IMPROVING OUR UNDERSTANDING OF STORAGE STRESS USING CHLOROPHYLL FLUORESCENCE

R.K. Prange, J.M. DeLong , A.H. Wright
Since its introduction in 2001, chlorophyll fluorescence-based technology has proven capable of sensing several stresses that may affect fruit and vegetable quality in storage, e.g., O2, CO2, temperature, 1-MCP application and the presence of ammonia. Application of a stress results in an increase in the chlorophyll fluorescence parameter, Fα. The most popular application is the detection of the lower oxygen limit (LOL), which correlates with respiratory-based indicators of the LOL. Detecting the LOL and storing at or just above the LOL can result in a reduction in several apple and pear disorders in addition to increased quality retention. If CO2 was included in combination with O2 just above the LOL, the Fα baseline value gradually increased in some cultivars, e.g., ‘Golden Delicious’, suggesting a CO2-induced stress. If the CO2 was low, i.e., <2.0 kPa, there were no CO2-related disorders and an improvement was noted in firmness and titratable acid retention. Exposure to chilling temperatures was associated with an increase in the Fα baseline. And the addition of a low-intensity background light to prevent ‘dark adaptation’ enhanced the Fα increases associated with chilling stress. In 1-MCP-treated fruit, there was a transient increase in the Fα signal. The 1-MCP transient stress effect in the first 50 h was associated with transient CO2 and ethylene production increases. An accidental leak of ammonia refrigerant into a commercial store room of apples resulted in a stress-like increase in Fα. A group of carotenoid pigments (violaxanthin, antheraxanthin and zeaxanthin) can be enzymatically inter-converted through the xanthophyll cycle. Experimental results indicate the xanthophyll cycle operates as part of the plant cell’s response to low O2 stress, i.e., violaxanthin decreased, and zeaxanthin and the xanthophyll de-epoxidation state (DEPS) increased. These results suggest: 1) chlorophyll fluorescence is capable of detecting not only low-O2 stress but also other stresses; 2) storage using chlorophyll fluorescence technology allows for constant monitoring and control of O2, to achieve maximum quality benefits, including disorder control, without the use of postharvest chemicals; and 3) the xanthophyll cycle is involved in stress effects on chlorophyll fluorescence.
Prange, R.K., DeLong , J.M. and Wright, A.H. (2012). IMPROVING OUR UNDERSTANDING OF STORAGE STRESS USING CHLOROPHYLL FLUORESCENCE. Acta Hortic. 945, 89-96
DOI: 10.17660/ActaHortic.2012.945.10
https://doi.org/10.17660/ActaHortic.2012.945.10
chlorophyll fluorescence, lower oxygen limit, carbon dioxide, chilling, 1-MCP stress, ammonia detection
English
945_10
89-96

Acta Horticulturae