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Deirdre Scott, Susan S. Han, and Thomas H. Boyle

Eight Easter cactus (Rhipsalidopsis Britt. & Rose) cultivars and five Holiday cactus (Schlumbergera Lem.) cultivars were used to study postanthesis floral development and individual flower longevity. Floral aging was characterized by desiccation of the perianth and ovary, and was generally followed by abscission of the entire flower from the phylloclade. Petal turgor was maximal during early development when petal color was most intense. Petal color became less intense in the later stages of development. Flower longevity ranged from 7 to 12 days and from 4 to 6 days for the Rhipsalidopsis and Schlumbergera, respectively. This study demonstrates that significant genetic variation occurs within Rhipsalidopsis and Schlumbergera for flower longevity.

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Royal D. Heins, Thomas F. Wallace Jr., and Susan S. Han

Chlorosis of Easter lily (Lilium longiflorum) lower leaves causes significant economic loss. Lily plants growing in 15-cm pots were sprayed 30, 60, or 90 days after emergence or at 60 and 90 days after emergence with 25 to 100 ppm each of benzyladenine and GA4+7 from Promalin (Abbott Chemical Co.) and were grown pot-to-pot until flower. Chlorotic leaf count at flower decreased as Promalin concentration increased; plants sprayed at 60 days had the smallest chlorotic leaf count. Chlorotic leaves at flower varied from 28% for control plants to 10% for plants sprayed with 100 ppm at 60 days and from 36% to 17% 3 weeks later, respectively. The Promalin sprays promoted significant stem elongation, but differences in height at flower were only 2 cm. Plants sprayed with 100 ppm at 30 days averaged one deformed flower per plant; plants sprayed at 60 days and 60 and 90 days averaged 0.0 and 0.1 deformed flower per plant, respectively. Additional trials in which only the lower part of the plant was sprayed prevented any chlorotic leaves without any significant effect on final height or flower bud quality.

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Deidre Scott, Susan S. Han, and Thomas H. Boyle

The display life of individual flowers was determined for 8 cultivars of Easter cactus (Rhipsalidopsis hybrids) and 5 cultivars of Holiday cactus (Schlumbergera hybrids). For Easter cactus and Holiday cactus cultivars. the display life of individual flowers ranged from 7 to 12 days and from 4 to 6 days, respectively. In a second study, flowering plants were exposed to 0, 0.4, or 1.0 μl·liter-1 ethylene (C2 H4) for 48 h and were evaluated at 0 and 5 days after C2 H4 treatments. Plant responses to C2 H4 were dependent on C2 H4 concentration, cultivar, and stage of floral development: Easter cactus cultivars were less sensitive to C2 H4 than Holiday cactus cultivars. There was no correlation between display life of individual flowers and sensitivity to C2 H4. These studies demonstrate that: 1) there is substantial genetic variation within and between genera for postharvest performance; and 2) display life of individual flowers and plant sensitivity to C2 H4 should be evaluated when selecting for postharvest performance.

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Thomas H. Boyle, Renate Karle, and Susan S. Han

The reproductive biology of Schlumbergera truncata (Haworth) Moran and S. xbuckleyi (T. Moore) Tjaden was examined in a series of experiments. At anthesis, pollen grains are spherical, 54 to 62 μm in diameter, and tricellular. The receptive surface of the stigma is densely covered with elongated papillae and is devoid of exudate during the period of flower opening. When compatible pollen was applied to mature stigmas, germination occurred between 20 and 30 minutes after pollination and pollen tubes penetrated the stigma surface between 30 and 40 minutes after pollination. Pollen tubes exhibited a nonlinear pattern of growth in the upper two-thirds of the style, and the maximum rate of growth (≫1.9 mm·h-1) occurred between 12 and 18 hours after pollination. Full seed set was attained between 32 and 48 hours after pollination. Genotypic variation in the time required to achieve full seed set was partly attributable to differences in stylar length. Seeds were fully mature 6 months after pollination, but delaying fruit harvest until 8 months after pollination did not affect seed germination.

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Susan S. Han, Abraham H. Halevy, Roy M. Sachs, and Michael S. Reid

Exposure of dormant corms of Triteleia laxa `Queen Fabiola' to 20 ppm C2H4 for 7 days promoted flowering of small corms and resulted in increased apical meristem size, early sprouting, early flowering, more flowers per Inflorescence, and increased fresh weight of daughter corms and cormels. The respiration rate of the C&treated corms increased to four to five times that of the controls during the 7-day treatment, declined markedly after termination of the C2H4 treatment, but remained higher than that of the controls. The C2H4 effects were associated with increased growth rate and consequently a greater final size of the apical meristem (determined by scanning electron microscopy). Leaves produced by C2H4-treated corms were wider, longer, and weighed more than those of the controls.

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Susan S. Han, Abraham H. Halevy, Roy M. Sachs, and Michael S. Reid

Flowering of brodiaea (Triteleia laxa syn. Brodiaea laxa `Queen Fabiola') did not have an obligate requirement for manipulation of temperature or photoperiod. Vernalization of corms reduced the greenhouse forcing phase but did not alter the number of flowers per inflorescence or scape length. Long photoperiods hastened flowering but decreased flower quality and flowering percentage. Scape length, which was not affected by photoperiod or mother corm size, was increased when plants were grown at night temperatures < 10C. Diameter of the apical meristem in the dormant corm, flowering percentage, and flower quality were not affected by a 10-fold increase in corm size above a critical weight (0.6 g). In contrast, the weight and number of daughter corms were closely correlated with mother corm size. The optimum planting depth for brodiaea corms was 10 cm below the soil surface.