テッポウユリりん茎の生育反応に関する研究 (第8報)

Abstract

This work was designed to investigate the effects of chilling of parent bulbs on the subsequent growth of inner bulb cores and also of scale bulblets that develop from the detached middle scale of Easter lily (Lilium longiflorum Thunb. ) cv. ‘Hinomoto’.After the parent bulbs, 14-15cm in circumference, were stored at 25 and/or 10°C for 35 days, the outer and the middle scales were detached from parent bulbs. Of these scales the outer scales were discarded, and the middle scales and the remaining bulb cores (inner bulbs) were planted at the depth of 3cm in wooden boxes and grown in the open field.The number of newly formed scale bulblets became larger as the chilling duration was increased. The chilling treatment increased the production of Epigeous Type Plants (ETPs) and decreased that of Hypogeous Type Plant (HTPs). In contrast with inner bulbs, leaf emergence from the scale bulblets was delayed as the chilling duration was increased.In the treatment of 4 to 5 week chilling, 90% of the inner bulbs almost simultaneously sprouted shoots, but the others remained dormant until the end of the experiment. All of the plants which sprouted shoots were tall in height and initiated the flower bud. In the treatment of 0 to 2 week chilling, however, inner bulbs produced very late but fairly concurrent shoot sprouting, and 100% of them completed the sprouting within 5 weeks. These plants were low in height and failed to initiate the flower bud. In the treatment of 3 week chilling, some of the inner bulbs developed shoots rather rapidly and the others slowly. Thus, the percent emergence of shoots in this treatment increased most slowly among the treatments. Plants with early shoot emergence were tall in height and initiated flower bud, whereas those with late shoot emergence were low in height and remained vegetative as in the treatment of 0 to 2 week chilling.From these results obtained it was concluded that effects of low temperature were essentially different in chilling duration and altered by the physiological condition of individual bulbs. Shorter chilling exerted almost no effects on the physiological condition of bulbs, whereas long chilling seemed to exert effects that were different in the maturity of bulbs. In other words, in more aged bulbs the chilling promoted shoot emergence and flower bud initiation, whereas in less aged bulbs it produced a dormant condition.The effects of chilling on the leaf and/or shoot emergence were different for the scale bulblet and the inner bulb. The leaf emergence from the scale bulblet was retarded but that of the inner bulbs was promoted as chilling duration was increased, though in the latter case its effects were confined to the more aged bulbs. This fact suggests that the leaf and/or shoot emergence of scales detached from a bulb is essentially different from that of scales which are left intact with the parent bulb.