Effects of girdling and/or gibberellic acid on clusters and berries of seedless grape cultivar Maria (IAC 514-6) were analysed. The experiment was carried out in commercial vineyards located at Jundiaí, State of São Paulo, Brazil. The treatments were applied to the plants 14 days after bloom and consisted of: 1. girdle alone; 2. girdled plants with clusters dipped in a 200 mg/L gibberellic acid (GA3) solution; 3. clusters dipped in the same GA3 solution, in plants not girdled; 4. control plants: no girdle, no GA3. Parameters analysed were: cluster weight, length and width, number of berries, berry weight, length and width, total soluble solids and pH. Control plants presented by far the worst results. Girdle or GA3 improved extraordinarily cluster weight, length and width, and berry number, weight, length and width, when compared to the control. GA3 alone gave much better results than girdle alone for almost all the traits, although girdling was made in a lower position in plants not treated with GA3. Girdle alone led to a total soluble solids content superior to all other treatments. Girdle and GA3 showed a strong interaction affecting positively and significantly all the physical traits of clusters and berries.
grapevine; seedless grapes; cultural practices; girdle; gibberellic acid