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

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, SO42-, 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 SO42- in the medium inhibited bule growth.