Effects of illumination on absorption of glucose, inorganic ions and glutamine from a liquid-shaking culture medium and subsequent enlargement of small lily bulbs (Lilium japonicum thunb.)

The enlargement and nutrient absorption from a liquid-shaking culture with or without glucose by Lilium japonicum bulbs were investigated. Promotion of NH4+, NO3- and H2PO4- absorption by illumination occurred after one or two weeks in the medium, independent of glucose. Glucose absorption from the medium was promoted by illumination three or four weeks after treatments were started; a concomitant promotion of bulb enlargement was noted. These results indicate that nitrogen uptake was accelerated by illumination as well as bulb enlargement through the increase in glucose absorption. The effects of glutamine supplement on the bulb enlargement and nitrogen uptake were investigated because it is absorbed more readily than inorganic nitrogen ions are. Bulb enlargement and absorption of total N were promoted by the presence of glutamine in the medium even in the dark. Thus,adding glutamine to the medium could substitute for illumination in promoting bulb enlargement; it would eliminate the need for light and, thereby, reduce the cost of bulb production by liquid-shaking culture.