The present research was aimed to evaluate the effects of the gibberellic acid, the biostimulant Crop-Set and girdling applied during bloom and post-bloom stage to improve yield and berry size of the grape cv. Thompson Seedless in the São Francisco River Valley, Northeast of Brazil. The trial was carried out throughout two growing seasons (2001 and 2002) in the Bebedouro Experimental Station, Embrapa Semi-Árido, Petrolina, PE. The trial was laid out in a randomized complete block design with three replicates, each replicate consisting of a four-tree plot. The treatments were: gibberellic acid aplied during five phases of development (10 + 15 + 15 + 50 + 50 mg.L-1 doses), Crop-Set in two doses 0,1 and 0,2% and trunk girdling, isolated or combined to each other. The combination treatments of girdling + gibberellic acid and girdling + gibberellic acid + Crop Set showed the best results, promoting the largest weight of bunches and size of berries with significative diferences compared to control. On the other hand, girdling caused damage in the tissue cicatrization and death of plants, so it is recomended caution to practice it. The yield was increased 63% in the combination girdling + gibberellic acid in the growing season of 2001, although it had not been observed significative diferences among treatments.
Vitis vinifera; gibberelic acid; citokinin; girdling; seedless grape
