Effects of Nitrogen Source, Phosphate and Sulfate in Liquid-Shaking Culture on the Growth of Miniature Bulbs of Linlium japanicum Thunb

Abstract

For liquid-shaking culture of bulbs of Liliurn japonicum Thunb., we analyzed the concentration changes in macro-inorganic ions in the culture media to clarify their relationships with bulb growth.
1. Inorganic ions, SO₄^2-, NH₄⁺, and especially H₂PO₄^- were consumed in large quantities by bulbs during culture, whereas the consumption of K⁺, Mg²⁺, and Ca²⁺ was very slow.
2. The optimum concentration of NH₄⁺ for bulb enlargement was 10-20 mM. The application of NO₃^- alone or NH₄⁺ higher than 30 mM as nitrogen source retarded the bulb growth. Root elongation was promoted by application of NO₃^- as the sole nitrogen source.
3. Root growth was poor in the medium containing a high ratio of NH₄⁺ /NO₃^-. Application of glutamine instead of NH₄⁺ promoted root growth.
4. The in vitro rooted bulbs sprouted and bolted abundantly after planting in the soil. Based on the above results, bulbs should be cultured first in a medium containing NH₄⁺ for bulb enlargement and then transferred to a NH₄⁺ free medium for root development. These treatments improved shoot growth after transplanting.
5. Although the absorption rate of H₂PO₄^- from the medium with the high concen-tration of NaH₂PO₄ was higher than that from the medium with the low concentration, bulb enlargement was not promoted.
6. High concentration of SO₄^2- in the medium inhibited bule growth.