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- Author or Editor: Cynthia D. Fellman x
Abstract
N-phenyl-N′1,2,3-thiadiazol-5-ylurea (thidiazuron) and several substituted pyridyl phenylurea compounds have been demonstrated to stimulate in vitro meristem and shoot formation at unusually low concentrations. These compounds appear to have strong cytokinin-like effects on a wide range of species and on species that respond little to conventional cytokinins. Thidiazuron has been reported to stimulate shoot proliferation in several woody species (e.g., Acer and Malus). The addition of 0.5μm N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) to the culture medium caused dramatic shoot number increases in hardy dedicuous azaleas (Rhododendron sp.) cultured in vitro. In petunia (Petunia ×hybrida Hort. Vilm.-Andr.) leaf test systems both thidiazuron and CPPU caused greater proliferation when used as explant dips or in the medium than similar treatments with N-(phenylmethyl)-1H-purin-6-amine (BA). Further possible applications and roles for these compounds are discussed.
We evaluated the extent to which `Swenson Red' seeded grape (Vitis × spp.) responded to single and repeated GA3 applications to induce seedless fruit development. Field studies were conducted to test the time of pre-anthesis GA3 application (18, or 24 May or 3 June), the usefulness of postanthesis application, the optimum GA3 concentration (0, 0.075, 0.15, or 0.3 mm), and the method of application. The treatment dates that gave a high percentage of seedless berries with an acceptable berry count per cluster were 24 May with postanthesis application and 3 June pre-anthesis only. The optimum GA3 concentration was 0.15 mm applied both before and after anthesis. The most seedless berries developed when pre- and postanthesis applications were used, indicating many seedless fruit developed from flowers that would have abscised. There was no difference in percent heedlessness, number of berries per cluster, or number of seeds per berry between clusters dipped or sprayed with 0.3 mm GA3. Chemical uame used: gibberellic acid (GA3).
Abstract
Multiple shoots of Chinese chestnut (Castanea mollissima Blume), produced in vitro from axillary buds of juvenile shoots, were successfully rooted and transplanted to the greenhouse. Benzyladenine (BA) at 0.44 μM promoted the proliferation of axillary shoots, but 4.44 μM and 44.4 μM of BA inhibited buds from sprouting and promoted callus growth. Zeatin at 4.56 μM, induced longer and more vigorous shoots than BA, but did not promote the multiplication of axillary shoots. Rooting was achieved by a 1 sec basal dip of excised microshoots in 9.8 mM or 14.8 mM indolebutyric acid (IBA) solution. The treated shoots were transferred to a plant growth regulator-free medium in flasks or to plastic flats containing sand under high humidity. Roots developed within 30 days in both rooting regimes.