Floral Manipulation and Canopy Management in Longan and Rambutan. A report for the Rural Industries Research and Development Corporation by Yan Diczbalis and Dr. James Drinnan January 2007 RIRDC Publication No 07/031 RIRDC Project No DAQ-289A © 2007 Rural Industries Research and Development Corporation. All rights reserved. ISBN 1 74151 430 4 ISSN 1440-6845 Floral manipulation and canopy management in Longan and Rambutan Publication No. 07/031 Project No. DAQ-289A The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable industries. The information should not be relied upon for the purpose of a particular matter. Specialist and/or appropriate legal advice should be obtained before any action or decision is taken on the basis of any material in this document. The Commonwealth of Australia, Rural Industries Research and Development Corporation, the authors or contributors do not assume liability of any kind whatsoever resulting from any person's use or reliance upon the content of this document. This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186. Researcher Contact Details Mr Yan Diczbalis Dr James Drinnan Senior Research Scientist Research scientist Horticulture and Forestry Science Horticulture and Forestry Science Department of Primary Industries and Fisheries Department of Primary Industries and Fisheries Phone: 07 40641128 Phone: 07 40484647 Fax: 07 40642249 Fax: 07 40923593 Email: [email protected] Email: [email protected] In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 1, AMA House 42 Macquarie Street BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6272 4819 Fax: 02 6272 5877 Email: [email protected]. Website: http://www.rirdc.gov.au Published in January 2007 Printed on environmentally friendly paper by Canprint ii Foreword The longan (Dimocarpus longan) and rambutan (Nephelium lappaceum) are members of the Sapindaceae family. Both crops are native to Asia with longan considered to be subtropical in nature while rambutan tropical in nature. Both crops have been grown commercially in Australia for the last 20 years. Longan production occurs along the east coast of Australia with the majority of commercial longan plantings on the Atherton Tableland region (17oS) at an altitude of approximately 400 meters. Rambutan production is primarily confined to the wet tropical north Queensland coast (17ºS) and the wet/dry tropics in the vicinity of Darwin (12oS). Rambutan and longan experience irregular flowering, particularly when they are grown outside of their preferred environment. The north Queensland production region for these crops can be problematic due to a lack of consistent pre-flowering cold requirement for longan and pre-flowering dry weather requirement for rambutan. Excellent cropping can be achieved on both crops in some years, however poor flowering or nil flowering in “off” years make management and economic viability difficult for producers. To further exacerbate the irregular flowering issue, heavy pruning, every three to four years, for tree size control to assist tree management, and protective bird and bat netting control measures, reduce potential yields in the subsequent year. This project examined and reports on a range of pruning and flower regulation options to improve productivity. This project was funded from RIRDC Core Funds which are provided by the Australian Government This report, an addition to RIRDC’s diverse range of over 1500 research publications, forms part of our New Plant products R&D program, which aims to facilitate the development of new industries based on plants or plant products that have commercial potential for Australia. Most of our publications are available for viewing, downloading or purchasing online through our website: • downloads at www.rirdc.gov.au/fullreports/index.html • purchases at www.rirdc.gov.au/eshop Peter O’Brien Managing Director Rural Industries Research and Development Corporation iii Acknowledgments The authors acknowledge the assistance and cooperation of the Longan and Rambutan growers and their respective industry bodies; Australian Longan Growers Association (ALGA) and the Rambutan and Tropical Exotic Growers Association (RTEGA). We appreciate their time and patience in accommodating changes to normal management operations. We would also like to thank research station managers and staff and additional casual staff used for helping with the successful conduct of the trials. The assistance of the administration staff in presenting this final report and the other interim reports is gratefully acknowledged. iv Contents Foreword ................................................................................................................................................ iii Acknowledgments.................................................................................................................................. iv Executive Summary .............................................................................................................................. vii 1. Longan................................................................................................................................................. 1 2. General Materials and Methods .......................................................................................................... 3 3. Longan Literature Review................................................................................................................... 6 4. Methods and Rates of Potassium Chlorate Application...................................................................... 8 4.1 Introduction ................................................................................................................................... 8 4.2 Material and Methods.................................................................................................................... 8 4.3 Results and Discussions ................................................................................................................ 8 5. Effect of methods and rates of application of Potassium Chlorate on previously treated trees. ....... 11 5.1 Introduction ................................................................................................................................. 11 5.2 Materials and Methods ................................................................................................................ 11 5.3 Results and Discussion................................................................................................................ 11 6. Influence of flush age on the flowering response to Potassium Chlorate application....................... 14 6.1 Introduction ................................................................................................................................. 14 6.2 Materials and Methods ................................................................................................................ 14 6.3 Results and Discussion................................................................................................................ 16 7. Effect of Leaf Nitrogen on the flowering response to Potassium Chlorate....................................... 19 7.1 Introduction ................................................................................................................................. 19 7.2 Materials and Methods ................................................................................................................ 19 7.3 Results & Discussion................................................................................................................... 19 8. The use of heat-sums to predict harvest dates following potassium chlorate application................. 21 8.1 Introduction ................................................................................................................................. 21 8.2 Materials and Methods ................................................................................................................ 21 8.3 Results and Discussion................................................................................................................ 21 9. The effect of root pruning and the chemical growth retardant paclobutrazol applied post pruning on subsequent vegetative growth and flowering in longan. ....................................................................... 26 9.1 Introduction ................................................................................................................................. 26 9.2 Materials and Methods ................................................................................................................ 26 9.3 Results and Discussion................................................................................................................ 27 9.3 Summary ..................................................................................................................................... 28 10. Bearing Capacity or the relationship between fruit load and fruit size. .........................................