Non destructive assessment of fruit maturity based on chlorophyll degradation has to consider pre-harvest treatments that can influence it

Harvest indices for apple fruit are usually based on destructive measurements such as starch pattern staining and firmness as well as measurements of internal ethylene concentration (IEC). Non-destructive assessment of fruit maturity to estimate harvest windows has long been a research goal for fruit production and postharvest storage.One recent tool that is under evaluation is the difference in absorbance (IDA), which estimates chlorophyll a content based on IDA at 670 and 720 nm. The IDA reading for most apple cultivars ranges from 0 to 2.5. Correlations between the IDA and other maturity indices can be detected. However, with the use of pre-harvest sprays such as 1-methylcyclopropene (1-MCP; Harvista) or aminovinylglycine (AVG; ReTain), inhibitors of ethylene perception and biosynthesis, respectively, IDA readings and other maturity factors can be dissociated. The IDA of ?Empire? fruit from the green side (IDA-green) is correlated with harvest date for all treatments combined (R2=0.43). However, the correlation with IEC is less pronounced in untreated and ReTain treated fruit than with Harvista treated fruit. This dissociation most likely originates through partial prevention of ethylene production, which delays autocatalytic production of ethylene and slows down processes such as starch hydrolysis, but does not influence chlorophyll degradation to the same magnitude. Therefore, IDA values have to be evaluated not only based on the cultivar and production region, but consideration should also be given to pre-harvest treatments which will influence chlorophyll degradation. SourcesNON-DESTRUCTIVE MATURITY ASSESSMENT OF APPLE FRUIT WITH USE OF DIFFERENCE IN ABSORBANCE (DA)Doerflinger, FC1, Nock, JF1, Watkins, CB1fcd26@cornell.edu1Cornell University, Ithaca, NY USAIHC 2014, International Horticulture Congress, 17-22 August 2014, Brisbane, http://www.ihc2014.org/Picture by scientificamerican.com