Measurement of ethylene production as a method for determining the optimum harvest date of ‘Jonagored’ apples

The measurement of ethylene concentration in the apple core is considered a good method of determining OHD, but requires high accuracy and expensive equipment. The measurement of ethylene production seems to be a technologically easier method. During research conducted in the years 2003-2008, measurements of ethylene production were evaluated as a method for determining the harvest maturity of ‘Jonagored’ apples intended for storage. Measurements were carried out every 4-5 days starting a few weeks before the estimated harvest date. Apples were picked on four dates and after five months the loss of mass, firmness, TSS and TA was measured, the incidence of physiological disorders and fungal diseases was assessed and sensory tests were conducted to evaluate storability. Based on this evaluation it was determined which of those dates was OHD. After a period of low ethylene production, the production accelerated rapidly to reach an average level between 10.0 and 12.5 ppm kg-1 hr-1 on the OHD. Later, ethylene production rose still more sharply and quickly reached several dozens of ppm kg-1 hr-1. The accuracy of the new method was compared with other methods used to determine the maturity stage. The results obtained through the measurement of ethylene production showed the least deviation from the six-year average and only the results obtained using the Streif index method, which may be unreliable for some cultivars according to the literature, had a comparable margin of error.