저온과 GA3에 의한 태백 작약의 휴면과 개화 조절

Abstract

These studies were conducted to investigate chilling requirement for breaking dormancy and to determine the optimum transferring date and GA3 treatment for breaking dormancy and flowering of Paeonia lactiflora Taebaek. Dormant rootstocks of P. lactiflora Taebaek were placed into three chilling regimes (0, 5, or 10°C) for different durations (0, 3, 6, 9, or 12 weeks) to determine the minimum chilling requirement for dormancy release. Plants that were subjected to each chilling treatment were maintained in a controlled glasshouse. All control plants, which did not receive chilling temperature, failed to sprout under forcing condition until the end of the experiments. The number of days to bud bursting and flowering gradually decreased as the duration of the chilling treatment increased. Lower temperatures caused more rapid bud sprouting. Percent sprouting and the number of shoots and flowers consistently increased as plants were exposed to colder chilling temperatures or longer chilling durations. All plants sprouted and flowered when treated at 0°C for 6 weeks (1,008 h CU) or longer. At least for 9 and 12 weeks were required to induce sprouting and flowering when the plants were treated under 5 and 10°C, respectively. Six week treatment at 0°C (1,008 h CU) can be recommended to break dormancy effectively for forcing culture of P. lactiflora Taebaek. To identify natural cumulative chill unit according to transferring date and effects of GA3 application time for manipulating dormancy breaking and flowering, dormant rootstocks of P. lactiflora Taebaek were exposed to natural cumulative chilling and applied by GA3 according to transferring date. Shoot emergence and flowering did not occur throughout the experiment when dormant rootstocks were transferred to a glasshouse from September 10 to October 29, in which natural cumulative chill unit (NCC) was only 0 h. Days to sprouting and flowering from transferring date were shortened as transferring date was delayed. All plants flowered normally with shoot growth when transferred after December 31 (1,222 h NCC). All dormant buds that were applied with GA3 sprouted regardless of transferring date, but failed to flower due to shoot blasting and flower bud abortion when transferred from September 10 (0 h NCC) to November 12 (185 h NCC). Shoot blasting was 38% when transferred on November 26 (429 h NCC). When plants were applied with GA3 after at least December 17 (876 h NCC), they flowered without blasting. Plant height and stem diameter were not affected by GA3 treatment. Days to sprouting and flowering decreased by GA3 treatment, and the number of flowers increased irrespective of insufficient chilling accumulation compared to 1,222 h NCC on December 31. At least 1,222 h NCC could be recommended as practical forcing methods for dormancy release, subsequent growth, and normal flowering of dormant P. lactiflora Taebaek in temperate climate region. GA3 treatment played an important role in breaking dormancy of P. lactiflora Taebaek when they received insufficient chilling. These results demonstrated that at least 1,222 h NCC and 1,008 h CU at 0°C might be required for dormancy release and normal growth and flowering of P. lactiflora Taebaek. Furthermore, GA3 treatment for forcing culture of P. lactiflora Taebaek could accelerate percent sprouting, days to sprouting, and promoted flowering.