Effects of Ethylene Scrubber and Light on Yellowing of Geranium Transplants

Abstract

The yellowing of geranium transplants under simulated non-refrigerated transit conditions was investigated with ± KMnO4-based ethylene scrubber or supplemental light. The transplants were stored in the dark at 20 °C in glass jars or cartons, some of which were treated with ± ethylene scrubber (8 g) and/or ± light. Transplants (8) were removed daily for measurement of leaf yellowing intensity (= percentage of the sum of the products of yellowing rate and leaf number within the rate over the potential maximal sum, where rate 0 equals no yellowing; 1, discrete margin yellowing; 3, yellowing along margin; 4, uniform yellowing). Yellowing was evident after 1 day storage (3 days postharvest). The yellowing of `Pinto Red' geranium transplants stored in cartons progressed similarly ± ethylene scrubber (≈99% yellowing intensity on day 5). In jars, the scrubber delayed the yellowing of `Pinto Red' from 83% to 75% by the end of the 5-day test period. In a separate test of `Pinto Salmon' in jars, yellowing was delayed from 68% without scrubber to 30% with scrubber. Weak incandescent light plus scrubber substantially reduced yellowing in `Pinto Pink'(43%) compared with dark, – scrubber (96%) after 6 day storage. Under fluorescent light, yellowing in `Pinto Pink' was ≈20%. The results showed that the absence of light was the key stress factor causing yellowing in geranium transplants. Yellowing retardation by ethylene scrubber was observed only in a closed system and the effect was variety dependent.