Makio Hayashi

The In Vitro Environment and its Control in Micropropagation

The reasons for high production costs of micropropagated plantlets are analyzed. Problems requiring solutions by proper control of the in vitro environment for improving shoot/plantlet quality and cost effectiveness are revealed. Features of the in vitro environment and responses of shoots/plantlets cultured in vitro to the environment in conventional micropropagation are discussed in detail. The features and responses are interpreted from an environmental control point of view. Similarity of growth patterns between plantlets and seedlings under different in vitro environmental conditions is shown. Strategies for environmental control in micropropagation are discussed. The environmental effect on growth and development of shoots/plantlets cultured in vitro under controlled environments is shown. Advantages and disadvantages of heterotrophic, photomixotrophic and photoautotrophic micropropagation are discussed. Some novel environmental control systems are introduced.

Evapotranspiration Rate Measurement by Energy-balance Equation in a Single-span Greenhouse

An energy balance equation was used to estimate evapotranspiration in a greenhouse, and an instrument for this purpose was developed. It was found that the present method is simpler than that using the Penman-Monteith equation and the estimated values by this method were in good agreement with measured data. It is also reported that normal radiation sensor measurements on a horizontal surface are not adequate for measuring radiation received by a plant canopy in a greenhouse.

Effect of CO2 Enrichment on Rooting and Growth of Rose Cuttings

CO2施用が挿し木バラの発根・根部生育および新芽 (腋芽) 生育に及ぼす効果について, 発根剤処理の有無との関係で調べ, 以下の結果が得られた.(1) 発根剤処理は, 根部生育 (発根率, 発根数, 根部乾物重など) 促進の効果が認められた.他方, 腋芽生育 (乾物重, シュート長, 葉面積など) の抑制を引き起こした.(2) CO2施用は, 発根剤処理に比べると効果が小さいものの根部生育促進効果があり, さらに腋芽生育促進に対しても効果があること認められた.(3) 発根剤処理とCO2施用を組み合わせることで, 根部生育は最大となり, 発根剤処理による腋芽生育抑制は軽減された.以上より, CO2施用により挿し木苗生産期間の短縮が期待できる.