Evaluation of Raspberry (Rubus sp.) Genotypes for Postharvest Quality and Resistance to Botrytis cinerea

Raspberries are a delicate, high value specialty crop with an extremely short shelf life. This is exacerbated by their susceptibility to postharvest decay caused by Botrytis cinerea Pers.:F. Of the three commercially available species, European red raspberry (Rubus idaeus L.) is the most widely grown. Yellow (R. idaeus L.), black (R. occidentalis L.) and purple raspberries (R. neglectus Peck. or R. occidentalis × idaeus hybrids) are mainly available at local markets and U-pick farms.  To the best of our knowledge, this is the first study to systematically examine postharvest quality differences between multiple raspberry types and the role of host genotype in decay resistance. The postharvest quality of 17 cultivars of red, yellow, purple and black raspberries was examined twice weekly from June to September over a two year period. Storage life of unsprayed, ripe berries was assessed weekly, while firmness, color, respiration, and ethylene evolution rates were measured in select harvests.  Our results show that black and purple raspberries took the longest to reach 25% rot in storage. Yellow raspberries took the shortest number of days to reach 25% rot. The incidence of bleed appeared to be unrelated to disease tolerance. Black raspberries had the lowest ethylene evolution rates, highest total anthocyanins and phenolics, and the lowest incidence of B. cinerea decay. Current studies are focused on confirming the relationship between B. cinerea resistance and postharvest physiology. This information could then be used to guide raspberry breeding programs to screen for improved quality and shelf life.