No abstract

During storage for 16 days at 0 or 4.5C or storage for 8 days at 20C, fresh raspberry (Rubus idaeus L. var. idaeus) fruit became darker, less red, and more blue as recorded in L* a* b* CIE coordinates. Cultivars maintained their relative at-harvest ratings throughout storage. Rates of change for cultivars during storage did not differ. Color changes depended on temperature, with rates of change fastest at 20C, especially during the first 4 days. Fruit stored 16 days at OC was more red and less blue than that stored at 4.5C. Maximum color change was reached after 8 days at 0 or 4.5C and after 4 days at 20C.

The field performance of micropropagated and runner-propagated subclones of `Olympus' strawberry (Fragaria × ananassa Duch.) was compared. The yield of micropropagated plants was not greater than that of runner-propagated plants. There was significant variability among micropropagated subclones, with the highest yielding subclone having 68% higher yield than the lowest yielding subclone in each of the first 2 years. However, after runner propagation for 4 years, selected subclones showed no differences in yield. Differences among subclones of `Olympus' were not stable and were most likely transient responses to the micropropagation environment. The apparent superiority of the subclones was not genetic.

The effects of delayed precooling on fresh red raspberry fruit during storage was determined. Precooling was delayed for 0.5 to 12 hours, followed by cold storage for 8 days, with subsequent storage at 20C for 24 hours. Weight loss was greater with increasing delays of precooling. Fruit that lost more weight during the delay period lost less during the subsequent S-day storage at 0C. The exception was fruit held for 12 hours before precooling. Weight loss during the final 24 hours at 20C showed no pattern. Cumulative weight loss at the end of the storage treatments was similar regardless of delay of precooling. Fruit strength was reduced by any delay of precooling. The effect of delayed precooling on color was not consistent in the 2 years using different cultivars. The results indicate that fruit should be precooled as quickly as possible after harvest for long-distance fresh marketing.

Fruits of red raspberry (Rubus idaeus L.) cultivars were harvested at the red-ripe stage and stored at 0C for up to 36 days. Firmness and titratable acidity generally decreased during storage, while anthocyanin and pH generally increased. Cultivars differed in rates and direction of change in firmness and pH during storage, and means differed at successive storage periods. Cultivars generally maintained their at-harvest ranking through storage in all characters. Cultivars differed in respiration rate. Respiration rate was positively correlated with ethylene evolution, rot, weight loss, and change in soluble solids concentration after 36 days in storage, and negatively correlated with change in firmness after all storage periods.