Effects of Sugar and Temperature on the Growth of Miniature Bulbs of Lilium japonicum Thunb. Cultured on a Rotary Shaker

Abstract

We investigated conditions which promote bulb enlargement of Lilium japonicum Thunb. cultured on a horizontal rotary shaker before transplanting in the soil.
Sucrose, maltose or glucose was added to the liquid Murashige Skoog's (MS) medium, and their utilization by the bulbs was monitored.. Sucrose was hydrolyzed into glucose and fructose, which resulted in an increase in osmotic pressure and subsequent sup-pression of bulb growth. Little maltose was absorbed by the bulbs, and therefore it was useless for bulb growth. A 3% glucose medium was optimum for bulb growth.
Bulb growth, as measured by fresh weight increase, in the shaking medium kept at 20°C was better than that kept at 25°C. However, cumulative absorption by the bulbs of NH₄⁺, NO₃^- and glucose from the medium at 25°C was almost equal to that at 20°C. It suggested that the consumption of sugar at 25°C was greater than that at 20°C.
More bulbs which were cultured in the MS medium with glucose, chilled at 0°C, potted, and planted in the greenhouse sprouted and bolted at 20°C than did those kept at 25°C. The chilling period for maximum sprouting and bolting was three months.