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 Lilium japonicum Thunb., we ana lyzed the concentration changes in macro-inorganic ions in the culture media to clarify their relationships with bulb growth. 1. Inorganic i ons, SO42-, NH4+, and especially H2PO4- were consumed in large quantit ies by bulbs during culture, whereas the consumption of K+, Mg2+, and Ca2+ was very slow. 2. The optimum concentration of NH4+ for bulb enla rgement was 10-20 mM. The application of NO3- alone or NH4+ higher tha n 30 mM as nitrogen source retarded the bulb growth. Root elongation w as promoted by application of NO3- as the sole nitrogen source. 3. Roo t 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 H 2PO4- from the medium with the high concentration of NaH2PO4 was highe r than that from the medium with the low concentration, bulb enlargeme nt was not promoted. 6. High concentration of SO42- in the medium inhi bited bule growth.