Ammonium thiosulfate and 6-benzyladenine improve the crop load and fruit quality of ‘Delicious’ apples
S. A. Bound A B and S. J. Wilson AA Tasmanian Institute of Agricultural Research, University of Tasmania, 13 St Johns Avenue, New Town, Tas. 7008, Australia.
B Corresponding author. Email: sally.bound@dpiw.tas.gov.au
Australian Journal of Experimental Agriculture 47(5) 635-644 https://doi.org/10.1071/EA05217
Submitted: 18 August 2005 Accepted: 22 September 2006 Published: 13 April 2007
Abstract
Four trials were conducted over 3 years to assess the effect of ammonium thiosulfate (ATS) as a blossom thinner of ‘Delicious’ apple trees. In addition to determining the optimal concentration of ATS and the effectiveness of multiple applications, the effect on fruit quality was assessed. A program using ATS at bloom and 6-benzyladenine (BA) applied postbloom was examined. Multiple applications of ATS reduced crop load more than a single application. A concentration of 1.0% (v/v, 5800 mg/L) applied twice during the flowering period is recommended, with the first application at 20% bloom and the second at 80% bloom. Fruit firmness and sugar content were increased by ATS, and a positive relationship between fruit weight and sugar content and between fruit weight and firmness was demonstrated. ATS can also be effectively combined in a program with BA with the added benefits of increases in fruit size, firmness and sugar content; however, caution is advised to prevent over-thinning.
Additional keywords: desiccant, fruit set, postbloom thinner.
Acknowledgements
Thanks are due to Ferro Corporation (Australia) Pty Ltd, Chemicals Division for provision of the ATS and Abbott Australasia for provision of the CyLex. The technical support of Ms Caron Summers is also gratefully acknowledged.
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