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- Author or Editor: Thomas J. Sheehan x
Rhizome cultures of American lotus [Nelumbo lutea (Willd.) Pers.] were established in vitro from excised embryos cultured in liquid half-strength Murashige and Skoog medium. Effects of medium supplementation with either BA, zeatin, GA3, or ABA on growth and development were evaluated. Neither BA nor zeatin had a significant effect on rhizome growth and development. Maximum rhizome growth and node number occurred in medium supplemented with 290 µm GA3 (100 mg·liter–1). Rhizome growth was inhibited in the presence of 0.38 µm ABA (1.0 mg·liter–1) and greater. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA), 2-methyl-4-(1H-purin-6-ylamino)-2-buten-1-ol (zeatin), (1α, 2β, 4aα, 4bβ, 10β)-2,4a, 7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1, 10-dicarboxylic acid 1,4a-lactone (GA3), [S-(Z,E)]-[5-(1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2,4-pentadienoic acid (ABA).
The effect of postharvest dips on the longevity of Anthurium andraenum cultivar Nitta and Alpinia purpurata was evaluated. The inflorescences were dipped in a 200 ppm benzyladenine (BA) solution, an antitranspirant, or water for 10 minutes. After dipping, anthuriums were placed directly in water and gingers were placed in either water or a 2% sucrose solution and placed in interior conditions (10 μmol m-2s-1 for 12 hr/day, 21±2C). Ginger longevity was increased by 10 days or more by the sucrose solution. The greatest longevity of gingers was obtained when dipped in either BA or the antitranspirant and held in the sucrose solution. Anthurium longevity increased 10 days when dipped in BA, while the other treatments had little effect.
Procedures for in vitro establishment, rapid shoot proliferation, and ex vitro plantlet acclimatization of Cryptocoryne lucens de Witt were determined. Shoot cultures were established from surface-sterilized shoot tips cultured on Linsmaier and Skoog salts and vitamins medium (LS) solidified with 0.8% (w/v) agar and supplemented with 2.0 μm BA and 0.5 μm NAA. The effect of BA (0 to 20 μm) and 0.5 μm NAA on shoot multiplication from single-node and clustered triple-node shoot explants was determined after 35 days. The most efficient shoot proliferation (7.7 shoots/explant) occurred from single-node shoot explants cultured on LS + 20 μm BA and 0.5 μm NAA. Maximum plantlet establishment was achieved by direct sticking of triple-node (cluster) microcuttings in either soilless planting medium or polyurethane foam cubes. Production of highly branched salable plants from microcuttings was possible within 18 weeks. Chemical names used: N-(phenylmethyl) -1H-purin-6-amine (BA); 1-naphthaleneacetic acid (NAA).
Plant tissue culture instructors face a dilemma when selecting laboratory exercises for large classes. Class size and equipment limitations may require that the exercises be performed without a laminar flow hood. The problem is further complicated when one attempts to choose an exercise to demonstrate adventitious shoot formation. There are few plant species from which suitable tissue explants can be obtained to demonstrate rapid adventitious shoot formation. Problems associated with surface sterilization, extended culture duration, or sporadic shoot regeneration limit the usefulness of most explants for classroom demonstrations.
A broad source of Gerbera × hybrida Hort. germplasm was evaluated for vase life. Senescence mode, i.e., bending or folding of stems or wilting of ligulae was also recorded for flowers evaluated. Intensive selection was practiced to improve vase life. About 10% of the plants from a sample population were selected for having flowers with high vase life. Progeny means for vase life resulting from a topcross between these plants and `Appleblossom' were used to select five plants (about 1.5% of the sample population) whose flowers had high vase life. A diallel cross using these five plants as parents resulted in a progeny population with an increase in mean vase life of 3.4 days compared to mean vase life for the initial sample population. Increases in vase life means for days to bending, folding, and wilting were 0.3, 3.5, and 1.2 days, respectively. Plants with flowers which senesced due to wilting had the longest mean vase life before and after breeding. Changes in proportion of senescence modes were observed; bending decreased, folding and wilting increased. Frequencies of bending, folding, and wilting were compared to vase life means for 10 progenies. Proportion of bending generally decreased as vase life increased.
Intensive selection to improve vase life was performed on a sample population of Gerber ×hybrida Hort. from a broad source of germplasm. Progeny of a 5 × 5 diallel cross yielded estimates of narrow sense heritability (h2 = 0.28) and broad sense heritability (H2 = 0.28) for vase life based on a mean of 1.96 measurements per plant. Additive gene action is postulated to control this character since the difference between total genotypic variance and additive genetic variance components was small. Repeatability (r = 0.57) based on a single measurement per plant was moderately high. Heritability estimates were also determined based on 1, 2, 3, 5, and ∞ measurements per plant. Heritability ranged from 22% to 39%.