Project Number :- QP1005130 (1/5/2011) Project Title :- Critical (temperature) thresholds and climate change impacts/adaptation in horticulture. Author(s) Name :- Peter Deuter et al. Research Provider :- Department of Employment Economic Development and Innovation (DEEDI), Queensland Project Number :- QP1005130 Project Leader :- Peter Deuter Senior Principal Horticulturist AgriScience Queensland Department of Employment Economic Development and Innovation Gatton Research Station Warrego Highway, Gatton Queensland 4343 Phone – (07) 5466 2222 Mobile – (0407) 636 907 Email – [email protected] Key Personnel :- Dr Neil White, Principal Research Scientist, Department of Employment Economic Development and Innovation, Toowoomba, Queensland. David Putland, Climate Change Officer, Growcom, Brisbane. Rachel Mackenzie, Chief Advocate, Growcom, Brisbane. Jane Muller, Senior Research and Policy Officer, Growcom, Brisbane. Purpose of the report :- Final Report documenting critical temperature thresholds for major horticultural commodities in Australia Funding sources :- Woolworths, Landcare, Horticulture Australia Limited, Queensland Government Collaborating institutions :- Date of the report :- 5th May 2011 Disclaimer: Any recommendations contained in this publication do not necessarily represent current HAL Limited policy. No person should act on the basis of the contents of this publication, whether as to matters of fact or opinion or other content, without first obtaining specific, independent professional advice in respect of the matters set out in this publication. Contents Page 1.0 Media Summary 2 2.0 Technical Summary 4 3.0 Introduction and Review of Literature 6 4.0 Overview of Critical Thresholds 13 5.0 Materials and Methods 14 6.0 Results 16 Case Studies - Lettuce 22 - Banana 39 - Apple 42 - Citrus 47 - Pineapple 52 - Tomato 54 - Macadamia 62 - Capsicum 64 - Avocado 68 7.0 Discussion 74 8.0 Technology Transfer 86 9.0 Recommendations - Scientific and Industry 87 10.0 Acknowledgments 90 11.0 Bibliography of Literature Cited 90 12.0 Appendix I - Literature Review 94 1 1.0 Media Summary Key Components of the Project A review of the literature and industry consultation was undertaken to document critical temperature thresholds for a number of major horticultural commodities. The focus was on temperature thresholds, to the exclusion of rainfall effects, because the majority of horticulture in Australia is irrigated. While this approach does not discount the importance of rainfall and associated runoff into irrigation storages, it is temperature which determines to a great extent the location and performance of the majority of horticultural commodities in Australia. Understanding the specific impact of temperature change on horticultural commodities is a necessary step in providing growers with the decision making tools to manage and adapt to climate change. Such information is critical to help preserve Australia’s profitable and productive horticulture industry. Industry Significance Horticulture in Australia comprises a large number of commodities contributing ~ $7 billion annually to the economy. Horticultural crops are grown in a wide range of production regions due to the diversity of micro-climates. Horticultural crops are particularly sensitive to temperature, most having specific temperature requirements for the development of optimum yield and quality. Key Outcomes & Benefits for Industry The key outcome of this project has been a better understanding of the temperature thresholds affecting a small number of horticultural crops, and the impact of further temperature rises on these commodities, under a changing climate. Conclusions In general, growers have managed past climate change quite well and are optimistic that they will continue to manage projected temperature increases into the medium term future. In many horticultural regions where the temperature threshold is currently exceeded at some specific times of the year, growers in the main have avoided production during these periods, as in general yield and quality are reduced when the temperature exceeds the threshold for each commodity. As temperatures continue to rise in all vegetable production regions through to 2030, growers are likely to respond by changing planting and harvest dates, and reducing the production season by a few weeks. If more adaptable vegetable cultivars are available to growers, the impact of reducing the length of the production season will be reduced, until such time as the genetic capability of more adaptable cultivars is exceeded. It is expected that it will not be until after 2030 that market access and the profitability of a reduced season in the majority of vegetable production districts will be a major factor in the increasing vulnerability of the vegetable industry. In districts where the threshold is not exceeded currently, and will be exceeded only on occasions, or not at all by 2030, growers may be able to take advantage of earlier planting in the spring, and later planting in the autumn, as temperatures continue to rise. For perennial fruit crops, the effects of exceeding thresholds is somewhat different to annual vegetable cropping. More adaptable varieties will be the long-term solution, where agronomic practices are not appropriate of not cost effective. Recommendations for future R&D Although the impacts of increasing temperatures on a range of horticultural crops are somewhat similar, there are sufficient differences between commodities, regions and seasons for additional assessment of critical temperature thresholds to be conducted for the very large number of horticultural commodities grown across a wide range of regions and seasons in Australia. 2 The next step should be an assessment of the vulnerability of major horticultural commodities and/or production regions in Australia. Those commodities and/or regions which are most vulnerable will require particular attention from growers and industry bodies. There is a need for additional assessment of other critical thresholds (e.g. rainfall) for the very large number of horticultural commodities grown across a wide range of regions and seasons in Australia. Recommendations for industry application More adaptable cultivars are required by all vegetable industries in Australia to cope better with a very variable as well as a changing climate. Identify those commodities and regions which will be most impacted by further rises in temperature (and decreases in rainfall runoff), and potential new or alternative locations where temperatures will be more favourable, up to and after 2030. Similarly, more adaptable fruit crop cultivars for some specific commodities such as apples will be required in the future as temperatures continue to rise. Identify those countries/regions, which currently export product to Australia, which will be significantly impacted by rising temperatures, and those which will become more competitive on the Australian market because of favourable impacts as a result of further changes to the world’s climate. Despite the lack of immediacy, growers and industry need to be vigilant in continuing to assess the changes in climate as they occur, and the impacts these changes will bring. The specific outcomes for each of the individual horticultural commodities assessed in this project should be directed to the Industry Bodies representing those industries. 3 2.0 Technical Summary Nature of the Problem Horticulture in Australia comprises a large number of commodities contributing ~ $7 billion annually to the economy. Horticultural crops are grown in a wide range of production regions due to the diversity of micro-climates. Horticultural crops are particularly sensitive to temperature, most having specific temperature requirements for the development of optimum yield and/or quality. In agriculture, a critical threshold is the point at which the production of a commodity becomes unviable due to identifiable change in a production variable. In horticulture, yield and or quality are usually the first to suffer as the threshold is approached or exceeded. Critical temperature thresholds differ for each commodity and often between different varieties. Science undertaken A review of literature and industry consultation was undertaken to document critical temperature thresholds for a number of major horticultural commodities. The focus was on temperature thresholds, to the exclusion of rainfall effects, because the majority of horticulture in Australia is irrigated. While this approach does not discount the importance of rainfall and associated runoff into irrigation storages, it is temperature which determines to a great extent the location and performance of the majority of horticultural commodities in Australia. The work program proceeded in the following stages: The current understanding of critical temperature thresholds was identified and documented through a review of literature for a selection of the major horticultural crops. Additional data on critical temperature thresholds was collected through consultation with informed growers, consultants and scientists. The impact of projected temperature change in 2030 was determined for selected horticultural commodities in current production regions using the information gained from the literature review. Potential adaption strategies documented. Findings reported through commodity specific case studies. Understanding the impact of temperature change on horticultural commodities is a necessary