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Nicholas P. Howard, Dennis Stimart, Natalia de Leon, Michael J. Havey, and William Martin

Impatiens (Impatiens walleriana) are currently among the most valuable and widely cultivated floriculture crops in the world. Attractive floral display is a primary goal for breeders of impatiens. Although breeders have selected for this trait, little consideration has been given to floral longevity as a means to increase the floral display of bedding crops. In this study, 259 commercial inbred lines of impatiens were grown in a greenhouse and evaluated for floral longevity as defined by the time between when a flower was completely open to when all of the petals abscised from the pedicle. Mean floral longevity of inbreds ranged from 3.3 ± 0.4 to 15.8 ± 2.5 days. Twelve inbreds (six with long floral longevity and six with short floral longevity) were chosen and crossed in a half diallel to create 66 hybrids that were analyzed for floral longevity in three greenhouse environments. Mean floral longevity of hybrids across greenhouse environments ranged from 2.8 ± 0.4 to 14.1 ± 2.8 days. Significant general (GCA) and specific (SCA) combining abilities for floral longevity were detected. GCA mean squares were 37 times larger than SCA mean squares, revealing that additive genetic effects play a more important role in the inheritance of floral longevity in impatiens. This information, coupled with the significant amount of variation for floral longevity among inbreds, indicates that there is good potential for breeding for floral longevity in impatiens to improve the floral display of hybrids.

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Yin Xu, Yizhou Ma, Nicholas P. Howard, Changbin Chen, Cindy B.S. Tong, Gail Celio, Jennifer R. DeEll, and Renae E. Moran

Soft scald is an apple (Malus ×domestica Borkh.) fruit disorder that appears in response to cold storage after about 2–8 weeks. It appears as a ribbon of dark tissue on the peel of the fruit, with occasional browning into the flesh. Several apple cultivars are susceptible to it, including Honeycrisp. The objectives of this study were to examine the cellular microstructure of fruit exhibiting soft scald and determine if any aspect of the peel microstructure at harvest could be indicative of future soft scald incidence. Light and electron microscopy were used to examine the peel microstructure of ‘Honeycrisp’ fruit that were unaffected or affected by soft scald. Tissue with soft scald had brown pigmented epidermal and hypodermal cells, whereas unaffected fruit peel epidermal cells were unpigmented. Cuticular wax of unaffected peel had upright wax platelets or clumps of wax, but peel surfaces with soft scald exhibited flattened granules and were more fragile than that of unaffected fruit. Epidermal cells of fruit with soft scald were more disorganized than that of unaffected fruit. Light microscopy was used to examine peels of ‘Honeycrisp’ fruit from four growing locations and fruit from a ‘Honeycrisp’ breeding population at harvest. ‘Honeycrisp’ and ‘Honeycrisp’ progeny fruit were also stored at 0 °C for 8 weeks and scored for soft scald incidence. Cross-sections of unaffected peel of stored ‘Honeycrisp’ fruit looked similar to that of freshly harvested fruit. No significant correlations were found between soft scald incidence and measured microstructural attributes of ‘Honeycrisp’ fruit at harvest, suggesting that peel microstructure cannot be used to predict possible soft scald incidence after storage.