Fisher, Rosalind ORCID: 0000-0002-5609-6772, Thurston, Karen, Colgan, Richard ORCID: 0000-0002-0653-5845 and Rees, Deborah ORCID: 0000-0003-3541-0424 (2023) Monitoring low O2 stress in apples: what we can learn from chlorophyll fluorescence and respiratory characteristics. Postharvest Biology and Technology, 208:112661. ISSN 0925-5214 (Print), 1873-2356 (Online) (doi:https://doi.org/10.1016/j.postharvbio.2023.112661)

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Abstract

Dynamic controlled atmosphere (DCA) is becoming a storage method of choice for apple producers seeking to store long-term. There is limited prior work comparing DCA monitoring chlorophyll fluorescence yield (DCA-CF) and respiratory characteristics (DCA-RQ), particularly for the popular UK-grown apple cultivars ‘Gala’ and ‘Braeburn’. However, these techniques can give an insight into the physiological response of apples to low O2 storage, which could help to design more efficient and sustainable storage regimes. In this study the chlorophyll fluorescence (CF) and respiratory quotient (RQ) responses of ‘Gala’ and ‘Braeburn’ are compared in typical and exaggerated DCA conditions. Results show that not only do the two techniques differ in their detection of low O2 stress but the two cultivars studied also differ noticeably in their behaviour. CF increase was confirmed to be a reaction to a stress signal from inside the fruit. Respiration rate curves were found to reflect the internal structure of the fruit, with ‘Gala’’s more homogeneous tissues and greater gas permeability resulting in a strongly bimodal O2 consumption rate where the change in rate hypothetically corresponds with the majority of the fruit tissue switching to anaerobic respiration at the same time. CF and RQ showed noticeable differences between cultivars, agreeing with previous observations that ‘Braeburn’ is less tolerant of low O2 and elevated CO2 than ‘Gala’ (CF Lower O2 Limit (LOL) for Braeburn of approximately 0.75 kPa O2 relative to 0.5 kPa O2 for Gala). Additionally, the CF and RQ responses indicated different LOLs for ‘Gala’, at approximately 0.5 kPa O2 for CF and 0.25 kPa O2 for RQ. Elevated CO2 depressed both the CF and RQ response, with a strong depressive effect on the rate of CO2 evolution but little effect on the rate of O2 consumption.

Item Type:	Article
Uncontrolled Keywords:	apple storage; controlled atmosphere; chlorophyll; fluorescence
Subjects:	Q Science > Q Science (General) S Agriculture > S Agriculture (General)
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > Natural Resources Institute Faculty of Engineering & Science > Natural Resources Institute > Food & Markets Department Faculty of Engineering & Science > Natural Resources Institute > Postharvest Science and Technology Research Group
Last Modified:	05 Dec 2023 09:53
URI:	http://gala.gre.ac.uk/id/eprint/45047

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