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Jingwei Dai and Robert E. Paull

The Anthurium andraeanum `Kaumana' flower growth and development before and after emergence was studied. The process before emergence was long and slow. A tiny flower bud, about 0.3 cm long was formed 80 days before its emergence. The whole period before emergence was divided into three phases: cell division phase, slow growth phase and elongation phase. The characteristic of each phase was studied.

The leaf which bears the flower bud at its petiole base is called subtending leaf. Its growth had a significant influence on the flower bud growth at its petiole base. Detaching the young subtending leaf blade resulted in an earlier flower emergence.

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Jingwei Dai and Robert E. Paull

The postharvest life of Dendrobium spp. flower sprays was limited by wilting and shedding of individual “flowers. Late-summer-harvested sprays had a reduced postharvest life compared to winter-harvested sprays. Cultivars differed in postharvest life in response to packing and storing for 2 days at 22C. Water 10ss rates of `Princess' sprays continuously held in deionized water declined from ≈ 1.25 g/day per spray 4 days after harvest to 0.35 g/day per spray 20 days later. Flower shedding occurred when the rate of water loss fell below ≈1.0 g/day per spray. Addition of a floral preservative to the vase water slowed the decline in water loss and increased postharvest life. Sprays packed and stored for 6 days at 22C had half the postharvest life of nonpacked controls held in deionized water or of sprays packed for 2 or 4 days at 22C. Submerging sprays in water immediately after harvest did not significantly increase postharvest life; submerging the sprays after harvest, before packing, and again after unpacking reduced postharvest life. Sprays could not be held for more than 4 days at 10C without suffering chilling injury. Silver thiosulphate (2 mm) and other silver preparations had no effect on postharvest life, although silver ions did reach the top flowers of the spray; thus, ethylene may play only a minor role in spray postharvest life. The postharvest life of sprays was increased by using boiled deionized water in vase solutions and by the continuous presence of chloramphenicol. Other antimicrobial agents, such as Physan, sodium hypochlorite, and sodium dichloro-s-triazinetrione dihydrate were without effect. Microbial growth in the vase solution and at the cut stem end mav have reduced water transport and induced subsequent flower wilting and shedding.

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Jingwei Dai and Robert E. Paull

The growth and development of Anthurium andraeanum Andre cv. Kaumana flower before and after emergence from the subtending leaf base was studied. Eighty days before emergence, the anthurium flower was =0.3 cm long, enclosed by two tightly rolled stipules at the base of the subtending leaf petiole. During the rapid elongation stage of the leaf petiole, the flower (0.8 to 1.0 cm long) entered a period of slow growth 40 to 60 days before flower emergence. After the subtending leaf blade unfurled and had a positive photosynthetic rate, flower growth resumed. Spathe color development started =28 days before emergence when the flower was =50% of the emergence flower length (4.5 cm). At flower emergence, the spathe, excluding the lobes, was =75% red. The lobes did not develop full redness until 7 to 10 days after emergence. Peduncle growth was sigmoidal with the maximum growth rate 21 days after emergence. Spathe growth is characterized by a double sigmoid curve. The young, growing, subtending leaf blade had a negative net photosynthetic rate. Removal of this leaf blade advanced flower emergence by 18 days. The soft green leaf (25 to 30 days after leaf emergence) had a slightly positive measured net photosynthetic rate, and the removal of this leaf resulted in flower emergence 11 days earlier. A mature subtending leaf had the highest measured net photosynthetic rate, and its removal had little effect on flower emergence. The subtending leaf acted as a source of nutrients required for the developing flower. Altering the source-sink relationship by leaf removal accelerated flower emergence, probably by reducing the slow growth phase of the flower.

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Jingwei Dai and Robert E. Paull

The inflorescence of Protea neriifolia B. Br. was two-thirds of the total cut floral stem fresh weight and significantly influenced blackening of the attached 20 to 30 leaves. Floral stems harvested at five developmental stages were characterized for inflorescence diameter, fresh and dry weights, respiration, and nectar production. Inflorescence diameter and fresh and dry weights increased from stage 1 (very tight bud) to stage 5 (bracts reflexed). Respiration rate was high in stages 1 and 3. Nectar production began at stage 4 (open, cylindrical flower) and increased from 2.7 to 9.8 ml per flower with 15% to 23.5% total soluble solids as the flower opened. Postharvest inflorescence diameter, respiration rate, and nectar production increased and leaf blackening decreased when floral stems were placed in 5% (w/v) sucrose solution. Application of 14C-sucrose to a leaf subtending the inflorescence lead to >50% of the radioactivity being found in the nectar within 24 hours. These data indicate that leaf blackening in protea is the result of depletion of carbohydrate by the inflorescence, and that this depletion is primarily due to the sugar demand for nectar production.