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  • Author or Editor: Mark S. Roh x
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The effect of long-term storage of lily bulbs at -2 °C (frozen storage) and of high forcing temperatures on plant height and floral abnormalities was investigated with Oriental hybrid lilies from 1998 to 2000. `Acapulco' and `Simplon' bulbs were stored frozen at -2 °C for various lengths of time and were forced in fan- and pad-cooled greenhouses with temperatures ranging from 11 to 31 °C, depending on the season. The same cultivars were also forced in greenhouses and maintained year-round under refrigerated air conditioning with day/night temperatures of 16/15.5 °C or 18.5/18 °C. Floral development immediately after storage and at different intervals thereafter was observed by scanning electron microscopy (SEM). The prolonged frozen storage reduced the number of flowers. High greenhouse forcing temperatures during summer significantly accelerated flowering, resulted in short plants, and increased the number of abnormal flowers. Forcing at a low temperature (15.5 °C) after planting the frozen stored bulbs resulted in longer cut stems than those forced at 25 °C for 30 days after potting. Bulbs can be stored up to 9 months and still produce high-quality Oriental hybrid lilies.

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The effect of long-term storage of lily bulbs at -2 °C and of high temperatures on plant height and floral abnormalities was investigated with Oriental hybrid lilies in 1997-2000. `Acapulco' and `Simplon' bulbs were stored frozen at -2 °C and forced in regular greenhouses with varying temperatures between 12 to 30 °C, depending on the season, and also air-conditioned greenhouses where temperatures were maintained year-round at 15.5 to 16 °C or 18 to 18.5 °C. Floral development was observed under a scanning electron microscope after -2 °C treatment. At flowering, stem length with dried and green leaves, number of leaves, and number of normal and abnormal flowers were counted. Although frozen-in storage duration affected plant height, flowering, and the number of abnormal flowers, high temperatures during summer significantly affected the speed of flowering, plant height, and the number of abnormal flowers. High temperature damage can be prevented by growing bulbs at low temperatures immediately after planting the frozen-in stored bulbs. Bulbs can be stored for 12 months to produce quality cut Oriental hybrid lily flowers.

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Flowering responses of two Anigozanthos hybrids were investigated. Flowering of 20-week old `Regal Claw' and A. manglesii x A. flavidus either from the main fan or the lateral fans was accelerated when plants received a night temp of 13 C, regardless of the photoperiod treatments. Temperature was the major factor controlling flowering of Anigo- zanthos hybrids. Flowering was accelerated from the lateral fans by treating plants at 15.5 or 18 C and a long day (LD) photoperiod. There were fewer than 2.5 branches in the stem at 18 C compared to more than 4.0 branches at 13 C. A night temp of 13 C was optimum for early flowering and for increased quality of cut flowers. At an inductive night temp of 13 C, Anigozanthos hybrids are day neutral while at 15.5 or 18 C they are quantitative LD plants.

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The main goal of this research was to develop Campanula glaumerata `Acaulis' plants transformed with the isopentenyl transferase (ipt) gene for increased growth of the axillary buds and en-hanced insect resistance. Isopentenyl transferase is a first enzyme in the cytokinin biosynthetic pathway. For Campanula transformation, leaf discs were co-cultivated with Agrobacterium tumefacience LBA4404, which harbored the binary vector pBC34 (A. Smigocki, Beltsville, Md.) that codes for the nos-nptII gene and the ipt gene controlled by the CaMV35S promoter. The transformation frequency was about three times higher when leaf blade explants were infected with LBA4404 containing pBC34 as compared to infection with pGUSINT, which contains the gusint gene instead of the ipt gene. This difference in transformation frequency was attributed to expression of cytokinin from the ipt gene. Transgenic plant lines containing the ipt gene were verified by southern hybridization and divided into three groups by phenotype following culture in vitro on MS medium: 1) yellow/large leaves, no rooting; 2) green/large leaves, no rooting; 3) green/normal leaf size, rooting. These different phenotypes could be due to different levels of cytokinin expression in the transgenic plants.

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Three lisianthus [Eustoma grandiflorum (Raf.) Shinn.] cultivars 0, 10, 17, 24, or 31 days from sowing were grown in 28C soil for 0, 7, 14, 21, or 28 days to determine the effects of high temperature during seedling growth on the development of rosetted plants. Increasing the duration of high-temperature exposure increased the percentage of rosetted plants for all cultivars. Such exposure for 28 days resulted in 96%, 93%, and 18% rosetted plants for cultivars Yodel White, Yodel Pink, and GCREC-Blue, respectively. Seedling age did not affect percentage of flowering `Yodel Pink' plants, but as seedling age increased to 31 days, the percentage of flowering plants increased with `GCREC-Blue' and decreased for `Yodel White'. In a second experiment, four lisianthus cultivars were grown at 22C for 3 weeks and then exposed for 28 days to soil at 22, 25, 28, or 31C. Increasing soil temperature resulted in more rosetted plants for all cultivars. With soil at 31C, 83%, 58%, 19%, and 2% of the seedlings rosetted for the cultivars USDA-Pink, Yodel White, Little Belle Blue, and GCREC-Blue, respectively.

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Corylopsis seed germination tests were conducted to assess the influence of harvest date (seed maturity) and cold stratification (CS) at 5 °C. Corylopsis gotoana seeds harvested on 12 July, 2 and 22 Aug., 6 and 20 Sept., and 1 and 10 Oct. 2011 were immersed in water for 20 min to separate fully developed seeds (full seeds) from empty seeds by floatation, and by X-ray scanning to identify full from empty seeds (Expt. 1). Immersing seeds in water did not effectively separate full seeds from empty seeds as evaluated by seed germination tests. Seeds harvested on or around 6 Sept. that sank showed translucent X-ray images with fully developed internal structures composed of embryo, cotyledons, and endosperm, and were considered mature. Without CS, >12% seeds harvested on 20 Sept. germinated, regardless of whether seeds were full or empty. Seeds of C. coreana harvested on 5 and 15 Sept., and 5 and 18 Oct. were stored dry at 20 °C until 27 Dec. and germinated after 0, 3, 6, 9, and 12 weeks of CS (Expt. 2). Longer than 6 weeks of CS was required to accelerate and increase the germination of seeds harvested on or after 5 Sept. Germination percentage of full seeds harvested on Oct. 18 was increased to >72% as the duration of CS treatment increased to 12 weeks. In conclusion, fully developed seeds harvested on or after 6 Sept. were considered mature and 6 weeks of CS accelerated germination and increased the germination percentage. Further, dormancy of Corylopsis seeds appears to be shallow since germination occurred without any CS.

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The effects of watering frequency, bulb size, temperature, and Promalin on flowering of Cyrtanthus elatus, were investigated. Bulbs must be 8 cm, in circum., with minimum of 10 leaf bases before the first inflorescence will develop from a swollen leaf base. One inflorescence was initiated for each set of 5 leaf bases. Watering frequencies did not affect flower bud development and abortion. Greater than 73% of plants developing from bulbs larger than 15.3 cm in circum. produced an inflorescence with 4 to 6 flowers when grown at 26/23C (D/N) and sprayed with 3,000 ppm Promalin. Anthesis was accelerated from 64 days to 39 days when temperatures were increased from 16/13 to 26/23C. A second inflorescence was also produced from some Promalin-treated plants grown at 26/23C. Flower bud abortion of inflorescences formed on the outer row of leaf bases appeared to contribute to irregular flowering.

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We investigated the interspecific relationships and intraspecific variations in the genus Corylopsis using RAPD and single nucleotide polymorphism (SNP) in the internal transcribed spacer1(ITS1), 5.8S ribosomal RNA gene specific in C. glabrescens Franch. & Sav. Differences in species identification between morphological characteristics and RAPD result were noticed in some accessions. All C. glabrescens, C. coreana Uyeki, and C. glabrescens f. gotoana (Makino) T. Yamanaka accessions clustered in one major group. However, they could be divided into five subgroups that are not related to the geographical origins. For example, C. coreana accessions from Korea were clustered with C. glabrescens from Japan. Although grouping based on SNP data does not agree with that by RAPD markers, it revealed the limitation in identification and classification of the genus due to high intraspecific variations in SNP. At SNP positions 464, 465, 466, 467, and 496, most accessions of C. glabrescens and C. coreana have C, G, A, A, and T, respectively. In both analyses, C. glabrescens, C. coreana, and C. glabrescens f. gotoana Japan are closely related and this suggests that nomenclature for these three species should be discussed. Although ITS1 5.8S ribosomal RNA gene can not be used for identification at a subspecies level of C. glabrescens, it proved to be useful to differentiate C. sinensisfrom C. sinensis var. calvescens. It is suggested to use C. glabrescens f. gotoana or C. glabrescens f. coreana rather than using C. coreana.

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