Chilling-injury symptoms on the surface of eight cultivars or lines of tomato (Lycopersicon esculentum Mill.) fruit were mapped with respect to subtending locules. Mature-green (MG) fruit were chilled at SC for 10 to 25 days and then ripened to red ripe at 20C. Mature-green fruit showed a major portion of injury over subtending locules and on the stem end. The location of injury corresponded with the regions that were the last to ripen. The injuries of immature-green (IG) fruit treated in a similar manner were different from those of MG fruit both in appearance and in distribution.
Georges T. Dodds and Pamela M. Ludford
Georges T. Dodds, J. Wyatt Brown, and Pamela M. Ludford
Chilling of mature-green (MG) tomato fruit (Lycopersicon esculentum Mill. and related species) was investigated to determine the effect of chilling stress on surface color during low-temperature storage. Color measurements were made with a tristimulus calorimeter (L, a, b values), and data were analyzed by multivariate analysis of variance and canonical variates analysis. Changes in surface color of MG fruit during chilling were not correlated overall with relative chilling sensitivity of cultivars/lines; however, within standard and cherry types, chilling-tolerant fruit changed surface color more during chilling than chilling-sensitive fruit when fruit were picked early in the season. Early harvests were less chilling-sensitive than late harvests. The number of hours below 15.6C in the 200 hours before harvest was positively correlated with postharvest chilling sensitivity. A high vs. ambient relative humidity during storage did not affect chilling-induced percent change in color. Tobacco mosaic virus resistance led to less and Verticillium albo-strum Reinke & Berthier resistance led to more chilling-induced color change. There was no effect from resistances to Fusarium oxysporum Schlechtend f. sp. lycopersici (Sacc.) W.C. Snyder & H.N. Hans, alternaria stem canker (Alternaria solani Sorauer), anthracnose [Colletotrichun coccodes (Wallr.) S.J. Hughes], root-knot nematode (Meloidogyne hapla Chitwood), Phytophthora infestans (Mont.) deBary, or Stemphylium botryosum f. sp. lycopersici Rotem, Cohen, & Wahl. Our results show harvest date had an effect on chilling-induced changes in surface-color in MG fruit.
Stuart G. Reeves, Jacqueline F. Nock, Pamela M. Ludford, Lydia L. Hillman, Linda Wickham, and Richard A. Durst
The use of a new, inexpensive scanning reflectometer, the Colortron, as a field and laboratory colorimeter is investigated. The results obtained from a series of color swatches and from a variety of fruit samples are compared with those obtained from other commercially available, but more expensive, colorimeters (Hunter and Minolta). The Colortron is shown to be very good for gathering and analyzing data. The results of all three instruments were extremely close when measuring color swatches, but the Colortron gave aberrant results with certain fruit having translucent skin and flesh. Despite this caveat, it still has considerable potential for the measurement of fruit color in the field and laboratory.