Harold F. Wilkins

Responses of Alstroemeria ‘Regina’ to temperature treatments prior to flower-inducing temperatures

Abstract Days to flower (DTF) were inversely related to the number of weeks (0–8) that Alstroemeria ‘Regina’ plants remained at 5°C, a vernalizing temperature, before being moved to 13°C, a vernalizing as well as a forcing temperature. However, when the number of weeks at 5°C was added to the DTF, no difference in the total time to flower was observed between plants treated at 5°C or those grown continuously at 13°C, as they both induced flowering. One-year-old plants maintained at 21°C, a non-inductive temperature, and not divided prior to the 5°C treatments, showed an increase in total shoot production, and delayed DTF, compared to plants which were divided. When divided plants were maintained for 16 weeks at 21°C prior to 5°C treatments, total shoot production was reduced but flowering was accelerated compared to plants maintained for 8 weeks at 21°C after dividing. Total shoot and flowering-shoot production was not affected by increasing the durations of time at 5°C when plants were grown at 21°C and divided prior to this treatment. Thus, the pre-treatment of dividing or maintaining plants at 21°C prior to a 5°C treatment affected subsequent shoot production and DTF.

The influence of sucrose, ethanol and calcium nitrate on the freezing-point and long-term low-temperature storage of carnation flowers

Abstract Both tight bud and open carnation (Dianthus caryophyllus L.) flowers survived −4°C for 5 days without injury if flowers were pulsed with 20% sucrose at 25°C for 24 hours prior to storage. Between the 8th and 10th day of storage, both stem and floral tissue froze. Flowers pulsed with 10 or 20% ethanol for 24 hours at 25°C survived −2°C for 5 days, while those pulsed in water failed to open normally or were frozen when stored at 0°C for 5 days. Flowers stressed (wilted) for 24 hours at 25°C survived for only 5 days at −4°C. After pulsing, tight buds were more resistant to freezing than open flowers and stem tissue was more resistant than petal tissue. However, during storage stem tissue froze before petal tissue. Using exotherm analysis, petal tissue froze at −2.3 or −4.7°C when first pulsed with water or sucrose and at −3.0 and −3.8°C after 7 days.

The influence of dimethylsulfoxide (DMSO) and sucrose on storage of carnation at −3°C

Abstract Open carnation ( Dianthus caryophyllus L.) flowers survived storage at −3°C for 20 days if previously pulsed with 6% dimethylsulfoxide (DMSO) and 20% sucrose. However, vase life after removal was only 1 day. With 15 days storage, such flowers were acceptable for 7.5 days. With DMSO alone, the possible freezing time was shorter than with sucrose alone. A 5% solution of DMSO increased longevity compared to the water control when flowers were not stored.