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Takashi Hosoki

Effects of methyl disulfide (MeS2) on sprouting and phytohormones in dormant corms of spring-flowering gladiolus (Gladiolu×Tubergenii Hort. `Charm') were studied. Corms treated with MeS2 sprouted 30 days earlier than nontreated corms. The concentrations of endogenous promoters in the corm tissue increased and inhibitors decreased within 24 h of treatments. High concentration of inhibitors were present in the nontreated corms.

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Takashi Hosoki and Daisuke Kimura

Micropropagation of Centaurea macrocephala Pushk. ex Willd. was achieved by subculturing of vertically split shoots and division of axillary buds on MS-based medium with 0.44 μm BA. A proliferation rate of 2.0 per 16-day culture period was obtained. Seventy percent of microcuttings obtained through in vitro culture could be rooted on a modified Hyponex medium with 25 μM IBA. All plantlets were readily acclimatized and grown in a greenhouse. Chemical names used: benzylaminopurine (BA); indole-3-butyric acid (IBA).

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Morihiko Hamada, Takashi Hosoki and Toshiyuki Maeda

Potted plants of `Taiyoh' and `Hanakisoi' tree peony (Paeonia suffruticosa Andr.) were treated with a foliar spray of uniconazole or paclobutrazol for shoot length control. Uniconazole sprays at 25 or 50 ppm upon sprouting effectively reduced shoot length in both cultivars. The retarding effect was greater in `Taiyoh' than in `Hanakisoi' at 25 ppm. Uniconazole treatment did not influence flower diameter or days to flowering in either cultivar. Paclobutrazol sprays at 500 and 1000 ppm were less effective in reducing `Hanakisoi' shoot length than uniconazole sprays at 25 and 50 ppm. Chemical names used: E-1-(4-chlorophenyl)-4,4-dimethyl-2-(l,2,4-triazol-l-yl)-l-pentan-3-ol (uniconazole); (1RS, 3RS)-1-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-l-yl)-l-pentan-3-ol (paclobutrazol).

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Katsumi Ohta, Mika Suzuki, Shingo Matsumoto, Takashi Hosoki and Nobuo Kobayashi

We previously reported that growth of lisianthus [Eustoma grandiflorum (Raf.) Shinn.] seedlings is accelerated by amending the growing medium with 1% (w/w) chitosan. This finding prompted us to search for organic nitrogenous other substances like chitosan which could accelerate seedling growth. Seeds of E. grandiflorum `Peter blue line 2'were sown in a sandy loam growing medium containing 1% (w/w) chitosan, tryptone, casein, collagen or gelatin. At eleven weeks after sowing, leaf length and width, fresh and dry weights of the shoots and roots of twelve plants were determined for each treatment. Eleven weeks after sowing, the leaves at the fifth node had expanded in the chitosan, tryptone and collagen treatments while the leaves of the third node had not yet expanded in control plants. Fresh and dry weights of shoots and roots were significantly greater for plants grown in media amended with chitosan or tryptone. Percent nitrogen (N) and potassium (K) in the shoots and roots and percent phosphorus (P) in the shoots was greater only in the N side dressing treatment. The nitrate nitrogen (NO3-N) concentration was significantly greater in media amended with tryptone or collagen compared to the other treatments.