Optimising crop management and postharvest handling for baby leaf salad vegetables Dr Gordon Rogers Applied Horticultural Research P/L Project Number: VG05068 VG05068 This report is published by Horticulture Australia Ltd to pass on information concerning horticultural research and development undertaken for the vegetable industry. The research contained in this report was funded by Horticulture Australia Ltd with the financial support of One Harvest. All expressions of opinion are not to be regarded as expressing the opinion of Horticulture Australia Ltd or any authority of the Australian Government. The Company and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests. ISBN 0 7341 1923 2 Published and distributed by: Horticulture Australia Ltd Level 7 179 Elizabeth Street Sydney NSW 2000 Telephone: (02) 8295 2300 Fax: (02) 8295 2399 E-Mail: [email protected] © Copyright 2008 HAL Project Number: VG05068 (Completed 22 Oct 2008, revised December 2008) Optimising crop management and postharvest handling for baby leaf salad vegetables Gordon Rogers et al Applied Horticultural Research Pty Ltd Horticulture Australia Project Number: VG05068 Project Leader Dr. Gordon S. Rogers Applied Horticultural Research Po Box 3114 BUNDEENA NSW 2230 Key Personnel Gordon Rogers – AHR Tom McAuliffe – OneHarvest Michael Titley – AHR James Le Budd – OneHarvest Brad Giggins – AHR Bartley Bauers – AHR Jenny Jobling – AHR Statement of Purpose: This project was a collaboration between OneHarvest, a commercial baby leaf manufacturer and Applied Horticultural Research. The research aimed to determine the optimum pre and post harvest management of baby leaf spinach, lettuce and rocket to ensure maximum shelf life and quality for the consumer. Funding This project is jointly funded by OneHarvest and Horticulture Australia Limited. Date: submitted October 2008; revised December 2008 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 ii Contents 1 Introduction ................................................................. 10 2 Materials and Methods ................................................ 20 2.1 Varieties ...................................................................................................... 20 2.2 Geographic regions of trials ..................................................................... 21 2.3 Optimum growing and storage requirements for baby leaf salads ..... 22 2.4 Seeding procedure .................................................................................... 25 2.5 Irrigation and crop protection .................................................................. 25 2.6 Sampling method for field trials ............................................................... 25 2.7 Sampling method for growth cabinet trials. ........................................... 26 2.8 Method for measuring leaf thickness ...................................................... 26 2.9 Method for measuring chlorophyll content ............................................ 26 2.10 Method for determining shelf life ............................................................. 27 3 Overview of the agronomic factors that affected postharvest shelf life of spinach ............................... 28 3.1 Introduction – Postharvest overview....................................................... 28 3.1.1 Postharvest overview - Materials and Methods .................................... 28 3.1.2 Postharvest overview - Results and Discussion ................................... 29 3.1.3 Postharvest overview - Conclusion ...................................................... 37 3.1.4 Postharvest Overview - References ..................................................... 38 3.2 Detailed study: Effect of growing temperature on the shelf life of baby leaf spinach under controlled conditions. .............................................. 40 3.2.1 Introduction ........................................................................................... 40 3.2.2 Materials and Methods ......................................................................... 40 3.2.3 Statistical analysis ................................................................................ 40 3.2.4 Results .................................................................................................. 41 3.2.5 Discussion ............................................................................................. 46 3.2.6 Conclusion ............................................................................................ 48 3.2.7 References ............................................................................................ 48 4 The effect of the time of the day of harvest on shelf life ................................................................................. 51 4.1 Introduction ................................................................................................ 51 4.2 Materials and Methods .............................................................................. 51 4.3 Results and Discussion ............................................................................ 52 4.4 References .................................................................................................. 55 5 The effect of variety and storage temperature on the Vitamin C content of baby leaf spinach .................... 56 5.1 Introduction ................................................................................................ 56 5.2 Materials and Methods .............................................................................. 56 5.3 Results and Discussion ............................................................................ 57 5.4 Conclusion ................................................................................................. 60 5.5 References .................................................................................................. 60 6 The effect of nitrogen on the shelf life of baby leaf lettuce (nutrition and irrigation experiments) .......... 62 6.1 Introduction ................................................................................................ 62 1 6.2 Materials and Methods (Overview) .......................................................... 62 6.3 Results ........................................................................................................ 65 6.4 Discussion .................................................................................................. 69 6.5 Conclusion ................................................................................................. 70 6.6 References .................................................................................................. 70 7 The effect of moisture absorbing sachets and vacuum cooling on the shelf life of baby leaf spinach and lettuce .................................................... 71 7.1 Introduction ................................................................................................ 71 7.2 The Effect of Moisture Reduction on the Quality of Baby Leaf Spinach and Lettuce ................................................................................................ 71 7.2.1 Materials and Methods ......................................................................... 71 7.2.2 Results and Discussion ........................................................................ 72 7.2.3 Conclusion ............................................................................................ 74 7.3 The effect of delayed vacuum cooling on the quality of baby leaf spinach compared to forced air cooling. ................................................ 74 7.3.1 Materials and Methods ......................................................................... 74 7.3.2 Results and Discussion ........................................................................ 76 7.3.3 Conclusions .......................................................................................... 77 8 Crop scheduling in baby leaf spinach ....................... 78 8.1 Introduction ................................................................................................ 78 8.2 Materials and Methods .............................................................................. 78 8.3 Results and Discussion ............................................................................ 79 8.3.1 Boisdale ................................................................................................ 79 8.3.2 Camden ................................................................................................ 85 8.3.3 Gympie .................................................................................................. 90 8.3.4 Stanthorpe ............................................................................................ 94 8.3.5 Commercial Data – Boisdale 2006-2007 .............................................. 96 8.4 Conclusions ............................................................................................. 111 9