This investigation was carried out during 2015 and 2016 seasons on cane trained Thompson seedless grapevines grown in a private vineyard located at El- Shudaa district, Minufiya Governorate. The vineyard soil texture is clay loam . The selected vines are planted at 2 × 3 meters apart. Pruning was conduced on the first week of Jan. in both seasons leaving 64 eyes per vine (4 fruiting canes × 14 eyes plus four replacement spurs × two eyes) .
This study was initiated for elucidating the effect of single or combined application of boric acid, magnesium sulphate and chelated –Zn on the bud behavior, main shoot length , leaf area , berry setting percentage , yield , mineral composition of leaf petiols as well as physical and chemical properties of Thompson Seedless grapes selecting the best treatment that responsible for producing filled clusters and higher productivity quantitively and qualitatively is considered another target.
The obtained results could be summarized as following :
1- Bud behavior: Single or combined application of boric acid, chelated –Zn and magnesium sulphate significantly controlled the percentages of bud brust and fruitful buds than non application.
2- Vegetative growth characteristics: The highest records of the growth parameters were observed in the two seasons from vines inoculated with combined with chelated-Zn 0.05%, Boric acid 0.05% and Mg sulphate 0.5%.
3- Fruit quality: The best results were obtained on the vines received four sprays of boric acid + chelated-Zn and magnesium sulphate together. Unsatisfactory results were recorded on untreated vines.
Therefore, it is necessary for obtain the best results spray the vines with boric acid at 0.05%, chelated-Zn at 0.05 and magnesium sulphate at 0.5% four times at the growth start, first bloom, just after berry setting and at one month later .