Analysis of petal extracts from various species revealed a wide range of lipoxygenase (LOX) activity among sources. A large increase in LOX activity was observed during senescence in both gladiolus (Gladiolus × hortulanus Bailey) and carnation (Dianthus caryophyllus L.) petal tissue. The increase began before the first visible signs of senescence were evident and activity peaked at early to mid-senescence stages. LOX activity of petal extracts from gladiolus was inhibited in vitro by phenidone, a known LOX inhibitor.

Plants of the foliarly variegated cultivar Saintpaulia ionantha Tommie Lou and the florally variegated cultivar Candy Lou were regenerated through tissue culture from leaf sections, petal sections, and subepidermal tissue. This provided explants with derivatives of all histogen layers of the shoot apex, layers I and II only, and layers II and III only. Over 1,000 plants of Tommie Lou and Candy Lou were grown to flowering. A low level ofphenotypic variation was observed, but in no case could this be attributed to the separation of genotypically distinct cell lines. The foliar variegation pattern of both cultivars was stable through in vitro propagation. In contrast, the chimeral components of the flower color pattern in Candy Lou separated during regeneration. These data demonstrate that Tommie Lou-type foliar variegation is not caused by periclinal chimerism and that all leaf cell layers possess the genetic information necessary to produce variegated foliage. The production of all green and all white plants from a radiation-induced periclinal chimera demonstrated that the system used could detect chimeral separation. These results support the contention that adventitious shoots in Saintpaulia almost always differentiate in vitro from a derivative(s) of a single histogen layer, and this layer is usually the LI.

Plants of the foliarly variegated cultivar Saintpaulia ionantha Tommie Lou and the florally variegated cultivar Candy Lou were regenerated through tissue culture from leaf sections, petal sections, and subepidermal tissue. This provided explants with derivatives of all histogen layers of the shoot apex, layers I and II only, and layers II and III only. Over 1,000 plants of Tommie Lou and Candy Lou were grown to flowering. A low level of phenotypic variation was observed, but in no case could this be attributed to the separation of genotypically distinct cell lines. The foliar variegation pattern of both cultivars was stable through in vitro propagation. In contrast, the chimeral components of the flower color pattern in Candy Lou separated during regeneration. These data demonstrate that Tommie Lou-type foliar variegation is not caused by periclinal chimerism and that all leaf cell layers possess the genetic information necessary to produce variegated foliage. The production of all green and all white plants from a radiation-induced periclinal chimera demonstrated that the system used could detect chimeral separation. These results support the contention that adventitious shoots in Saintpaulia almost always differentiate in vitro from a derivative(s) of a single histogen layer, and this layer is usually the LI.

The poststorage and post-shipping quality of Lilium longiflorum Thunb. ‘Nellie White’ plants sprayed with silver thiosulfate (STS) complex or phenidone was observed in a simulated interior environment. Bud abortion and foliar chlorosis increased while floral longevity declined with increasing storage period from 0 to 4 weeks in the dark at 2°C. One to 3 days of simulated, boxed shipment at 23° subsequent to 3 weeks storage at 2° further increased foliar chlorosis but did not influence bud abortion or floral longevity. Whole plant STS sprays (0.5 to 2.0 mM Ag) prior to harvest reduced storage-induced bud abortion and increased floral longevity, but did not reduce foliar chlorosis. Ethephon application to plants that had been stored for 3 weeks at 2° induced bud abortion and abnormal floral development. STS application (1.0 mM Ag) prior to storage reduced ethephon-induced disorders. Preharvest whole plant sprays of phenidone decreased bud abortion on stored and nonstored plants but did not influence floral longevity. Uptake of phenidone and STS through cut petioles enhanced ethylene production during opening of excised lily buds. Ethylene production increased while respiration declined during senescence of excised buds. STS did not reduce but did delay the peak of ethylene production during senescence of lily flowers. Chemical names used: 1-phenyl-3-pyrazolidone (phenidone); (2-chlorethyl)phosphonic acid (ethephon).

A survey of seven known lipoxygenase (LOX) inhibitors showed that 0.1 mm DHN in a vase solution extended ‘Royalty’ rose vaselife by 2.5 days. Phenidone (PHE) did not enhance rose vaselife. Subsequent experiments showed no effect or a decrease in vaselife from both PHE and DHN application on roses, gladioli, and carnations. Sugar source and pH of the solution did not influence the effectiveness of the inhibitors on carnations. Carnations previously held without water for 24 hr showed only a minor increase in vaselife (2.6 days) from application of a vase solution containing 0.1 mm PHE. The commercial usefulness of LOX inhibitors in floral preservatives is therefore questionable. Chemical names used: 1-phenyl-3-pyrazolidone (phenidone); 1,5-dihydroxy-naphthalene (DHN).