A Comparative Study for the Effect of Green Tea Extract and Some Antioxidants on Thompson Seedless Grapevines

Leaf area, plant pigments, leaf content of N, P, K, Mg, Ca, Zn, Fe and Mn, yield and berry quality of Thompson seedless grapevines in response to spraying green tea extract, ascorbic acid and citric acid each at 250 to 1000 ppm as well as salicylic acid at 50 to 200 ppm were investigated during 2012 and 2013 seasons.
Spraying green tea extract or any one of the three antioxidants was very effective in stimulating the leaf area, plant pigments, all nutrients in the leaves, yield as well as physical and chemical characteristics of the grapes in relative to the check treatment. The promotion was associated with using ascorbic acid, green tea extract, salicylic acid and citric acid, in descending order. In all cases, no clear effect was detected on all the investigated parameters among the higher two concentration of green tea extract and the three antioxidants.
Treating Thompson seedless grapevines three times with ascorbic acid at 500 ppm or green tea at the same concentration is suggested to be beneficial for promoting yield quantitively and qualitively.