Increasing apple fruit set on 'Condessa' using growth regulators
2010
Leite, G.B. | Petri, J.L. | Couto, M. | Hawerroth, F.J.
Increasing the fruit set improves yield of apple cultivars that have a high rate of flowers drop when grown under adverse climatic conditions. Apple cultivars such as ‘Condessa’ have low chilling requirement and intense blooming. However, depending on the prevalent climatic conditions and year, the fruit set is too low to result in an economically viable yield. Under these conditions, the fruit set may be improved by applying growth regulators that interfere on plants metabolism and physiology. The effects of concentrations of Prohexadione calcium (PCa) or a mixture of PCa with Thidiazuron (TDZ) were studied in a field trial with ‘Condessa’ apple in a mild climate region in Santa Catarina State, Brazil. PCa or PCa+TDZ were applied at the phenological stages E2, F2, G, and H. PCa was applied at the concentrations of 0, 55, 110, 165, and 330 mg L-1, with and without adding 12 mg L-1 of TDZ. Independently of its concentration, PCa had little effect when applied single, while PCa+TDZ significantly increased fruit set and the number of fruit per tree. The phenological stage of application ware important than concentration of PCa. Compared to the control, PCa+TDZ applied at the stages G and H increased the number of fruit per tree by 267 and 391%, respectively.
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