results. However, non-significant differences were observed between the two higher concentrations of seaweed extract or/and chitosan, either single or combined application.
2- Leaf chemical contents: A promotion effect was observed on chlorophylls a & b and total chlorophyll as well as percentages of macro nutrient (N, P & K) and micro nutrient (Fe, Zn & Mn) in adult leaves when the vines received seaweed extract and chitosan either individually or in combination. Furthermore, spraying the vines with highest concentration of seaweed extract (0.4%) and chitosan (0.2%) produced the maximum values of chlorophylls and mineral nutrients during the two experimental seasons. However, non-significant differences were recorded between the vines received seaweed extract or/and chitosan at highest concentrations (at 0.2% & 0.4% for seaweed extract) and chitosan (at 0.1% & 0.2% for chitosan) individually or in combinations. On the other hand, untreated vines present the lowest chlorophyll contents and mineral nutrients. These data were true during both experimental seasons.
3- Yield and cluster physical properties.
Increasing the concentrations of seaweed extract (from 0.1% to 0.4%) and chitosan (from 0.05% to 0.2%) had no considerable promotion on the number of cluster per vines in the first experimental season of this study. However, the cluster weight and dimensions were improved significantly in the second experimental season. A remarkable promotion in cluster number/vine, cluster physical properties as well as yield (kg/vine) were observed. It is clear from the obtained data that improving yield and cluster physical properties were parallel to increasing seaweed extract or/and chitosan. However the best results were obtained from the vines received the highest concentrations from both materials (seaweed and chitosan) in combination. It is preferable to use the combination (seaweed at 0.2% + chitosan at 0.1%), whereas the differences between the two highest concentrations were non-significant, during both experimental seasons.
4-Percentage of shot berries: Remarkable and significant reduction was observed on such undesirable character due to using seaweed extract or/and chitosan at different concentration, this reduction was proportional to increasing the concentration used (seaweed from 0.1% to 0.4% and chitosan from 0.05% to 0.2%). However, non-significant differences were observed between the two highest concentrations neither for seaweed nor for chitosan, these findings were true during both experimental seasons. It is clear from the obtained data that, regardless the concentration used the combined application of seaweed and chitosan shows more effective in decreasing shot berries % rather than using each one alone. Other words, non-significant differences were observed between the two highest concentrations (0.2% & 0.4% for seaweed and 0.1% & 0.2% for chitosan), when spraying each one alone or using the two compound in combination. Then, from economical point view, for minimizing the percentage of shot berries in ‘Superior Seedless’ cluster it was preferable to spraying seaweed extract at 0.2% combined with chitosan at 0.1%.