Influência do ácido giberélico na melhoria dos cachos de uvas ‘BRS Tainá’ e ‘BRS Melodia’ no submédio do Vale do São Francisco

Abstract

The grapevine culture in recent years has stood out due to the diversification and offer of new cultivars. Each year, the fruit consumer market has been dictating criteria that crop breeders seek to meet. The production of seedless grapes is the biggest one. In the last decade, several cultivars of pyreneous table grapes were released, the most recent being 'BRS Melodia' and 'BRS Tainá', developed by Embrapa's 'Uvas do Brasil' Improvement Program, both recommended for cultivation in the sub-medium of the San Francisco Valley. However, these cultivars have a naturally small berry size, requiring the use of growth regulators to achieve the desired berry pattern in the market. The small size of the berry depreciates the appearance of the fruit and may negatively impact the prices achieved in the market, as the search for larger clusters and berries are more attractive to the consumer. This work aims to determine the ideal concentration of gibberellic acid associated with biostimulants to promote the increase in berry size and improve the characteristics of the bunches of grape cultivars BRS Melodia and BRS Tainá, in the Lower São Francisco Valley. In 'BRS Melodia', eight different doses (0, 12.5, 13, 17.5, 18, 22.5, 23, 27.5, and 28 ppm) of gibberellic acid were evaluated and in the last two production cycles also associated with Biostimulants, as a source of cytokinins. In 'BRS Tainá', four different doses (0, 20, 40, 60 and 80 mg.L-1) were evaluated, also with the association with biostimulants in a second experiment. The adopted experimental design was in randomized blocks with four replications and four plants per plot. The variables evaluated during the project were: production per plant (Kg), mass, length and width of the bunch (cm), stem mass (g), berry mass (g), length (mm) and berry diameter ( mm), berry firmness (N) soluble solids content (°Brix) and titratable acidity (mg.100 mL tartaric acid). The experiment was installed in two different private properties in the Petrolina-PE region, located in the Sub-Medium region of the São Francisco Valley, in the production cycles of the year 2021 and 2022. As a result, it was concluded that the biostimulant Maxcell associated with 30 mg.L-1 of GA3, fractionated into three applications (8+10+12) promoted an increase in most of the analyzed variables, mainly in the mass and size of the berry of the 'BRS Melodia' cultivar. For cv. 'BRS Tainá' better results were observed in the second cycle of experiment 01. The most responsive treatment was with the dose of 80mg.L-1 of GA3 alone. The association of gibberellin with biostimulants increased the mass of the stalk, impairing the appearance of the 'BRS Tainá' grapes, and therefore cannot be recommended.