Genjiro Mori

Growth characteristics and yield of carrots grown in a soil ridge with a porous tube for soil aeration in a wet lowland

The growth characteristics and yield of carrots grown in a soil ridge with an aeration treatment were compared with those of carrots grown in a conventional ridge as a control under wet lowland field conditions. For the aeration treatment, a plastic porous tube was placed in the soil ridge. Water depth between the ridges in the aeration treatment and the control was kept at 20 mm throughout the growing period in order to imitate the wet soil conditions in tropical and subtropical lowlands. The fresh and dry weights of the storage root were 1.9 and 1.7 times greater, respectively, in the aeration treatment than in the control. The maximum root length in the aeration treatment was 1.8 times greater than in the control. The length of the leaf lamina and the leaf area per plant were greater in the aeration treatment than in the control. The fresh and dry weights of the total phytomass per plant were approximately 1.6 times greater in the aeration treatment than in the control. The fresh weight of the above-ground part was 1.3 times greater in the aeration treatment than in the control. The net photosynthetic rate and edible biomass index were greater in the aeration treatment than in the control. Carrot production in wet lowlands is possible if adequate aeration of the soil ridges is provided.

球根ベゴニアの葉片挿しにおける不定芽形成に及ぼす BA および葉片の置床方向の影響

We studied the effects of the type of leaf cuttings, 6-benzylaminopurine (BA) application, and the section position and orientation of leaf pieces on adventitious bud formation in leaf cuttings inserted in rockwool beds, using expanded young leaf blades of Begonia Tuberhybrida Group ‘Tenella’. In BA absence, 73% of whole leaf blades with petioles formed adventitious buds, whereas none of the 2 × 1.5 cm leaf pieces did at all. The percentages of surviving and adventitious bud formation of 2 × 1.5 cm leaf pieces without petioles were 47% and 0%, respectively. When these small leaf pieces were inserted in rockwool beds containing 0.25–2 ppm BA, the percentages of surviving and adventitious bud formation were 100% and 80%, respectively. In BA presence, the percentage of adventitious bud formation became lower from the base towards the tip of the leaf, and the leaf pieces at positions 2 cm away from the leaf bases did not form adventitious buds at all. When they were placed horizontally and vertically inverted, the percentages of adventitious bud formation were 60% and 80%, respectively.

Effects of temperature and moisture content of the substrate during storage on embryo development and germination in seeds of Musa velutina Wendl. & Drude

Summary Many wild plants in the Musa genus are diploid and form many seeds. However, their seeds rarely germinate after sowing. This non-germination phenomenon makes the breeding of Musa difficult. A method to promote seed germination for breeding and mass propagation has long been awaited. There are many reports on tissue culture or embryo culture, but the procedures are very cumbersome. In this study, we investigated embryo development during the seed germination process and examined optimal seed storage conditions. Germinability of the seeds of Musa velutina immediately after harvest and optimal seed storage conditions for embryo development and germination were investigated. Most seeds harvested in January and August did not germinate within 10 weeks after sowing at 10˚–30˚C. These seeds had immature mushroom-shaped embryos. When seeds with mushroom-shaped embryos were stored after harvest in vermiculite with different moisture contents, under various temperatures, a 75% (w/w) moisture content (–0.01 MPa) and 25˚C promoted embryo development and germination. Seeds stored for 2 months took 7 weeks to germinate, but seeds stored for 4–8 months germinated in 2–3 weeks.

Promotion of seed germination in Musa velutina Wendl. & Drude by scarification and GA3

Summary Seeds of Musa velutina Wendl. & Drude contain immature embryos and are unable to germinate under natural conditions. We investigated the effects of scarification and the application of exogenous gibberellic acid (GA3) on seed germination and on -amylase activity in these seeds. Scarification treatments that penetrated the hard seed coat promoted germination of seeds collected at harvest (76.7% germination by 14 d after sowing under aseptic conditions). On the other hand, intact seeds did not germinate under aseptic conditions. The application of GA3 to scarified seeds significantly promoted germination and decreased the number of days until germination. All seeds sown on filter paper moistened with 10 mg l–1 GA3 germinated within 14 d of sowing. GA3 increased the -amylase activity in scarified seeds, whereas application of the GA-biosynthesis inhibitor, paclobutrazol, decreased -amylase activity and resulted in a lower percentage of seed germination. These results indicate that the inability of M. velutina seeds to germinate resulted from the hard seed coat, which inhibited water absorption. Scarification and exogenous GA3 treatments promoted the germination of M. velutina seeds collected at harvest. Moreover, scarification treatment alone may increase the endogenous gibberellic acid content and induce the biosynthesis of -amylase in the embryo.

Seed germinability in Musa velutina Wendl. & Drude is markedly lowered by 1 week in dry-storage.

SUMMARY We investigated the effects of dry-storage of Musa velutina seeds on seed and embryo germination. Seeds were collected immediately after harvest and stored in dry vermiculite at 25°C, in the dark, for 0, 1, 2, or 4 months. The germinability of dry-stored seeds was assessed by incubation in vermiculite at 25°C for 4 months, with 75% [(w/w); –0.01 MPa] moisture content to promote embryo development in viable seeds. Seeds that had not been dry-stored and stored in vermiculite at 75% (w/w) moisture content for 4 months showed 90% germination by 20 d after sowing, but no seeds that had been dry-stored for longer than 1 month germinated. Seeds were also dry-stored at 25°C, in the dark, in Petri dishes for 0, 1, 2, 3, or 4 weeks after harvest and the embryos removed from these seeds were cultured on MS medium. All embryos that had been isolated from seeds at harvest (i.e., 0 weeks in dry-storage) germinated during embryo culture. However, embryos removed from seeds that had been dry-stored for 1 week showed a substantial decrease in both size and germinability. Seeds were also stored at different moisture contents for 4 months after harvest. No seeds that had been stored at 0% moisture content (i.e., dry) germinated, but > 85% of seeds stored at ≥ 25% (w/w) moisture contents germinated. Higher moisture contents increased the uniformity of seed germination, showing that M. velutina seeds rapidly lose their germinability through dehydration, indicating that they are sensitive to desiccation.

Effect of ascorbic acid onin vivoorganogenesis in tomato plants

Summary To promote shoot formation, ascorbic acid (AsA) was applied to the leaves of tomato stock plants treated using the complete decapitation method in which multiple shoots regenerate from the cut surfaces of the main and lateral stems. Treatment with AsA at 1, 10, 100, or 1,000 mg l–1 significantly increased the number of regenerated shoots ≥ 5 cm in length. AsA levels and the activities of anti-oxidant enzymes in plants treated with AsA were higher than those in control plants. H2O2 concentrations and malondialdehyde contents in plants treated with AsA were lower than those in control plants. Cells in the calli formed at the cut surfaces re-differentiated earlier in AsA-treated plants than in control plants. Our results indicate that foliar application of AsA promotes shoot formation at the cut surface of tomato stems.